OK, I thought I would do a quick post on our initial days with both solar and wind generation. A some of you can probably imagine I can become pretty obsessed with the data from our production (what the heck else do I have to do).
So first the data from our solar arrays. We have 3 300W solar banks running with MPPT controllers. Over the year of watching the data, each one of those banks produces about 9A on average for 8 hours a day. That works out to about 72 amp hours a day. The quick maths people are now going whoa, that’s under 1/2 their rated power. Yes it sure is. There are a couple of reasons for that.
1. Shades and cloud. When our panels are shaded or it’s a cloudy day our production is massively reduced (sometimes to zero).
2. Flat install. Solar panels are rated at the optimal angle. For a flat install we take between a %15-20 loss depending on the time of day!
3. Batteries. We have more solar than our lead acid batteries can actually take. The resistance in our batteries limits the current that can flow into the batteries.
Next, Wind generation. Of course we don’t have anywhere near the data on wind that we have on solar. However we have gathered some data in the last few weeks of light wind. We average about 2.5A of output for 24 hours if I remove the windless days. That’s 60 amp hours a day. I think its only fair to remove the completely windless days as they are an anomaly here (seriously there were days our anemometer didn’t even register 1knot). We just happened to put up our wind generator in a weather anomaly, but time will really tell.
Alright so what can we glean from this data. The first thing I take from this is that the myth of wind being useless (at least here in the Caribbean) is debunked. Even in this light wind, the wind generator almost kept up with a 300 watt solar bank. The fact that a wind generator will produce power 16 more hours a day is HUGE. Of course this leads to the next question. How do you stand listening to it at night? I will admit that we had a few very rough nights as we were not used to the sound. We have now become mostly accustomed to the sound and I barely notice it anymore. It sure is nice to wake up with the batteries barely drawn down.
What would I have done different in hindsight. First I would have probably put in different batteries. I should have spent the money on Carbon Foam AGMs (I still think Lithium is not mature enough). Second I should have put up one less solar bank and put the wind generator up much earlier. These changes would have allowed a more smooth battery charge curve. We would have had a more constant charge through the day and not struggled through the night. As it stands, our batteries are stuffed by about 11:00am and we are trying desperately to pull the extra power into something. We go crazy charging the laptop batteries, power banks and tablets. With the wind generator, I no longer have to get up at night and check the voltage or turn off the freezer.