You need to take time and figure out what electrical
devices you use, how long you use each device on an average day, and how much energy each device uses. This tells you how much energy you need to produce every day (average) in order to be self sufficient.
Then decide how long you want to be able to go without charging the batteries. Most people want to be able to last at least a couple of days, some want more like 4 or 5. Let's say that you use 80 amp-hours per day, at 12 volts, and you want to be able to go three days without charging. You need a battery
bank that holds 240 amp-hours, right? WRONG! You cannot draw 100% of the energy from your batteries no matter how hard you try, and you cannot draw more than about 80% without permanently affecting them. You should not plan on routinely using more than 60% of the energy in your batteries, and it is better to budget
for using 50% or even 40% (if you really want your batteries to last a long time). That means that to be able to use 240 amp-hours over the course of three days without recharging, your battery
bank needs to be 400 amp-hours at a minimum, and 500 amp-hours would be better.
Next decision is what kind of generation devices you want to use--wind, solar, towed, diesel
generator, etc. While the idea of being able to generate all of your electricity from wind and solar is nice, you have to be prepared for the possibility of several days without sun or wind. What will you do then? If you have an alternator
on your auxiliary diesel
then you are probably covered. If not, you either need to find another way of charging batteries, or you need to have a REALLY BIG battery bank!
You've decided how big your batteries need to be and how much energy you need to generate, the next thing is picking the devices to generate that energy. If you live in an area with constant, steady winds above 10 knots then a wind generator should work very well. They come in different sizes and generate different amounts of energy. Some make more noise
than others. Some are notorious for making a LOT of noise! Do some research
and pick the one that best fits your needs.
Live someplace where the sun shines bright nearly every day? Then solar is a good choice. Again, different panels
, different sizes, different costs, different energy production. One key with solar panels
is where to mount them. Even a little bit of shadow across a panel will seriously degrade the amount of electricity it produces, so try to find someplace that is in full sunshine.
Most places a combination is a good choice. Here in Florida
, for instance, if the sun is not shining then the wind is probably blowing. The sun shines most of the time, though, so if I were putting together a system I would plan on solar panels
for most of my energy and a small (preferably very quiet!) wind generator to help out on those few cloudy days.
Hope this helps to get you going in the right direction. The main thing to realize is that you simply CANNOT just buy any old wind-generator, or solar panel, and think that you are now good to go. You MUST look at this as a total system design involving all of the elements of use, storage, and generation. Yes, it takes a lot of time, effort, and research
to do this right, but the alternative is wasting money
on bits and pieces that do not work together and do not serve your needs.