Solar Update:
December 15, 2001
Well it's finally starting to get cold, and I now understand why:
There isn't much sunlight :-)
Despite the fact that all the leaves are off the trees, I am still getting 4 hours tops of sun on the panels. And the sun is definitely at a much lower point in the sky, meaning a much steeper angle to get to the panels. I can't crank the panels any further up than they are now, since if I do, I will only wind up shading panel two with panel one. As it is, panel two is about as far back as I can go.
Still, tilting the panels does make a significant difference. I was observing a short circuit amperage reading of 2.1 on the rear panel with 1.8 on the front (rear was inclined more than front) By bringing up the front panel, the numbers are now 2.2/2.2. Note that these are 120 watt panels *each* and the current is at about 30 volts (66 watts per panel) So I'm getting about 50% efficiency in the winter.
Not too great.
Still, I've put up a third panel. This is a little old SX20 panel I picked up on Ebay. It's already got a Zener diode and a blocking diode on the panel's box, in a nice weatherproof heat sink I'm mounting it on the roof to see if I can keep some 12 volt batteries charged over the winter.
So far though, I have been extremely satisfied with the operation of the shed. The APC UPS powers just about everything; the only thing that can overload it is the vacuum cleaner at high setting. Oh well. More interesting is the fact that running the vacuum on low (about 1,200 watts) brings the batteries down to their knees in about 10 minutes. As in 23.4 volts output under max load. The voltage isn't being lost in the wires; even at full draw the voltage drop is under .2 volts (1%).
I think the problem is the Gel cells can discharge a total of 80amps each, but not all at once. When I am pulling 1,200 watts, I am pulling 50 amps out of each battery. The batteries just might be unable to hold a 50 amp draw for any length of time while keeping the voltage up. Time to get some more batteries; I'm thinking along the lines of about 2-300 more amp/hours at 24 volts. That would keep me from wasting all that power I collect over the summer.
Can't wait for spring. Another week, and it will be the shortest day of the year. Then the days get longer, the sun gets higher, and more power arrives. Still, it looks like I was right, and that the system as designed has enough power to keep me running through the winter.
Chris