Update December 2022 -- Before reading this chapter, see the website below on how you can save a lot of money by making used solar panels essentially brand new again at the cost of pennies:
https://www.youtube.com/watch?v=a_cTA3abWWEHaving owned a small solar system for nine years as of 2017, I have a few things to say with a tribulation outlook. Whether to go solar in the trib is a tough decision, but an even harder one is whether to go solar before the trib. On the good side, you can start to pay for the solar system now by the money saved on the grid. And it's far better to enter the trib a little experienced on how to use the system best. The risk in buying early is obvious, since you don't know for sure when the Time will arrive. Some people like to have a sense of security for future emergencies, not minding large expenditures in return for peace of mind, but if you would feel sore to have made large purchases for tribulation purposes, if the trib did not arrive in your lifetime, then you should be slower to make the leap.
Having a solar system isn't complete security, anyway, as the equipment can break down. I purchased Outback equipment, and have seen two computer boards fry (both in the inverter), the first one in less than two years, totally unexpected because the inverter can handle a lot more power than I usually demand of it. It stinks, but having extra boards seems like a good insurance policy. Or, ask which board is most likely to go. For me it was the same board twice, the one with the large tubes, whatever it's called.
Outback uses its mother boards over and over. When they send me a "new one," they demand the old one back, and claim to refurbish it, but, obviously, there are resistors / capacitors and other items in the unit that are aged, and these units go out that way to other people, with certain break-down predicted at any time thereafter. Outback tells me that so long as the mother boards are in working condition when they receive them back, they go out that way. Shame. They give a five-year warranty on mother boards in a newly-bought inverter, but only 90 days in a refurbished unit. What's that tell you? This is an underhanded way for Outback to supply itself with extra money, but for us, it's a high risk. If you trust Outback, you can buy a new board as an extra. In 2016, the boards I needed were about $500 new, and half that refurbished. I'm not sure I believe Outback when they say that every new inverter comes with brand-new boards.
I was "fortunate" when the electric company wanted about $12,000 to install power to my new property. It turned out that there was no choice but to go solar at a cost of about $9,000 U.S. that included eight 130-watt solar panels and eight 530-amp batteries, which is considered a small solar system...but it's borderline-enough for me alone, though it's a curse to be sure. I installed the system myself, but if you can't, it's yet another expense. If you're handy, you can use the manuals to install most of the system, then call an electrician in to make sure you've done it all correctly.
The threat of less-expensive, thin-film panels has pushed the cost of silicon panels way down. The webpage below tells (and shows in a chart) that, after testing, thin film out-performed, in the efficiency category (though the definition of "efficiency" is not well explained) the common / conventional types of panels. This contradicts what others are saying (perhaps rumors originating from silicon providers). The bottom line on efficiency is how much money it costs (to purchase and install the system) per watt of power absorbed from the sun. Silicon panels last 20 years or more, but we won't need them for that long. Should we buy used panels?
Panels don't deteriorate much due to sunshine when not in use. One page: "On average, solar panels degrade at a rate of 1% each year. That's backed up by the solar panel manufacturer's warranty, which guarantees 90% production in the first ten years and 80% by year 25 or 30."
Inexpensive thin-film panels should prove to be advantageous for tribulation survival. The film doesn't last as many years, nor capture as much energy per area, but for trib purposes, who cares? We should look into thin film absolutely.
Batteries are still fairly expensive (mine were about $250US each in 2008). The good news is, we shouldn't need many batteries, and they last more than four years, so long as they are not abused. The battery charger (or charge controller) was $400, and the 3500-watt inverter $1,600. After these expenditures, at current prices, you'll be off to races...as the turtle.
I have eight batteries but do with only four when it's not continually cloudy for weeks in a row. It's not a bad idea to have eight on hand, but to use four only, alternate between packs from time to time so that both get a work-out. If you ruin one pack from neglect, you'll have some power from the other. All eight of my batteries are in pretty good shape after nine years, mainly because I have used little power from them. The main threat: if you demand too much power from batteries when they are low in charge, it can reduce the performance of the batteries permanently or simply age them faster. The solution: don't use electrical power when the batteries have drained to roughly half-full of charge, unless the sun shines enough to handle what watts you are using at the time.
Four panels and four batteries can handle typical power tools for a not-bad length of running time on sunny days, but roughly only 30 minutes for a cloudy day if the battery pack starts off full in the morning. It's not likely going to be full in the morning. So, you will need to wait for sun. That's life as a solar turtle.
Four panels and four batteries can do a lot. Running a washing machine, no problem. Want music? No problem. The computer, no problem. The four panels will do it in most times of the year in most places without worry, and I've learned that I can even run a small (5.5 cubic foot) freezer and a small fridge together, in non-winter months of a northern latitude, using just four batteries and eight panels.
Your main tribulation concern might be the water pump. It takes very little power for your household needs if it's pumping horizontally, say from your rain barrels or nearby stream to a pressure tank in the house. Most of the power needed is due to the pressure tank; my current 1/2 HP pump (bought refurbished) runs something like a minute to get the last gallon into the tank, such a waste of power. It takes four minutes roughly to fill a small water tank that a new pump fills in less than a minute. Don't risk a used pump, in other words, because this item is important in an off-grid survival situation.
The new 1/2 HP pump probably runs on about 700 watts. One minute of operation is 700 / 60min = about 12 "watt-hours" (you better get used to that phrase), and one hour of operation would be 700 watt-hours (like running seven 100-watt bulbs for an hour). For most in-house situations, the pump will not run an hour daily. If it's a problem to power the pump, use pee bottles by night, or outdoor pee holes (you can all have your very own, bonus). It's doable. Pumping water into an open tank in the attic takes far less power than pumping into a pressure tank.
Pumping vertical is another matter. It's hard work for a submerged pump. Four batteries can't handle the pump running very long continuously. For spread-out showers, laundry and toilets, it's usually no problem, but for watering the vegetable garden, forget it.
A full and healthy 24-volt battery pack with no sun shining on the panels sits at 25.2 volts. When the sun shines, the voltage rises to about 29 volts. So long as the sun is shining high in the sky, and nearly dead-on to the panels, a water pump using 800 watts could theoretically run continuously with eight panels rated for a total of about 1,000 watts. Get more panel power, to play it safe, if you expect long-use water pumping. The voltage will often drop to the mid 20s when using high power, holding it there (the batteries will be fine under this load). Even if it drops from 29 volts suddenly to the low 20s, that's not the true voltage of the batteries, just a temporary reading. It's safe.
However, if clouds roll in while using the water pump continuously / plenty in a long-term duration, you could damage the batteries. With the sun shining, the voltage will hold at a safe zone. What I can't tell you is whether the battery plates are being used up when using the system during sun. Someone at the battery company said that the power is "being skimmed off of the top" of the batteries when the sun is shining. It doesn't tell us whether there is any plate deterioration, or less deterioration, or just as much as when we take power at night.
If your too-small system is a struggle, use electricity when the sun is shining, a no-brainer. If you provide large, or many, water tanks for trib purposes, just fill them with water when it's sunny, a no-brainer. If three days of clouds move in, and the battery voltage drops to 24.4 (the reading with no electrical usage at the time) in the dark of night, the water pump becomes a serious issue if the water demand, coupled with other electrical demands, is great. It's not the time to do laundry or take showers. Battery companies maintain that most battery damage (aging) occurs by bringing the standing voltage to much less than 24.4. Batteries can be ruined in a year or less by doing so too often and too deeply. On the other hand, if the voltage is at 24.4 and the only thing running is a 50-watt laptop, one can use it all day long and see no change in the voltage.
A battery at about 24.0 is "dead." But it's not really permanently dead. It can be re-charged for a certain number of times. But there is a limit on how many times the pack can be drained to 24.0 before suffering a fatal blow. However, if you see that the voltage meter has dipped below 24.0 during high electrical usage, that is not the true, standing measure. We can say that the voltage registered on the volt meter is a measure of the exterior edges of the battery plates; the interior of the plates have a lot of energy that can't get to the outer edges as fast as the energy on the edges is being used up. So, after the voltage drops below 24.0, it comes back up again soon after high electrical use ceases. If it doesn't come back up, you've drained the batteries too deeply. You and others will need to keep eyes on the batteries regularly with lots of people in the home. You might be hen-pecking them, asking that they take shorter showers, or something. Somebody has to be the bad-guy boss.
I'm reading online that a 1 HP deep-well pump uses 8 to 10 amps, or about 1000 - 1200 watts (multiply amps x 120 volts to find watts). However, I'm also reading that 1 HP is equivalent to 746 watts, though another says 2,000 watts. It's hard to trust google these days, so much disinformation. I suppose the 746 watts is for a jet pump (like mine) while the 2,000 watts is for a deep-well pump. Call the pump company to inquire about your pump, before buying it, and have your own wattage meter too, so much fun.
Although I have a circular saw rated at 20 watts, it's not always using 20 watts. If it's cutting thin plywood, it's using less power than when ripping 2 x 10s. In the same way, your shallow-well pump (20 feet up or less) might use as few as 500 watts at first (I'm just guessing), and more as the pressure tank builds in pressure. One option is to set the pump to shut off at 30 psi instead of 40 or 50, saving an enormous amount of battery power if you have high water demand. You can manage with a smaller pump (1/6 HP does a lot of water for home use) if pumping into an open tank.
Having an open tank(s) is a very good idea. You can have a shut-off valve at the tank so that, when it's shut, the pump fills the pressure tank instead. You must not, CANNOT, take the chance of using an open tank without an automatic valve that shuts off when the water reaches a certain level (such as the one in your toilet tank). Ask your farm supplier for one of these, because they are used to automatically fill tanks for livestock.
My four batteries can handle a toaster (about 1000 watts) for several minutes consecutively without dropping battery voltage critically when the sun is high. But that's because my eight solar panels (rated for 1040 watts combined) can produce 800-900 watts even when the sun is not at its best angle to the panels. I would not counsel you to choose less than 1000 watts of panel power, if you're unable to afford more. Rob an old lady if you need to, just get at least 1,000 for a family of four for trib purposes, because that's skimping. I was okay with it, LIVING ALONE. And I have a shallow well. If you're as far north as the Great Lakes, 1000 watts may not be enough for winter. Rob the old man too, just don't skimp on panels.
If you wish to water the garden for an hour or more, you can do it at midday so long as the panel power meets the pump requirement. If your pump uses 1200 watts, get about 1500 in panels, but more if you think you'll be watering the garden several hours at a time every few days. A day only has a few optimal hours of sun, and, often, those hours happen to get the clouds. Inquire as to what batteries are best for long bouts of garden watering. If you're going to depend on a garden for food, you really need to do your homework before you buy.
Theoretically, a 130-watt panel provides about 130 watts when the sun's angle is straight on, when the sun's position is at its highest, and when the panels are new (they produce less with age). Panels in Arizona in summer won't get 130 watts because hot weather makes them operate less efficiently. Panels in a cold weather work most optimally. The further from the equator one's location, the less the panels can get maximum sun from a "high noon" position, albeit a position of one or two o'clock is nearly equivalent to high noon. Each 130-watt panel can only run two 60 watt bulbs at peak sun conditions. It's so precious little.
In Canada, the sun on December 21 is significantly lower than 45 degrees. The amount of atmosphere that obstructs sunlight becomes significant between 60 and 45 degrees, but is critical at 30 degrees. Even in southern Canada, the sun reaches as low as the 30s. That's why Canadians will need a generator that will be sure to start at temperatures 10 below zero F. I purchased a new Yamaha model small enough that I can carry it into the house to warm up, if need be. In other words, if you get a monster compressor, used and unreliable, that won't fit through your front door, you may have a problem in winter. On the other hand, a small generator like mine would over-load when a motor turned on, so it's useless for most water pumps and probably fridges too. I got the generator only to charge the batteries, however, and after doing that, I can run any motorized equipment through the solar-power system.
The Yamaha always started several winters in a row, but the makers left loose screws all over the place, not a good sign. A wicked generation will booby-trap products to force us to buy parts early, not a good thing for our trib purposes. One loose screw that I couldn't get to with tools on hand, after only about 60 hours of operation, required taking the machine to the repairman. Maybe don't get Yamaha for yourself.
At the US-Canada border (not including the cloudy west coast), they say that solar panels achieve, on an average over a 24-hour period in the winter, the equivalent of one to two hours of sun directly overhead. Using a string of panels capable of providing 1,040 watts max at high noon, you'll get about 1,000 watts for one or two hours. So, in that environment, you will be able to run a 1200-watt pump for more than an hour daily (ON AVERAGE, not necessarily every day), but nothing else. You might become the electricity miser, not a new thing at all in the world of solar power.
I have four batteries dedicated to DC circuits only, which runs the lights and the computer. The power from the other four is run through the converter i.e. converts battery DC to 120 volt AC. I wired the lights with direct DC (even though it costs more for larger wiring) because the inverter uses 100 watts to power a 50-watt laptop, which I use at least eight hours on a daily average. In other words, this big inverter has a dismal 50-percent efficiency rate when providing small wattage. The efficiency rises quickly into the 90s when 200 or more watts are in use at any given time.
[Update January 2021 -- As 120-volt light bulbs are now all of low wattage, I think one can just forego DC lighting altogether, even if your monster inverter gets only 50-percent efficiency at low watt usage. So, if you have four bulbs on for hours nightly with a total of about 36 watts per running hour, and if the inverter doubles that amount, it's not going to be a killer situation for the batteries on most nights if you're using eight batteries. You'll get away with it with four batteries on sunny days, but for the cloudy periods, that's why you should purchase at least eight batteries. I'll leave the DC-wiring section below for anyone who might benefit from it.
I was in the habit of shutting off the inverter each night, taking my chance that a daily re-booting would not cause a failure of some sort, and there was none. I suppose there's always a chance that yours might. It's your call on whether you want to shut the machine down nightly. It would be such a shame, really, to purchase such an expensive system if just one thing goes wrong that spoils it all. That, at least, is a good reason to have DC wiring, no equipment needed, just wire straight from the batteries.
I wrote this chapter for the person on the poor side. You don't need this chapter if you're rich. You can have a trouble-free system if you're rich. End update]
I'm using LED bulbs at some $15 or even $20 each. They are equivalent to about 25 watts in brightness (as shine the old-fashioned bulbs), but use only three watts. They have a long life, however, to make up a little for their cost. The problem is, I can't get 24-volt bulbs in my area any longer. As 12-volt bulbs are the norm, you can either make your solar system into a 12-volt one (easy to do), or, if you prefer a 24-volt system, you have the option of using it with 12-volt bulbs. But it's "dangerous." That is, you can wire two 12-volt bulbs in series from a 24-volt battery pack so that the two bulbs combined can handle the 24 volts without blowing out a bulb. But when one bulb dies or is damaged by some physical impact, the other will blow out because it can't handle 24 volts. That's what's "dangerous" (i.e. you will be out two bulbs, but there is no fire hazard).
It seems that simply changing the battery system to a 12-volt one is best, yet, as bad fate would have it, the lower the voltage, the larger the wiring needed in order to keep the volts from shrinking by the time the electrical flow gets to the bulb. The bulbs are already low in light, but reduced voltage will dim them even more, and here I am no expert because my wiring was never a problem i.e. I can't tell you what size wiring might be a problem for you. You could probably live with slightly-reduced brightness, but, frankly, I don't know whether there will be sufficient lighting in a bulb socket furthest from your battery pack.
Your home is likely wired in 14 or 12 gauge wire, but my inspector made me use 10 gauge (larger than 12 or 14) for a 24-volt system. The lower the voltage, the larger the wire diameter needs to be in order minimize voltage loss with distance down the wire. This is why I chose a 24-volt system versus 12. You can go with 48 volt with your system (it's easy to rig up), and get away with your present wiring, then reduce to 12 volt at the light bulbs by using a volt-reduction device. A smaller wire gauge than 10 would probably be fine for most of your bulbs, but long runs with 14 gauge could be a problem with low-volt systems. The good news is that larger wires are not needed due to safety concerns; there's no danger in having small-diameter wires. There's info online to help you sort this out.
Here's a heads-up: if you make the bedroom lights into a DC circuit, for example, the bedroom receptacles will likely be DC too, useless for any AC usage. That potential problem goes for any part of the house. There are so-called transfer switches that allow you to chose whether your wiring will get AC or DC. You can have DC by night, and AC by day, at the flip of a switch.
You need deep-cycle batteries, not car batteries. Deep-cycle batteries are made to be discharged up to 50 percent their capacity without suffering much damage, and these can last ten years or more (the more they are discharged, the more they age), or upwards of 1000 cycles of discharging from full to 50 percent. You can clearly see that one 50-percent discharge daily, on average, gets the batteries fried within about three years.
Solar batteries are rated in amp-hours, the number of amps the filled batteries can provide, when new, for one hour of usage. Mine are rated at 530 amp-hours, if one full discharge (between 100 and 0 percent) occurs slowly, over a period of 100 hours. The shorter that period of full discharge (i.e. the faster the electrical flow), the less total amp-hours we get. So, the Surrette battery company appears to promise that four batteries (set up as 24 volts, 6 volts per battery) will provide the equivalent of 530 amps x 24 volts = 12,700 watt-hours over a discharge lasting 100 hours. The battery companies may ALL be exaggerating a little, however, in their heat to draw in the most business.
We are directed to discharge only half the battery capacity, meaning that one cycle of discharge gets us about half the 12,700 watt-hours above. From that math, I would guess that 6,000 watt-hours is the maximum, though my gut tells me my new batteries were not raking in that much even while draining the batteries very slowly on a laptop using merely 50 watts DC. To play this on the safe side, let's use 3,000 watt-hours per cycle, on average throughout the battery pack's lifetime. If the battery company promises 1,000 cycles, that's 3,000,000 watt-hours total until the batteries are virtually dead (virtually all the plates have been used up). That's how you should do your math for your particular situation. Figure out your daily need, then multiply by 365, and finally that tells you how many years the one battery pack will last you, or how many batteries you should get.
If your fridge runs on 200 watts, but runs only 20 minutes (.33 hr) per hour, that's 200 x .33 hr = 66.7 watt-hours. Every day, that fridge will receive 66.7 x 24 = 1600 watt-hours (or 1.6 kilowatts per hour if you like that term better). For a new battery pack of four batteries like mine, that fridge will take the pack through one cycle every three days, roughly (play it on the conservative side), and, on average (i.e. not a new pack), about every two days. That fridge alone will kill your battery pack after about 5.5 years, but you get double that time with eight batteries. The big question is: do batteries cycle if the sun is shining and providing all the electrical needs? I don't know. It's possible that the electrons do not enter deeply into the plates, or maybe not at all. This is a question for you to ask the people you purchase the batteries from.
If your tribulation endurance lasts four years, you can count on at least two such fridges on one battery pack of eight. Then do the same math for your water pump(s), light bulbs, and for whatever tool work you think you'll need. After that, you can add in the luxury items such as the laundry machine.
I don't know whether you can run anything on the panels alone (i.e. without batteries installed at all). The solar panel wiring goes to the batteries, but the batteries are simultaneously connected to the inverter (the machine that feeds the house). It's therefore possible that some inverters take power from the panels before the power is run through the batteries. That would be ideal for saving battery life, but I'm thinking my inverter won't do that. Are there some inverters that feed off of the panels directly? I'm unsure, but perhaps a run-down or sulfate-ruined battery pack (if yours happens to get fried) is not altogether useless if it allows the inverter to catch panel power by day.
Here's Part 2 of a video , showing a battery-bank, off-grid system:
https://www.youtube.com/watch?v=gPycyuVJ_CgParts 1 and 3 are immaterial for those wanting to prepare a system off the grid.
You might purchase a solar system some years before the tribulation, and then take the risk of using the batteries during the tribulation, not knowing how badly they have become deteriorated. Batteries receive less power with age, and get "filled" sooner because they are not being filled to capacity. The battery charger stops charging the batteries when it thinks the batteries are full, and they appear full (to the charger) even when ruined. To put it another way: when the batteries can no longer receive power easily, the charger thinks the batteries are full. Ruined batteries have most of the surfaces of their plates covered in permanent (unremovable) sulfates that no longer allow electron entry into the plates. Only where there is no permanent sulfate build-up (during discharges) do electrons enter the plates, and once those areas are full, the charger thinks the batteries are full. The less power the battery can absorb when "full," the less you'll have per cycle. It's the same as saying that the battery shrinks in size with age and with bad management.
The good news is that my batteries have lasted nine years. The bad news is I live alone i.e. use little power. If there were five people here, I doubt very much that eight batteries would have lasted until now.
During regular charging, the sulfates come off and the plates are cleansed, but, the battery people say, if the sulfates are allowed to remain on the plates too long (long cloudy periods are the culprits), they will no longer come off. This is why it's risky to have batteries linger in the half-charged condition day in and day out. They need to be brought to the fully-charged level fairly regularly, but, the problem is, you never know how many sulfates are remaining on the plates when the batteries are supposedly fully charged. There is probably a way to discover how good or bad the batteries are.
If you undersize your panel power, or oversize your battery pack(s), you could have a kill-battery situation that won't get you the promised number of cycles. If you test a small system at the worst sun-level period of your year, while you're still able to make purchases, you can buy either more panels or more batteries, whichever of the two you still need. That's the best way to get it right. Create a mock tribulation situation at your place starting with a system that you think is too small, and then buy only what more you still need. If you feel that you are in a rush to buy, you can opt to buy plenty of both batteries and panels, because you don't need to use them all. You can always give your spares to others that might need them. As I understand it, thin film can be applied to any substrate; plywood, for example. You can buy extra thin film and leave it uninstalled until needed. For trib purposes, thin-film seems the best way to go.
The obvious problem with buying more batteries than you need, and leaving them laying around in case you need them: they must be charged from time to time, once they have dropped down to about 75-percent capacity from just hanging around unused. The way to do this is to bring the panels wires first into a transfer switch, then wire from the transfer switch to both the spare batteries and the in-use batteries. A transfer switch won't allow both of those systems to be charged at the same time. You choose which one gets the juice by the flip of the switch, easier than pie.
However, online criticism is that batteries placed in storage on a repeated re-charge basis without any electrical outflow suffer deterioration too. The fix for this is to simply not call them the spare batteries, but to use them on a part-regular basis as part of the power system. For example, you can use as the "spares" for summer by simply connecting the two wires of the inverter to them. Then, connect the two inverter wires back to larger, regular battery pack for the winter. In the meantime, you use the transfer switch on any sunny day to re-charge the on-standby pack (needs doing every couple of months only).
I don't mean to scare you, but neither should you be flippant with a pack of batteries. Though there is piddly amounts of power for our usual daily needs, them batteries are packed with killer power. Be careful; know the dangers. It's not dangerous to touch a 24-volt battery terminal WITH YOUR HAND. But try being careless with some steel tools near the terminals, and you could become a first-hand witness on how sizzling hot the power is inside of those batteries.
Batteries die a slow death, even aside from sulfation, because their plates / terminals are thinned by the cycling process. If even one battery is bad, the entire pack will suffer...which would be a good time to use any unused batteries you had purchased as spares. Battery companies have a fix for stubborn sulfation, by charging "hot" at 31 volts (for a 24-volt system) for as long as it takes to burn off the sulfate crust, but if this so-called "equalization" process isn't done often enough, the crust becomes permanent. Follow the manual of your batteries.
Charging at 31 volts produces a lot of hydrogen gas along with oxygen, very explosive. You don't want sparks inside the battery compartment at that time. Make sure all connections to battery terminals are tight, and don't put any pig-tailed wire connections in there connected merely with the screw-on plastic covers. Use the better connectors (or solder your joints) that are more sure to keep the pig-tailed wires together, or, much better yet, do not have any wire-to-wire connection (wire-to-battery only) inside your battery compartment. Really, it's dangerous if the connections become loose, and they could become loose if you're in there moving those wires aside now and then, or changing their hook-up locations from battery pack to battery pack.
Batteries that require no maintenance are more money, and don't have acid hang-ups. If you can afford only acid batteries (need maintenance), then I say too-too-too-bad, you will regret saving the money. That was the choice I made, resulting in a big hassle.
I don't have a perfectly tight gasket (it's home-made) around the lid of my battery compartment, which allows some battery fumes to get through during a charge of 31 volts, or when the sun shines straight all day long (batteries get warm on such days, and release more fumes). The fix was to install a small fan as part of my 2" exhaust tube extending from the compartment to outdoor air. There are safe (sparkless) 2" fans made for this purpose that run on low energy of about 10 watts; they can easily be programmed to run only when good sun is shining (they're not needed during cloud cover).
Even though the gasket still leaks a little, the fan probably doesn't allow fumes to escape into my house space...until the fan shuts off (as soon as a cloud covers the sun, and when I use a lot of power momentarily). Often, when the fan first shuts off, the batteries (they can go on "boiling" a while after the sun stops shining) are still putting out a lot of fumes through the battery caps, but at least the fan greatly minimizes the fumes into my air space. I have a second pipe going to the outdoors, not on a fan, because the fan, when it's not running, doesn't allow air past it. Play this safe. Hydrogen is the most explosive gas, and probably not good to breath (its odorless).
To be sure that all hydrogen gets out of my small battery room, I have a tube through the ceiling that takes gases out to the attic. It would be safer to take this tube through the roof, but I've been lazy. I figure that small amounts of gas in the attic will find their way out, a good reason to have at least one air vent high up on the roof.
The ceiling of my battery room does not have cracks into the walls, for obvious reason. I have sealed (with caulk) the inside of the compartment so that gases do not enter the walls. Imagine a firefly getting into a wall that's built up with trapped hydrogen. Yikes, is a firefly sparky enough to cause an explosion? I don't want to find out. Be careful, think about what you are doing with your battery compartment and the room that you put it in. Do it right especially when there will be people living with you.
I haven't been running my fridge and freezer for most of the nights, and may be saving only 15 percent in electricity, but this is not what's important. My freezer operates on about 600 watt-hours daily (equivalent to 600 watts used for one hour), and perhaps 500 watts daily if shut off for 12 hours nightly. The important thing is that more than half of the 500 watts is acquired from the sun, possibly leaving less than half for the batteries. The less the batteries are used, the less they stand the chance of sulfating (unless you leave them sit in a low-charge state).
Testing with the watt meter (every solar-power monkey should have one), which keeps track of total wattage used on an on-going basis, the 5.5 cubic freezer I have, rated for 193 kwh annually, used up only 23 kwh hours over 46 days from July 1st to August 15 (in a house not air-conditioned but in a northern climate). That translates to 500 watts exactly per day, or 186 kwh annually...but it will do much better in all other months because they will all be cooler months, and besides, the freezer is placed in the cold garage as soon as bear season is over. It stays out there until April. It's working for me. The garage door to the house goes into the kitchen, and so the freezer is handy just outside the door. I barely turn it on all deep winter (start of January to end of March). The fridge manufacturer recommended not putting it outdoors in winter, but I've taken my chances over some years. Other freezers may be adversely affected, just a warning.
[Update January 2021 -- It's a good thing, maybe, for you, that I used it in the garage. This freezer did experience a motor problem, probably due to leaving it outdoors (it gets to -35 C here). When taking it in the house one year, the unit, after running once, would not go on automatically until the motor cooled down sufficiently. The unit would automatically try to run the motor every couple of minutes, but it would not start until a couple of hours had passed. You might not get so lucky. I rigged it up to work manually from a plug outlet tied to a wall switch (flipping the switch was equivalent to unplugging it); I started it that way three times daily for a couple-hour run each time, which did save lots of power but caused the breads to thaw repeatedly, though most foods, meats and vegies, stayed rather hard.
Actually, it was an ideal situation for me because I was running it indoor as little as five hours daily, whereas, if it was working normally, it would have run for as many as eight. But, the motor would not start again at all after a couple of years more. As it turned out, it would not start at times even after leaving it off all night, meaning it was not a hot-motor problem, but what the built-in sensor thought was a hot-motor problem when in reality the freon system had screwed-up in some way. So, best thing, probably, just in case, don't use a freezer in extreme cold once the power to buy another one is gone. If I had wanted to spend more money on more solar panels, I would have saved that hassle, but I planned on going off solar, to the grid, and did so a couple of years ago. I feel I'm back to normal again, but if I had to go back to solar, I'm more than half prepared mentally and on the skill factor. End update.]
The freezer manual tells that its thermostat setting should be at about 0 F (-18C). There is a bacteria said to grow in foods from temperatures of about 5-10 F, but if we sufficiently cook food, bacteria will be killed. I haven't gotten any food poisoning with a "warm" freezer. In other words, you can save power by having a warm freezer; just be careful with the food.
The freezer has 1.4 amps and 115 volts on its tag, amounting to 161 watts (multiply the first two numbers to find watts), and yet a watt meter ($25-40) shows that it starts up at 89 watts and eventually comes down to as much as 79 watts after running for a while. It appears that we can't trust those tags at all times. Get yourself a watt meter to know for sure what your appliances run on, even if you have a huge trouble-free system that at the start, because you never know when it will turn into a small system for one reason or another.
With heat-exchanger tubes (on the back of refrigerators) located in the cold, they will release heat more efficiently, requiring the fridge to operate less time. Plus, the colder the fluid, the better it will absorb heat from the freezer's interior. The potential problem was that the chemical in the tubes may not liquefy when too cold, and may therefore spoil the heat-exchange process. I called Danby's tech department. He said without doubt that cold temperature does not adversely affect the operation of the heat-exchanger tubes. Below is a webpage with this general topic telling that cold temperatures may or may not kill a freezer's / fridge's pump, but then the freezer can be turned off in the coldest periods (at the risk of forgetting to do so). I didn't turn the freezer on until the outdoor temperature climbed above 25 F (-5 C). The motor/pump seems to work immediately well at that temperature, but I've resisted turning it on at colder temperatures.
http://www.refrigeration-engineer.com/forums/showthread.php?5331-Freezer-operation-in-my-garageBoth the webpage above and below say that extreme cold kills the freezer's insulation, making the unit require more power in warm months. Is this an online myth put out by electric companies? Some say they have operated freezers in temperatures well below freezing without failures. Where do we find what is rumor verses what's true? Hopefully, your fridge company. Perhaps a good safeguard is to use your old freezer outdoors in winter only (bad insulation will then be less problematic), and to purchase a new one for indoors. If the pump goes in the outdoor one, it can still be used in cool/cold weather. If it holds water, use it as a tank...bonus with its own lid to keep out the flies.
http://www.ehow.com/info_11416259_freezer-work-unheated-garage-winter.htmlWhat we can do, if we think it's worthwhile, is to disconnect the heat-exchanger tubes from the back of the fridge. It's counter-productive when the tubes release heat right beside the fridge. The colder the air around those tubes, the better the system gets the heat out of the fridge. I don't see why one couldn't re-locate the tubes outdoors, or in an unheated space under the floor. I have both options. It would require a few feet of extra tubing to be soldered on, but the fridge repairman can either do it, or tell us how to, and it's going to include the need for more freon. It's a toss-up on whether this will be worth the expenditure, but I thought I'd pass it on in case you're forced to be a power miser. My freezer, and I assume many newer units, have the heat-exchanger built inside the walls of the unit so that the tubes cannot be accessed. In my opinion, this is a lousy way to release heat, in a trapped space as close as possible to the cold box.
I'm being perhaps too detailed, but I'm keeping in mind that you may have this page saved in your computer during the trib, and may need to appeal to some things within it. You may not be able to get online at that time.
Your system will only be able to provide, in AC power, what its inverter can provide. The higher the inverter provision, the higher the inverter cost. My Outback inverter can provide up to 3500 watts at any time. While I never use that much, it's helpful for motor start-ups. Some start-up surges can come near to 3500 watts. If your inverter can't handle your surge, the breaker will trip, meaning you won't be able to use those motors with the breaker too. If you bypass the breaker, you're not only risking a house-fire hazard, but perhaps risking a breakdown in the inverter's sensitive parts (the electronics parts especially). But, for all I know, an inverter will not be harmed by a split-second surge with watts beyond what it's able to handle on a steady basis.
Two motors will not go on at the same split-second but rarely. The chances increase with lots of people in the home running the water pump. It's your call on whether you want to pay a lot more money for an inverter that can handle the pump and fridge motors going on together. If two pumps simultaneously shut off the inverter, it's just a matter of turning it back on again; it's not going to do damage, if you have the protection of a breaker. By the way, if in the trib your inverter's breaker shuts off while cutting with the circular saw, try cutting slower.
Ideally, you want to avoid fuses (as alternatives to breakers) in the trib unless you have lots of extras, but where you have motors that challenge the inverter's capacity, a time-delay fuse (won't burn out due to temporary / typical motor surge) instead of a breaker makes a lot of sense, at first thought, anyway. I don't know whether a time-delay fuse can be used for an inverter, or even if anyone makes a suitable one for the purpose. My inverter does not come with a built-in breaker, meaning that I install one (between batteries and converter), meaning also that I have the choice of using a time-delay fuse...unless the inverter company says that surges above the inverter's watt rating can damage the unit in some way (maybe not, we hope).
As far as the equipment beyond a breaker or fuse is concerned, a time-delay fuse is equivalent to using no breaker at all. You do not want a time delay of more than a split second, in any case. Not all time-delay fuses are the same. I assume that time-delay fuses have their limits on how much surge they can handle before burning out. Even if the company allows a time-delay fuse, don't oversize one so that it slowly kills a sensitive part of the inverter. The best option is to stick with a breaker for an inverter that's more than large enough to handle one motor. My 3500-watt unit never gave me a water-pump motor problem, but that was with a 1/2 HP jet pump only.
By the time that you read this, someone may have put on the market a new device that simply eradicates, or gobbles up, a large motor surge before the power moves into a piece of equipment. I wonder why they haven't invented one already.
You can use the DC power straight from the batteries as easily as hooking two wires to two battery terminals and to your end use. If your four batteries are prepared as a 24- or 48-volt system, you can yet get 12 volts from them by connecting one wire to the positive terminal of one battery, and to the negative terminal of the battery directly beside it. If the latter wire is connected to the next battery (three in all between the two wires), you'll get 18 volts. While that voltage is not needed for most things, my laptop works on 19.3, and could work on the 18 too.
However, it's not healthy for the battery pack to use only two or three batteries on a regular/daily basis while not using the others in the pack. It's aging two or three batteries only, and, I think, this wipes out the potential of the unused batteries. I keep reading that the entire pack is only as healthy as its sickest battery. But if you have a short-term / low-use need for 12 or 18 volts, you can get them from a 24- or 48-volt system at any time with no devices needed, just some wiring.
To alleviate the problem for 12-volt uses, you can alternate from one pair of batteries to another so that all batteries in the pack are used roughly equally in time. Every time you go in and move the wires to different battery terminals, expect sparks at the terminals.
The sales people say that we can't combine a new battery pack with an aging one without some diminishment of power from the new pack, though I don't know whether any damage is done to either pack. Just so you know to inquire about this (the Surrette battery company allows the addition of new batteries when the others are not more than a year old). I suppose that one could age the new pack for a while until both packs can be linked together. I decided to keep the two sets of four batteries separate from one another for fear that, if all eight were used in one system (all eight charged at once), winter sun might not get all eight charged enough to prevent on-going battery damage.
Using two separate battery packs requires a transfer switch (mine's small) that decides (at the flick of a switch) which battery pack gets fed the panel power (there needs to be a "brain," called a battery charger, between the panels and the batteries to make sure the panel power is made appropriate for entry into the batteries). Simple enough. My transfer switch (very small) was purchased at an auto-parts dealer, made for 12-volt systems that can therefore handle 24 volts as long as it can handle whatever total power your solar panels provide to them. Only one set of batteries can be charged at a time...unless an extra charger is installed, in which case, I think, one needs to split the full number of solar panels into two separate circuits, one per charger.
I did bring two sets of wires down from the panels, one set per four panels. Having these two panel packs gave the option of one panel pack per charger, but also offered an extra capability which I will explain to you in case you absolutely need it, AS LONG AS YOU KNOW THAT IT COULD BE DANGEROUS in more than one way. That second charger gives peace of mind in case one breaks down, but there's an obvious problem with having four panels only per four batteries. That's why I designed a special wiring method.,P> In this method, I send both panel-pack wiring to a transfer switch that itself allows the option of sending one panel pack to a second charger while simultaneously leaving the other panel pack at the first charger. This switch is necessary to give me the option of using both packs simultaneously to charge one battery pack or the other, a thing to be considered vital in a small solar-power system, yet IT'S POTENTIALLY DANGEROUS, so long as you know. The above switch wiring is not the potentially dangerous part.
All four wires (two power wires) from all eight panels were brought into a standard, round electrical box (the type used for home lighting) because eight panels total and their 10-gauge wiring is not so much power as to require a larger box. From the inside of this box, one hot wire from one panel pack goes to the right-side battery charger. The other hot wire from the remaining panel pack went to a second electrical box a few inches away, which holds the transfer switch mentioned above. A hole was drilled in the cover to this second box so that the handle of the switch protruded outside the box to allow me to flip it left or right. The handle has a center position that sends power neither left nor right.
The transfer switch has a central connection pole as well as a connection for both a left-side and right-side wire. The hot wire coming out the first box goes to the center connector of the switch, allowing one to chose whether this panel power goes left or right. The right-side option sends the power the right-side battery charger, the one above that already has the hot wire from the other panel pack. In other words, flipping the switch to the right brings two hot wires to the same charger so that it gets power from all eight panels simultaneously. I've never had a problem wiring the charger with two hot (DC) wires like this, and hope you don't either, but, for your sake, ask the company that owns your charger whether this is safe, because, whenever you touch two hot wires together, it should make us nervous.
I may have been lucky, for all I know, because, on each hot wire, I had four panels of the same make and power levels. But what would happen if you tried this with two wholly different panel packs? I frankly don't know, but, keep in mind, this is DC power, not alternating current. It could be safe all-around in that one panel pack simply adds amps to the second one...keep sailing, all's well, be happy. But there is another dangerous situation up ahead, and this one could be Hell. I actually deleted this section because I don't want to be responsible for your home burning down. Then I reconsidered conditionally.
Back to the transfer switch. From its left-side option, a wire goes to the second charger, meaning that the latter charger only has four panels maximum, and can never have eight. The second charger is wired only to the left side pack of four batteries; it can never charge the right side. As soon as I flip the switch left, the second charger starts to charge the left-side batteries. No problem, smooth sailing.
BUT, Jacko, the right-side charger is wired to both packs of batteries...how do you spell nerves on edge? Okay, but, whew, it can't charge both packs simultaneously, whew. That's because the wiring from this charger goes first to another transfer switch (don't you just love complication?), which chooses which battery pack to charge at any one time. This way, we can have all eight panels available to charge either pack. It's magical. It's what we want. It saves us from the scourge of only four panels per four batteries. We need the eight, and we may be willing to take the risks involved. Don't gamble unless you absolutely know what you're doing with this i.e. unless you know it's not a gamble.
Here is the POSSIBLE DANGER: it may not be permissible, nor safe for the two chargers, to have both chargers charging the same battery pack. If the right side pack is able to charge the left-side batteries while the right-side charger is able to charge the left-side batteries, what happens when they are both charging the left-side batteries? Does the house go up in flames? Do both chargers get fried?
The first thing I want to say is, the two hot wires at the same terminal may be fine if power is going into the batteries, but what happens when the batteries are filled? I suggest that the batteries should be grounded into the earth, wet earth (with a proper steel rod or plate that meets code). In this way, the power from the two chargers meeting at the same terminal might go into the ground, instead of heating up and melting, once the batteries are filled to capacity. The equipment (inverter and chargers) itself needs to be grounded to the earth, anyway, so the ground wire will be right there, where the battery wires meet the inverter.
The second thing I'd like to say is that there is absolutely no danger in the hot wires melting at the battery terminal if you have the transfer switches at their correct positions. If you do, then you never charge the left-side batteries with both chargers simultaneously. The switches are there to prevent that, BUT, you might forget to flip the switches properly, or you might be drunk, or who knows what, and you end up sending power to the same pack from both hot wires.
So, whenever you flip the second switch to send power to the left-side batteries, make sure you first flip the first switch to cancel power to the left-side charger. When you cancel the latter, you flip the switch to the right, resulting in the first (or main) charger getting power from all eight batteries, and thus the left-side batteries now get both panel packs (all on one wire, happy-happy). If you flip the second switch to the right, all eight batteries will charge the right-side battery pack (all on one wire, happy-happy).
To put this in short: always keep your eye on the first switch; never have it to the left side if the second switch is to the left side. What I did was to be stern (never drunk) by always checking the first switch before flipping the second switch, and never flip the second switch before checking the first switch. And keep your head on straight; don't get confused.
Having said that, let me reiterate: I don't know whether there are any dangers in this set-up, but just in case, I made a big deal about the possibilities. You go find out if there is danger, how great the danger might be, and if there is a way to prevent it. One way to solve the risk is to just wire all eight panels, as one pack, to one charger, all going to all eight batteries as one pack, simplest and safest. But, as was said, you might have a problem getting all eight fully-charged, in winter, for weeks at a time, and this is not healthy for the batteries. By having the battery packs split into four per pack, you can just keep the left-side pack charged and on stand-by (maybe use it for light loads like lighting), while using the right-side pack as the main powerhouse.
You can perhaps check for danger, to ease your mind, but powering the left-side batteries with both hot wires early in the morning when the incoming panel power is as low, say, as 40 watts. If, after some time, the hot wires (both connected to the same terminal) get warm, you have a danger, especially if they get warmer as the sun gets higher in the sky. This check is best done with filled batteries, I assume.
You should absolutely have fuses, if you try this system, on all wires exiting the two transfer switches. My understanding with household AC power is that, when two hot wires touch and spark/melt, the breaker is tripped (sometimes before melting), and so the fuses (a small hassle only) may be all you need for full safety and peace of mind...if you get the right fuses. For example, if your panels are putting out a maximum of 7 amps, the correct fuses would be slightly more than 7 amps.
I just want to add that I don't see why a fuse burns out, or a breaker trips, when two hot wires meet, since neither wire is drawing power, but rather the power is crashing where the wires make contact. Perhaps it's due to the kick-back of energy, in reverse direction along the two wires. The situation can be far softer, anyway, with panel power, than sparking or melting wires, depending on the load at the time. I would ask you NOT to be confident that all is well just because the fuses don't burn out, because the two hot wires making contact could restrict power flow through the panels and chargers so that some slow-but-sure damage is being done.
The best thing: just don't charge the same battery pack with two panel packs (can't get safer than that). And, have the fuses there in case you forget to have the two transfer switches in their correct positions, and these two things together should make the situation fine.
I accidentally allowed steel to make contact with two battery terminals at once, and it blew part of the terminal off as melted metal. That got my respect.
If you're using the batteries for nightly 12-volt light bulbs but with a 24-volt (four-battery) system, then consider using one 12-volt bulb hooked to two batteries and another bulb hooked to the other two batteries, and just make sure the two bulbs use up the same amount of power roughly. This would be a good fix if your 24-volt bulbs break down, and all you have left is the option of 12-volt bulbs.
However, if your 24-volt system has two sets of four batteries, and you're only using the one set for nightly for bulbs, you can readily see the problem. To solve it, wire the light bulbs to a transfer switch first, then go from the switch to both sets of batteries, and take turns using one set for some days, then the other set for some days.
A way to eradicate the problem altogether is to use a DC-to-DC converter ($100, probably available cheaper) to convert the power from ALL batteries from, say, 24 volts to 19.3 volts. And that's what I did to run the laptop. With a small adjustment using only a small screwdriver, this converter can convert to anything between about 14 and 23 volts, very handy / useful.
Ideally, you would have a wire at each end of your battery pack going into a typical but very small panel box with breakers. From that box, you could wire several circuits to anywhere in the house, and then just connect / plug the converter above into one of those circuits. Be careful not to repeat my mistake of having the DC wall receptacle beside the AC receptacle (couple of inches away) without a "DC" written on the one receptacle. I TWICE (great shame) plugged into the wrong receptacle and fried two converter units. Don't laugh because you'll get old too.
It's helpful to by-pass the inverter as much as possible because just one of its vital parts may burn out when you can't replace it. I wonder whether the company added a booby trap deliberately so that, after a certain number of hours on the "ON" position, regardless of how much electricity is obtained from it, something suddenly goes wrong with an expensive part needing replacement. Or, even if there is no booby trap, its remaining on the "ON" position 24/7 may somehow wear something down. The unit hums continuously, and so I felt good about shutting the unit off all night, every night. It never gave a problem rebooting (goes through a process), but any risk such as this one needs to be checked out by sharing it with a person at the company that has many years of experience at answering your questions truthfully. Always ask: how long have you been with the company, because people on the phones are often new to it.
My so-called "Mate" did go bad, and this is part of Outback's inverter system. The Mate is a separate item, optional, that allows one to program the inverter and the battery charger in various ways, very handy. When the inverter reboots, the Mate needs to have some of its buttons pushed to get it set up again, and, eventually, the buttons stopped working properly. I was lucky to be able to reboot the inverter in spite of this button problem. Similarly, the workability of the buttons on the battery charger became hit-and-miss, and eventually more miss than hit. If buttons don't work at all, the entire multi-hundred-dollar unit (about $500 for mine) is useless. This seems to me to be the typical booby trap: make the buttons vulnerable deliberately, and people will likely buy new chargers if replacing the button panel is half the cost of the charger. It's a form of grand theft because it's in the millions of dollars worldwide, per product.
A 24-volt system with four batteries only is a string of four batteries all wired the same from negative terminal to positive terminal of the next battery in the line. But when you add a second string of four batteries, you want to connect the fourth battery with the fifth one differently. This keeps the system at 24-volts even though there are eight (or 12 or 16, etc.) batteries. For a 48-volt system, all sets are eight batteries long. Diagrams are online, but make sure you don't get one where the creator/provider of the diagram made a mistake.
With solar, one needs to become a power miser. To save more energy in a tribulation situation, and to have better security in the meantime, it would be a good idea to wire the fridge and freezer straight from the batteries. I have a small fridge (57" x 24 ") drawing 130-135 watts from the inverter, but the inverter's poor efficiency at this demand level means that the fridge is taking over 200 watts from the batteries (when it's the only electrical thing on at the time). If the inverter is by-passed for both the fridge and freezer, not only would the inverter last longer before failing, but the batteries will last longer too. To run the appliances direct from 24-volt batteries, one would need a device made to convert 24 volts to normal AC power. Is it worth the cost? You decide. At least you have the option.
The problem may be that the converter's breaker needs to handle the momentary surge from the fridge / freezer motor. I've just called someone to inquire, and he says they don't usually make low-wattage converters to handle a large surge. The page below shows a 24-volt converter to a maximum 700 watts AC for $278 US (Apr 2016). Ouch. If it can handle the surge, that device can run both a fridge and freezer, with much to spare for other things. But is it worth the cost? You decide. This website has many different converters for all your expected needs:
http://www.trcelectronics.com/inverters.shtmlMy fridge is bigger than it looks because it has no freezer box. Although it's only 24 inches wide, it's fridge space is about the equivalent of a typical (with freezer box) 30-inch unit. Opening the fridge door just once (when it's not running) significantly reduces the time to its next start-up. That's because cold air is heavier, which pours out the bottom half of the fridge door while being replaced in the top half by the warm kitchen air. On the other hand, the freezer has the door on top so that all the cold air tends to stay inside when opened. If you're to have a large number of occupants in the house, the energy needed for the fridge will increase significantly. Figure this into your math for sizing your solar system; it could double the fridge's electrical needs. One idea is to appoint a fridge police with whistle for fridge-happy transgressors. As punishment, they need to refill the lead-acid batteries for a year unassisted, that'll teach them. On the third offense, they get locked up in the battery room.
I don't need the generator all spring and summer long. The message here is that you shouldn't necessary think that you'll be using a generator at all times. In my area, the months of October through to the end of December are heavily clouded, compounded by the sun lower in the sky at that time. Instead of using the generator, I shut the fridge down for the winter, and put the freezer outdoors. It's very doable for trib survival, especially if we'll be eating dried / canned foods. I used a camping cooler box as my fridge all winter because I've been home all day for the past nine years. I've basically lived a trib situation already, minus the ability to purchase at a grocery store. Whenever I need to get to the "fridge," out I go into the cold garage, several times daily (made me unhappy at first). I need to assure that the box comes into the house to warm up so that things don't freeze within it. I've learned to be okay with this. As I edit this chapter here, I have electrical grid power coming in just two days. I wonder what it's like to live normal again.
I purchased an "inverter" generator (Yamaha EF2400IS) that saves gas when it's putting out less electrical power, whereas typical generators (less money) tend to use roughly the same amount of gas regardless of how much electrical power they push. This means that gasoline is saved when charging in the later stages of any one battery-recharge session. Moreover, this Yamaha generator can be converted to run on propane, which I could do for tribulation endurance because propane has a long shelf life. The question is, how much money will be needed to purchase a propane tank(s).
They say that gasoline lasts for about a year before going bad, and that's only if treated with a conditioner. In my first year of owning a generator ($1,000 US), I didn't treat the gasoline (in the generator tank) over summer, and it started to run improperly. It's never been right since, and would probably have suffered more damage, to the point of inoperable, had I repeated the same neglect a couple of more times. The old gasoline has a negative effect at the carburetor, meaning: be sure not to let aging gasoline sit in the carburetor. Same as with your chain saw, run the generator until it runs out of gas if you know it will be on the same tank of gas for three months or more. It's not enough just to remove the gas from the tank; you need to get it out of the carb. Don't ruin your generator just before the trib arrives.
The winters, when the snow covers the panels way up on the roof, is when the generator might be most used. I created an opening through the roof in the middle of the eight panels. There is a place to stand on as soon as I get on the roof. For a wiper / scraper, I have a one-foot 2x4 nailed to the end of an eight-foot 2x4, and because there are four panels on either side of my standing spot, they amount to eight feet long on either side. The 2x4 scraper is long enough to wipe / scrape the snow off the panels. That's what I do, as many as a dozen times per winter. And that's why I don't use much gas for the generator. If you don't provide a way to wipe your panels clear of snow, it would be unwise. The wind and/or sun sometimes clears the panels for me. Those are the times I feel blessed.
You might like to have your solar panels on/near the ground if there are no trees between them and the sun. When not holding regular jobs, we will not be inconvenienced by turning the panels by hand toward the sun in the morning, then turn the panels to face toward the sun at noon, then turn them toward the sun again in late afternoon. To make this easy, have your panels suspended at the top of a steel pole, and arrange a method at the ground (e.g. a steel / concrete socket partway up the pole) for spinning the pole. People who hold jobs daily might purchase an automatic solar tracker, but then it's said that including just one or two more panels gives as much additional power as a solar tracker.
There are two ways to turn the panels toward the sun: 1) as above, by following the sun hourly; 2) by the tilt angle to the sky, whether facing straight up or at an angle, season-by-season.
I came across this: "...a panel that is one square meter and turn it 45 degrees away from the sun the effective surface is Area divided by 1.41." My understanding here is that the sun shining at a 45-degree angle is not half the energy as one might assume, but 1 / 1.41 = 71%, which is pretty good. Another chart had shown a 30 percent loss at a 45-degree angle.
The chart at the page below (page no longer in service) tells that a tilt angle 30 degrees away from the optimum angle reduces power by 11-12 percent, while a tilt angle of 60 degrees away from optimum reduced annual energy by 44 percent. If your panels are on the ground, or easily accessible higher up, you can arrange to change their angle to the sky with the changing seasons. I lose a lot of power in summer when the sun crosses directly overhead, for my panels are about 55 degrees off the horizontal (more vertical than horizontal).
http://www.usrea.org/documents/Solar-Module.pdfHere's some solar-incidence charts:
https://www.google.ca/search?q=solarIncidenceChart.jpg&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiquNeBp_bXAhUJ3YMKHe7tAEkQ7AkINQ&biw=1007&bih=450Propane is the way to go over gasoline for a generator. You can do what I did: buy a gasoline generator that can be modified to propane:
"Our do-it-yourself change over kits allow you to run your Honda gasoline generator on propane, natural gas, or all three. Your engine will last longer, start better in cold weather and even start next year when you go to use it in an emergency......If you have propane available you probably know you can store propane for years. It does not gum up, go bad, or pollute the air like gasoline does. Use the little bar-b-q grill type cylinders as shown above or up to the 1000 gallon ASME tanks."
(page now gone) http://www.propane-generators.com/honda-generators.htm
The following webpage is not a Yamaha dealer, but promises to provide me with a tri-fuel carburetor kit, allowing my machine to run on gasoline, propane or natural gas at the turn of a switch:
"...You could run the generator from the [small propane] cylinder while camping and then, when you come home, you can connect the same generator right into a natural gas line or just fill the generators gasoline tank and run. That's right. It's as simple as turning one fuel off and the other fuel on."Here's the tri-kit and how it works.
You run the risk of damaging sensitive equipment when running them off of a generator. My Chinese model generator ruined two computers, but Yamaha claims that its inverter-generator won't harm computers.
I didn't know the following, or at least I hadn't read anything so drastic on tree shading of panels, until my fourth year of owning a solar system:
If even a small section of a photovoltaic panel is shaded - for example by the branch of a tree - there is a very significant drop in power output from the panel. This is because a PV solar panel is made up of a string of individual solar cells connected in series with one another. The current output from the whole panel is limited to that passing through the weakest link cell. If one cell (out of for example 36 in a panel) is completely shaded, the power output from the panel will fall to zero. If one cell is 50% shaded, then the power output from the whole panel will fall by 50% - a very significant drop for such a small area of shading....Bypass diodes can be connected between panels in a system, and also between groups of cells in a panel so that the only power loss is from the shaded portion.
http://www.reuk.co.uk/Effects-of-Shading-on-Solar-Panels.htm
I'm not sure whether the writer is fully accurate. Bypass diodes might just be what you need. They assure that only the shaded parts of your panels lose power. In my case, a small amount of snow at the bottom of the panels, will render all the panels almost useless even though the rest are perfectly snowless. I've had to get up on the roof many times just to clear a wee-bit of snow ("hard shading:) that may have been melted away in a day or two:
Shading obstructions are considered "hard' when objects are in direct contact with the glass...Bird droppings, broken tree branches and wayward frisbees are examples of hard shading...Partial hard shading of one cell in a photovoltaic panel can create a power drop as much as 50%......Most manufacturers use bypass diodes...
http://www.wholesalesolar.com/Information-SolarFolder/solar-panel-efficiency.html
Should we or shouldn't we wire the batteries to a ground rod / plate? One electrical place I called, though not selling solar, said that batteries don't need to be connected to the earth, and yet I can't avoid grounding them to the earth because the panel box (to which the battery cables are connected) needs to be grounded to the earth for the other equipment that it services. I've wondered whether some battery energy leaks to the earth as a result. Here's what one man writes who sounds like he knows what he's talking about:
You don't need to ground batteries. In fact, if you are using an inverter, you better NOT ground your batteries......What can happen, is sneak paths develop, and you can trip Ground Fault Protectors - ( AC & DC ) or blow some of the internal protection fuses in inverters.
(page gone) http://www.solarpaneltalk.com/archive/index.php/t-1414.html
I don't understand that, but thought I'd pass that along.
My thinking is that lightning is more attracted to the metal frames of solar panels when the frames are more positively charged (the ground is positive), which is why I temporarily disconnect the ground wire at the electrical panel when lightning storms approach. In other words, I don't want solar panels acting as lightning rods, and moreover don't want a lightning strike on the ground near my ground plate to enter any part of my solar system through the ground wire, wherefore I just disconnect the ground wire (with the turn of a screw at the electrical panel) as soon as it enters the house. This is an important precaution you can take in the trib, if you think it's wise for your system. If your ground rod/plate is near a buried part of solid rock, lightning, if it strikes the wet solid rock jutting above ground level, could enter the ground wire. My ground plate is as near as a foot from solid rock.
I've read those who opinionate that the panels need to be grounded to earth in case of lightning, but my ground wire from the frames of panels is just 10-gauge, not thick enough to transfer the power from a direct lightning strike. Some insist that the secondary use of the frame's ground wire is for lightning protection, and that 6-gauge wire should be used, but I don't think 6 is large enough, anyway, for even a small strike. The primary purpose: "Grounding the panels is a safety feature to prevent electrical shock in case the wiring touches the frame." I figure that my panel frames will never have an electrical current.
Some say that lightning rods can be installed higher up on the roof than the solar panels, but even that makes me nervous, as a fork in the lighting can hit a panel once the entire lightning beam has been attracted to the lightning rod. I'm thinking that if the panels are not grounded at all, the panels will simply hide, invisible from lightning. Why have a lightning rod to attract lightning? You need big "wire" too, as thick as your finger:
I do not have a copy of NFPA 780-2004 which explains lightning protection procedures. Hope somebody can answer a few questions. I am connecting a lightning ground rod to a cross on top of a church. The print specifies that the lightning ground wire be run INSIDE the building through emt and that the emt should be spaced 6ft from any other wiring or metal structure. It also says that the ground wire be #1AWG [= size of wire]. Now first of all, I didn't think lightning protection was allowed to be run indoors. Nor does it even sound like a good idea. And the #1AWG seems a bit undersized. Anybody have any input on this? "I don't use any part of my solar system during lightning storms (i.e. I shut off all power to household items). I shut all breakers down too. Just in case. I paid too much for this equipment, shutting it down a half dozen times annually for an hour or less is not a chore.
Electricity runs from negative to positive...except in the case of batteries, because when they first assigned positive and negative charges in the pioneer days of batteries, they got it backward. The scientific establishment kept it backward to this day for convenience...meaning that what they call the positive terminal of a battery is really the electrically-charged, or negative, terminal.
If you're like many who loath to purchase arrestors / suppressors (some say they are unnecessary / useless), you may find yourself trusting in circuit breakers and fuses for trib insurance. When lightning arrestors are being discussed by solar-power people, the primary danger may be from electric-grid wires in the area (because many people on solar are also on the electric grid), but in the trib we can disconnect from the grid. Having two circuit breakers in any electrical line might (I wouldn't know for sure) act as an effective "lightning arrestor" (so long as you shut the breakers off in a storm). If the lightning's power jumps the first breaker's gap, then hopefully, there won't be much left to jump the second breaker's gap (but we wouldn't know for sure, and there's no way to test it).
Here's an article on battery charging.
http://www.energyalternatives.ca/SystemDesign/Chargers1.html
There's a global sun-hour map at http://lreese911.tripod.com/sitebuildercontent/sitebuilderfiles/solorpower.pdf
To make solar panels work more efficiently, one needs to remove the heat from their surfaces. I don't see why they don't make solar panels come with a tiny gap between the glass and the cells, then blow air through that gap to remove the heat. The fan size (i.e. the wattage needed) would be small if the air gap is in the range of 1/32nd of an inch. Air would just fly through that gap even with a small-power fan.
What they don't acknowledge is that heat formed above the silicon surface (the part struck by sunlight) is made of incoming solar electrons (they don't view heat this way). The entire purpose of the solar panel is to get the captured electrons (of the atoms struck by sunlight) as excited as possible -- as high and as numerous as possible off of the silicon atoms -- so that the atoms become positively charged (for as long as the electrons are excited). That positive charge causes electricity to run in a circuit from panels to batteries. That's what we want.
If one sends an air current fast across the excited electrons, some of them could be taken away by the current to increase the positive charge. All excited electrons bounce back down into the atoms = what we don't want. If there's a lot of heat above the excited electrons, that's the same as saying that there's a lot of free electrons above the excited electrons, which obviously opposes the upward jumping of excited electrons. We want them to jump to the moon, if possible, keep them off the atoms. So, by all means possible, remove those free-electron heat particles from above the sun-struck surface. It's not like they don't know it would help, and so I don't know why they don't use air currents to cool the surfaces.