Bob's Links and Rants

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Sunday, September 05, 2004

Solar Mission Expanded!

Pictures of my new, expanded solar-energy system:

That's my new Evergreen 102-watt photovoltaic panel, soaking up the rays!
The orange wire from the panel connects to a "maximum power-point tracking" charge controller (not shown), which is then connected to the batteries. In this setup, I have four 12-volt batteries plus my Xantrex power pack, which contains three 12-volt batteries in parallel and an inverter, all being charged by the panel. I can then run 120-volt devices using either the Xantrex's inverter or the 300-watt Radio Shack inverter.

One way to make solar energy go farther is to use direct-current devices when possible, thereby skipping the use of an inverter, which lowers the efficiency. I bought the 12-volt car fan (below) at the local Kiwanis sale for $8--it moves an incredible amount of air, and can run for close to twenty hours on one of my batteries (although I try not to run them that long, since it shortens their life).

A friend at work suggested a great way to save money on a solar-electric system. Universal power supplies, or UPS's, are commonly used to protect computers from power outages. A UPS is basically a combination of a battery and an inverter. When the battery dies, most people get a new UPS. But the inverter probably still works, and it may well be a better inverter than my $100 Radio Shack model. The Radio Shack inverter has a maximum output of 300 watts, and delivers modified-sine-wave AC power. This is approximately, but not exactly, like the sine-wave AC delivered by the utility. Some AC devices don't run well on modified-sine-wave. UPS's, though, generally have "true" sine-wave inverters which deliver AC as good as or better than the utility. Even new UPS's aren't terribly expensive, and if you can get one being tossed for free, you've got an important part of a PV system without paying a dime!