HOW THE SOLAR ELECTRIC SYSTEM OPERATES

A photovoltaic (solar electric) system literally means photo, “produced by light” voltaic, “electricity produced by a chemical reaction.” With a solar electric system you get 100% clean electricity from the sun. A system consists of five to six major parts that allow you to harness the power of the sun and in essence become your own power company.

The Sun as Source

Light rays from the sun - those that you can see (visible light) and some that you can't see (ultra-violet) - produce electricity in the panels. The sunlight's interaction with certain materials, such as silicon in the PV module, frees electrons which are collected to form direct current (DC) electricity. DC electricity is converted by an inverter to AC power for your use. PV systems produce power intermittently because they work only when the sun is shining. More electricity is produced on a clear, sunny day and with a more direct light angle, as when the sun is perpendicular to PV modules. Cloudy days will reduce output and no power is produced at night. PV systems work best during summer months when the sun is higher in the sky and the days are longer.

Solar Panels and Mounting Structures

The photovoltaic panels themselves are the power producing mechanism. They are assembled from solar cells. Each cell produces electric power when exposed to sunlight. The manufacture of these cells is a highly technical process similar to that used to make computer chips. The frame or mounting structure consists of aluminum and stainless steel units which are used to attach the system to the roof of your home, business or freestanding structure.

The Inverter

The inverter converts DC (direct current) power to AC (alternating current) power, like your local power company delivers. This power is used to run the electrical loads in your house. Any extra power will be sent back to the utility for a credit (see the California Net Metering Bill section). The inverter is enclosed in an attractive cabinet that can be mounted inside the home or garage, or on an outside wall.

Electrical Panel and Circuit Breaker

The power output from the inverter is usually connected to your home at the main electrical panel (next to your utility meter). A dedicated circuit breaker will be installed for the PV system. If you choose the battery backup option, to give you power during a utility outage, a new electrical panel will be installed for essential household circuits. The existing electrical panel retains non-essential household circuits that do not require power during an outage.

Batteries (Optional Feature)

Batteries can be included in the system to provide backup power in case of utility power outages. During a power outage the inverter produces AC power from the batteries. The solar panels recharge the batteries during the day. If you are looking for a reliable generation system that can function independently of the utility grid, batteries may be a viable component for your system. When making this decision, please be advised that battery systems are not eligible for state rebates unless they are grid connected.

System Location and Size

The best orientation for a PV system is on a south to southwest facing roof; however, roofs that face east or west may also be acceptable. Flat roofs also work well and tilting them up to 30 degrees towards south will maximize your rebate incentive. If a rooftop cannot be used, your PV array can also be installed on a ground anchored rack or trellis.

As a general guideline, each kilowatt of photovoltaics requires about 100 square feet of unobstructed space. To begin, first determine how much electricity you use; and then consider what percentage of your electricity needs the PV system should supply.