Solar Update:
October 7, 2001
Well, the system has been in for over a month now, and I still haven't depleted the batteries. Not bad since I am usually in there on the weekends, and have been popping in during the evenings off and on all month.
Today I used the jigsaw to cut the metal brackets for the panels. Until now they were held to the roof angle irons with 10 gauge wire and resting on an old UPS cover for inclination. Cutting with the jigsaw brought my inverter input current from 6 amps (with the lights and inverter on) to over 24 amps. 30 amps is the limit of the ProSolar power output, and 40 amps is the limit on my battery fuse. Thus if I start popping fuses, I will definitely need to think about wiring the APC UPS/inverter directly to the batteries. With really thick wire :-)
In other news, the LED lights are going strong. I have two clusters now, one cluster including 6 hi brightness LEDs and one with three. The one with six lights the work area quite nicely, while the three LED one is outside the shed lighting up the stairs. No more fumbling around in the dark, and both units are on 7*24. Which is possible because LEDs use SO DARN LITTLE CURRENT!!! At the current rate of drain (60ma) I will run the batteries down to zero if we happen to have oh... 55 days without sun...
The other light problem has been the inverter. When I was running 12 volts, the hot-wired APC 400VA UPS would use about .5 amps of power with no load. Not bad. The 600VA unit used a solid amp. Ok, 6 and 12 watts....
The APC 1200VA UPS uses *3* amps at 24 volts to keep itself running. Granted it has internal fans and a very heavy-duty rating, but 75 watts is a *lot* of power to waste when I am just running the 80 watt fluorescent lamps. In fact, that is almost a 50% loss of power in conversion.
A solution was needed :-) The goal of the solar shed should really be to run as much stuff on DC current as possible; running the inverter when needed. What to do? What to do?
Well, we went to IKEA, and sure enough, they were selling a set of halogen track lights (wires) for $25.00 a set. Closer inspection showed that they were three 12 volt halogen bulbs, the wire and turnbuckles, and a big honking transformer in what appeared to be an ostrich egg.
Hmmmm.....
Well, I bought two sets, and set one of them up tonight. The wire bus thing really looks nice on the rafters of the shed, and being that it's only 12 volts (fused at 5 amps) it's quite safe. I attached it to one of the batteries, put two 20watt lamps on the wire and checked the current.
3amps at 12 volts. 36 watts. Not too bad. And two bulbs were enough to light the entire shed nicely. Four should be enough to replace the old fluorescent shop-light, without the inverter or the power wasted in the ballast.
Next step tomorrow is to install the other light kit, and then wire them in series to the battery. Thus I will have a min of two lights running, four normally, and a max of six. Being in series, I can run the lights on the 24 volt battery output without any sort of resistors. And if I run four of them, I am pulling about 6 amps at 24 volts. So I can run the lights for about 10 hours before running the batteries down 80%. Run two and I would have a run time of 20 hours.
Not bad.
I might go to the solar shop tomorrow and buy another 120 watt panel. There is just this *need* to use all that sunlight falling on my other shed :-) And with 240 watts of power, I can think about expanding my battery capacity before the winter. I'm at 80 now, I'll be putting the two 24a/h batteries from the old UPS in soon (to 100a/h) and I think another 100a/h would be enough to run things for a good couple of days with complete recharge time still being under a week of sun...