I built a small solar electric system in July 2000 (phase I overview below or technical details). It uses a solar panel to charge a small, portable battery. This $400 system is limited (by its battery) to 25 kilowatt hours per year. (The same money could have bought a less portable battery with larger capacity, increasing the yearly production.)
I expanded it in September 2000 to not only charge the battery but feed electricity directly into my home, 100 watts at a time (phase II overview below or technical details on a different page). This is called a utility intertie system. This $600-$750 system can generate about 154 kilowatt hours per year, (preventing the emission of 230 lbs of carbon dioxide a year, (a ton over ten years), 1.2 lbs of nitrogen oxides a year, and 3 lbs of sulfur dioxide a year). 154 kilowatt hours -- how much energy is that? It is about the same as using a personal computer with a big color monitor two hours a day all year long. Or one-third of what my refrigerator consumes.
I want to expand it during 2001, (phase III overview below or technical details), to feed about 1000 watts into my house circuits at a time. I expect Maryland state income tax credits and a Maryland Energy Administration grant to pay 50% of the total cost (which is between $8,000 - $10,000 with labor). Such a system would generate between 1500 and 2000 kilowatt hours per year, (preventing the emission of 3000 lbs of carbon dioxide a year, (15 tons over ten years), 16 lbs of nitrogen oxides a year, and 40 lbs of sulfur dioxide a year). Two thousand kWhrs would be 30% of our total yearly power use.
This small system gathers enough energy each summer day to recharge my Apple laptop computer, two cell phones, and my electric lawn mower (Black and Decker 5 horsepower, purchased at Home Depot). I use the laptop every day and the lawn mower once every week and a half during high-growth periods and once every two weeks in the middle of the summer. I have had enough extra energy (at least in August) to run a table lamp (compact fluorescent bulb, 15 watts) in the family room for a few hours on most nights.
You can build the same system for about $400. It generates about 500 watt-hours a week in the summer (half of a kilowatt-hour). Two of the three components of the system will not wear out for many (20+) years. Only the battery will need to be replaced every two or three years. The following picture includes four components. (In my case the battery and the charge controller were packaged together as one unit for convenience.)
For my next expansion step, I decided to skip the battery entirely. I used an "intelligent" utility intertie DC-to-AC inverter to pump electricity directly into my home circuits. This reduces the amount of power which is purchased from the utility company. It is also more efficient at capturing sunlight because
The inverter I chose to start with can create 100 watts of AC power at a time. It is easy to connect, safe to work with, weatherproof, and designed to last as long as the panel to which you connect it.
