Solar Electric

Solar electric systems use a chemical reaction to sunlight to generate electricity. The panels that are used to create the electricity are called photovoltaic modules. The installations are commonly called PV systems. PV systems generate electricity during the day only and usually are generating their highest amount of electricity in the afternoon. PV systems do not generate electricity at night, even under a full moon. When it is cloudy, rainy, or if the modules are dirty the PV system will generate less energy.

As of 2008, there are nearly 40,000 PV systems installed all over California at homes and businesses. Builders are also installing them in new homes.

The majority of the systems installed in California are connected to the local utility. This is called a grid-connected system. The systems do not have any batteries and will not operate when there is a power outage. When the PV system does not generate enough electricity to power the home or business (for example, at night) the local utility provides power to the site. When the PV system generates more electricity than the site can use, the excess electricity flows back in to the grid. All of this is done automatically.

When you have a PV system installed you will have a choice about your electric rates. Electric rates are charged based on something called a rate schedule. The local utility publishes their rate schedules on their website. Some customers are on a rate schedule called ‘baseline’ and others are on ‘time of use rates’ (there are many rate schedules - this is a simplified description). Baseline rates charge customers for electricity based on the total amount of electricity used each month. Time of use rate charge customers for electricity based on the amount of electricity used at a given time period. Since the highest demand for electricity is usually in the afternoon, time of use rates are higher during those period of high energy demand.

The rate schedule choice is important because all customers are eligible for a program called ‘net metering.’ Net metering gives customers who generate excess electricity a retail credit against their utility’s energy bill. When the customer is using energy, the utility applies these credits against the bill. The net metering credits are balanced annually. Some utilities will allow credits to roll over to the next year and others do not.  At the beginning of each year, the net metering account starts over again. Time of use rates can work well with net metering, particularly if the PV system produces excess electricity during peak periods - the time of day when the highest rates are charged for electricity (net metering customers who produce excess electricity during those periods will receive the highest credits). However, if a customer would like a state rebate, PV companies may not install systems larger than on-site demand, so customers should not try to install a system that is larger than what they need for their own use.

Some people would like to sell their excess electricity to the utility. When a PV system generates excess electricity, customers do not get paid for this electricity. They receive a retail credit to their energy bill. If a customer sold electricity to the utility it would more than likely be at a wholesale rate that is lower than the retail credit they receive through net metering. Someday this may be a practical choice but for now it is economically better to install a system that is sized to meet on-site load.

The State of California authorized a rebate program that is called the California Solar Initiative. These rebates offset roughly 20% of the cost of the installation. Your local, reputable solar contractor can advise you on how to claim these rebates. Most companies will do the rebate paperwork for you.