One of the gals at work seems serious about moving off-grid, so while giving her the basics ( this one’s for you, P.B. ) I figured I’d go ahead and also get credit for an article. You can do this the easy way, or the efficient way. Easy is a panel(s) to a charge controller to a battery with an inverter hooked up to the battery. I would only recommend mono-crystalline panels. And I would recommend you buy them NOW before the prices jack up. I like buying multiples of smaller watt panels in case one fails, but you do get a better price per watt on singular larger rated panel. Right now at Amazon a 30 watt is $100 ( we’ll talk about how much you need shortly ). The panels come with no mounting hardware but with their own five feet or so of wires. To mount, I straightened out a couple of L brackets about two inches to a side- they hammer out as they are soft metal. Use #6 bolts to fit the pre-drilled holes on the panel. I put mine on wood pallets. The wires run to the charge controller ( which is rated usually at 100 watts max so don’t hook up too many panels to it, just get another controller for more panels ). Now hook up the controller to the battery. Use a marine battery, not a car battery. They only cost 20% more.
Look at the cold amp rating on the battery. A good rule of thumb is that these are the number of watts you can use before the battery is half discharged ( try not to go below that if you can help it, to prolong its life ). A 800 amp battery will give you 800 watts before it uses too much juice from the battery. Keep the battery outside because of poisonous gases it gives off charging, and try to keep it out of the cold. A box buried to its lid and an insulated lid is best if you get cold weather. Freezing the battery shortens its life. Now, hooking up all these is simple. You have positive and negative wires. Keep those straight and all will be well. The simple way is to hook up the inverter ( about $40 Wal-Mart. The new ones are nice as the fan won’t kick in til about 60 watts is drawn ). Panels use about 10% of their rated watts charging, and you will use another 10% using an inverter. Hence, a 30 watt panel under perfect conditions ( rarely achieved ) delivers 27 watts of storage to the battery and you end up with 24 watts after it goes through the inverter. I usually just subtract a third to get at the power generated and ignore the inverter “cost”. So every 30 watt panel is only giving me 20 watts ( all usage, generation is per hour ) power when the sun is out. With this inverter, you don’t have to buy any 12v appliances. You will easily find LED bulbs that go in conventional bulb lamps. Ignore florescent- go white LED. And if you buy a small flat screen TV it shouldn’t use too much juice. Use a laptop rather than a desktop to minimize power use.
What you need to do is add up all the hours the lights are on, all the TV use, any computer use- and arrive at a daily watt use ( calculate winter hour lighting use- not summer ) total. My advice is to assume one day out of the week you get eight hours of sun and the other days are cloudy and don’t use more than one of those hours for a total day ( you will still generate some watts even in clouds- but assume you don’t to be safe. I had to live on candles for a month when I first started because I had too few panels- it REALLY sucked. Soul sapping. Irritating. Depressing in actual fact. Don’t run out of battery juice ). Example- I use 50 watts a day total ( 5 watts an hour times five hours for lights and two hours of TV at 25 watts for 50 total ). In six days I use 300 watts. I have 75 watts of panels so in one day that will generate about 400 watts ( remember that one third loss from the officially rated wattage )-more than I need. Now, my usage is for 12v DC, not 110 AC. I don’t use an inverter for my regular appliances ( just occasional use ones such as hair clippers ). I have 12v bulbs and its holders and I use a 12v truckers TV. 12v is just like what you use in your car, primarily the cigarette socket and its mated plugs. And it is much more efficient than AC. You just need to buy more expensive appliances. That is about all there is to 12v power.
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