We’re into the part of the year that is hardest for those living off grid, when the days are getting increasingly short, the sun doesn’t appear that often, and when he does, he’s pretty low in the sky. Having been terribly casual about the whole energy thing all summer, once the autumn equinox has passed, we need to shape up and tighten our belts a bit. This includes making sure we can harvest every last bit of daylight and wind.
Our old 80w BP solar array, which is at about 60 degrees
We’ve already taken care of some of the wind by raising the turbine up some, so now its been the turn of the solar. There are 2 big arrays here, one of the old BP solar panels that is quite upright – its about 3.2kW. The other one is the new array of 3.9kW that is in the plastic buckets on the ground, and was at an angle of 15 degrees.
There’s a bit of a debate about whether angling panels up really makes a difference, or whether just pointing them at the sky means you’ll get a lot of diffuse reflected light. Well, I noticed this week that on a cloudless, sunny morning, I was getting almost exactly twice the output from my old array at 60-ish degrees than the new one at 15 degrees. Thats a lot at this time of year.
The solutions included propping the buckets up on earth banks, or making a new fixed rack for the panels, both of which involved lots of digging or money, or both. In the end the solution was 20 quids worth of steel bar and bolts, and I just jacked up the back of the panels to about 45 degrees. A couple of hours later, the output of both arrays was equal. I moved the panels into a slight arc so that they get sun earlier in the day, too, and the cats can’t sleep on them either. Now I’m confident that we’re getting as much as we can out of them as we can, certainly until I can build a fixed rack to get them up off the ground.
