I’ve talked about planning and calculating solar equipment/batteries before: here and here. Read these first if you’re planning for solar. Now that we have made all our decisions and are living daily with result, I have a few thoughts on the whole calculation business. These thoughts are affected by the realization that you really have to get a generator and that ours will turn on and off automatically as needed.
Why do you need a generator? No matter how well you plan, something could go wrong. A couple of my neighbors discovered this recently when one lightning strike took out both their inverters. If you agree about needing a generator, calculating what you need in the way of solar power should take this into account.
1) You absolutely need enough battery power to last 24 hours. (In three months we have never failed to charge the batteries each day.) I don’t know where they came up with get enough batteries to last three days. It’s nice, but batteries are very expensive.
2) The most important thing to calculate is the continuous average wattage you expect to use. Things that are rarely used like vacuum cleaners really don’t need to be calculated except for a maximum watts at one time calculation.
For us, this is about 450 watts. At night we often creep down to 200 or so watts; never under this. During the day it’s usually between 400 and 500 watts. If the refrigerator is working hard, it can go up to 800 watts or so for awhile.
3) You need to have an idea of the maximum watts you’ll ever expect to need at one time. Inverters are rated by the maximum number of watts they can deliver. Our inverter can deliver 6000 watts. I doubt we’ve ever used 3000 watts at one time. We for sure have used 2000 watts.
4) Plan your system so you don’t go broke running your generator, but also plan your system so you don’t go broke trying to live without a generator.
Other thoughts on solar power-
No one ever talks about this- (I realize it’s probably because it’s a bad idea, nonetheless…) I increasingly feel that a few panels facing east and west would be of value. For us I think 600 watts each direction would be pretty useful. Basically it would extend the number of hours a day you produce power–you start generating power earlier in the day and later into the evening.
I’ve thought a lot about wind energy and I’ve given up on the idea. We have great wind quite often; however, it’s not reliable enough that you could count on it. If you can’t count on it, then you need another plan.