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Questions & Answers

Do your arrays take care of all of your electricity (TV's, computers, appliances included) or is it just good for lights?
We have a grid intertie with battery back up system. In the month of May, we produced 100 kWh more than we used (about 17 days worth of power for us). That's with quite a few days of cloudy weather. We make way more electricity during the day when the sun is out than we use and the electric meter moves backwards. Then at night, we use electricity off the grid and the meter moves forwards. During the sunniest months of the year we will produce more than we use and during the cloudy months of the year with shorter days we will use more than we produce. As far as can figure though, we will still come out quite a bit ahead over the next 12 months. We sized our system to cover all of our electrical needs. However, when we use the electric stove, oven, or hair dryer, even during a sunny day, the meter moves forwards. You can size a system to just cover part of your needs and add on over time too.

Does it heat the house?
No, it does not heat the house, at least not directly. We heat our house with a super efficient wood pellet burning stove. It uses some electricty (less than 200 watts an hour) for lighting the pellets and for blowers to distribute the heat into our home.

Can you go off the grid?
Yes, if we wanted to go off the grid, we could. We would have to invest in more batteries to store about a weeks worth of power, though, and right now our battery bank stores about a day's worth of power. The other obstacle is that when the meter spins backwards as we're putting electricity into the grid, we get credit for that exact amount of electricity to use later that day or in the winter. Battery banks are not as efficient, as there is energy lost over time through storing it. Our system is designed to provide us with power during a blackout. During the day we would run off of the solar power more or less directly. At night we would run off of the batteries. We have set aside certain circuits that will be on during a power outage. These circuits allow us to run the fridge, microwave, cordless phone/answering machine, entertainment center, water heater, computers and lights upstairs, some lights in the dinning area, family room lights, and bedroom lights. We can not run the dishwasher, washer/dryer, garage beer fridge, and some lights during a power outage.

Can you sell your energy back to PG&E?
We signed up for PG&E's "Net Metering" program. This means that we get credit for power that we produce over a twelve month period. At the end of that period, if we produced more than we used, we owe them nothing. If we used more than we produced, than we owe them the difference. As it stands right now, PG&E does not literally send you a check for the power that you produce in excess of what you use. In some states this is the case. The Wisconsin utility send people checks every month. I wish that's the way it was here, but it's up to PG&E for now. Actually PG&E still charges us about $4.50 per month for the use of their electric lines. I don't think this is fair (we're producing clean energy when they most need it), but they only worry about the bottom line.

Would it be enough to charge an electric car?
Of course it is possible to have enough photovoltaics to charge an electric car. But it is possible to charge your electric car without actually producing all of the electricity you need to charge it and still pay nothing for it. That's because electric car owners have "Time of Use" agreements with PG&E. For example, during the day when PG&E needs the electricity most, your solar panels are producing it at a sell rate of about $.30 a kWh. At night when you charge your car, you're buying back the electricity at around $.06 a kWh.

How much was your last PG&E Bill?
Our total PG&E bills for 2005 were less than $200.
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