Small Steps Into Renewable Energy: Page 2 of 4

Intermediate

Inside this Article

Stephen and his array
The author with his power system in heavily wooded, sun-scarce coastal Oregon.
Balance of system
The power wall nears completion.
System batteries
Eight Xantrex 1200-200 sealed, absorbed glass mat batteries­—400 amp-hours (20 KWH) at 48 volts DC.
Stephen and his array
Balance of system
System batteries

The generator consumes about 1/4 gallon (1 l) of diesel an hour at idle and about 9/10 gallon (3.4 l) at high output. I use jerry cans for fuel storage, and a single 5-gallon (19 l) can often lasts for weeks. I rarely run the generator more than half an hour each day. I use off-road diesel, which is not taxed for highways in Oregon. This saves some cash. I have not even spent US$50 on diesel this year.

I chose a 240 V generator because I have some equipment that uses 240. I have a 120-volt inverter that is connected to my battery bank and to one 120-volt leg of the 240 VAC generator output. So while the generator is running, I have 240-volt electricity from the generator to power shop tools, and 120-volt electricity to charge the battery bank via the inverter.

I quickly found that a short stint of generator charging while doing carpentry work keeps the system fully charged. As you gain experience charging various battery systems, it becomes clear that the charge rate a battery bank will accept drops rapidly as the bank reaches full charge. I usually turn off the generator as the charge rate falls below about one-third its highest rate. This leaves the topping off for the sun or wind. It also restores silence for the birds, bees, and bears. And it quiets those who insist my place is really a beached diesel submarine.

Power Center

After careful study and listening to good advice, I decided to make a standard AC household. It is clearly possible to design a fully DC system, but DC appliances are more expensive and offer a very minimal product line compared to their AC counterparts. I remain very pleased that I chose standard 120 VAC service for the output side of my battery system. Everything on the “living” side is “normal.” I chose 48 volts DC as my nominal charging and battery bank voltage. This allows for longer distances between the batteries and RE charging sources, smaller gauge and less expensive wires, and fewer parallel wiring connections.

I was quite lucky to purchase eight discontinued Xantrex (formerly Trace) 12-volt, 200-amp-hour (2.5 KWH) sealed, absorbed glass mat batteries at a significant discount. This yields a total of 400 amp-hours of battery capacity at 48 volts (20 KWH; 10 KWH at 50 percent depth of discharge).

I purchased a reconditioned Xantrex 5548 inverter. This inverter produces reliable AC electricity, manages battery charging while the generator is on, and allows for remote or automated generator start-up and shutdown.

I played with all the automated functions for several days. I even set up the system to start the generator whenever I drag the system down with a lot of use of my 13-amp, worm-drive skill saw. But now I never use the automated functions. I do use the menus to remotely start the generator for either charging or 240-volt electricity, but see no need for further automated complication. I don’t really want the generator starting up while I am away.

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