Solar powered car

Most people will tell you that you can’t run your car on solar electricity, but that’s exactly what I do. In 2001, during California’s energy crisis, I installed a grid-tied solar-electric system with design assistance from Bob-O Schultze of Electron Connection. My original motivation was the desire to avoid rolling blackouts. Today, not only am I powering my home with solar electricity, I’m running my car on sunshine too! Our system has 3,600 watts of solar-electric (photovoltaic; PV) modules mounted on three dual-axis tracking pole mounts.

At our location, the tracking arrays generate about 30 percent more energy than fixed arrays on an annual basis. Since the system is tied to the utility grid, there is always somewhere for our electricity to go, and regulation losses are avoided. To ensure that we have electricity during power outages, a deep-cycle battery bank was included in the system. The inverter maintains the batteries at 100 percent state of charge, so they’re always ready for the next utility outage. I have been extremely happy with my PV system, and delighted with the decision to include battery backup. While the grid goes down periodically, our home has never experienced any blackouts. When the grid fails, our inverter seamlessly switches our appliances over to the battery bank, and life continues normally. The system functions as a wholehouse uninterruptible power supply for all 120 VAC loads. Efficiency & Rates Before the installation, I reduced my monthly electricity use from about 1,000 KWH to around 600 by replacing a refrigerator and freezer with new energy efficient Kenmore appliances from Sears, and converting all the house lights to compact fluorescents.

I signed up for the then-new, E-7 time-of-use (TOU) net metering rate schedule from Pacific Gas and Electric (PG&E), which paid US$0.31 per KWH, the peak rate, for all electricity metered back to the grid for the six summer months, from noon to 6 PM, Monday through Friday. The off-peak rate was US$0.08 per KWH, and covered all the other times. This large differential in rates provided a strong incentive to shift electrical loads out of the peak period and into the off-peak period. With the help of several timers, my wife and I manage to use very little electricity during the peak period. As a result of the TOU rate schedule and our load shifting, at the end of the first twelve months we had a positive balance with PG&E of US$88. This is called the true-up period, and unfortunately our utility does not have to pay us this amount. On the other hand, the TOU schedule did allow us to use 1,840 KWH more from the grid than we generated that first year. By the middle of the second year, it became obvious that our surplus for the second twelve months was going to be almost two-and-a-half times the US$88 of the first year because of improvements in our load shifting and further conservation efforts. We started to talk about how to use up this surplus because there was very little appeal in handing more than US$200 to PG&E.

Electric Vehicle The obvious solution was to buy one of the Toyota RAV4 EVs that were available at that time (the end of 2002). I was dragging my feet, but my wife prodded me into action, and we traded in our Acura for this electric vehicle. If I had not followed my wife’s prodding, we would not have this car. Soon after placing our order, Toyota announced that they were discontinuing production of this vehicle and taking no further orders. We bought the car late in the year, so after the second twelve months we still had a US$112 surplus with PG&E and a 1,550 KWH positive energy balance. I was somewhat expecting this car to more than use up our surplus. But after the first full year’s use of the RAV4 EV, we still had a zero bill with PG&E, but had used 3,568 KWH more from the grid than we generated. We put about 12,000 miles (19,000 km) on the EV for the year, and it uses about 300 watt-hours per mile. All of these watt-hours were charged during off-peak times at US$0.08 per KWH. Without the solar-electric modules, if you had to pay US$0.08 per KWH to charge this car, it would cost less than US$0.03 per mile for the electricity, compared to the US$0.10 per mile (or more) you pay for a gasoline-fueled car. The car uses about 3,600 KWH per year, just about what our net usage from the grid is per year.

The fact that we owe nothing for electricity used by our house and car is entirely due to the E-7 TOU net metering, and really demonstrates the effectiveness of the combination of a solar-electric system with this rate schedule. Unfortunately, the gain available with this rate schedule is entirely dependent on the size of the summertime peak rate, and PG&E lowered it from US$0.31per KWH to US$0.29 per KWH. This may have the effect of pushing my current year’s bill into positive territory, which has given us incentives for further conservation. Petroleum Free After rebates and tax credits, the solar-electric system cost about US$26,000 and the car about US$29,000. I would have bought both without the rebates and tax credits, and never intend to go back to a gasoline car. The PR campaign by the automakers and the petroleum industry to turn the people of this country against EVs is a national disgrace and a big step backward for the sustainability of the planet.