How does a solar system produce electricity?

Light striking the solar modules contains energy in the form of photons. When the photons hit the module’s silicon solar cells, energy is transferred, freeing up electrons. These electrons move through the silicon to the nearest wires and create positive and negative charges. When the millions of electrons flow through the wires of the solar electric system, they create electric power. The more intense the light, the more electrons that are available and the larger the electric current produced.

The electricity from the solar array is in the form of Direct Current (DC), much like a high voltage battery. It is of no use in our houses, however, because our appliances operate on Alternating Current (AC). To make the electricity usage, the wires joining all the solar modules carry this DC electricity from the solar array to the Inverter. The Inverter transforms the DC into AC electricity and feeds that electricity into your home’s existing wiring, typically through a circuit breaker in an existing panel. The inverter is usually located in a basement, garage or outdoors.

The inverter is a sophisticated electronic device with its own operating software, and it monitors the output of the solar modules. It also monitors the voltage and frequency of the electricity coming from the utility, so that it’s electric output precisely matches the utility-supplied electricity. For safety reasons, if the utility power is interrupted, the inverter shuts down and waits for the utility power to be restored. Five minutes after grid electricity is restored, it resumes normal operation.

At times the solar array will produce more electricity than is presently being consumed. The extra electricity produced naturally flows out of the house and onto the utility wires. The outward flow registers on the utility meter by spinning it in reverse, giving the solar electric system owner full credit for the excess electricity they produce. If the solar array produces less, then additional electricity from the utility flows in to supply the balance needed (of course, this will always be the case at night).

In the event you produce more electricity in any month than you use, you can carry the credit forward. Most customers produce more than they use on sunny days, building up a credit to be used at night or on days of lower production.

NO MORE utility tiers from power companies!

Since residential rates are “tiered”-meaning the cost per kilowatt-hour (kwh) increases as you use more energy – your cost to run your household items depends on the overall amount of electricity you use.The basic charge for residential customers covers some non-energy costs associated with providing basic services such as bill preparation, meters, meter reading, and customer accounting. This charge ensures that each residential customer, regardless of monthly usage, contributes equitably to cover costs associated with providing basic electric services.

Standard Residential Rate

The Residential Plan is the basic rate for residential customers and features a 4-tiered structure. Tier 1, or your baseline allocation*, is the established amount of energy (kWh) you need for lighting, cooking, heating, and refrigeration. This baseline is established by the California Public Utilities Commission (CPUC) and is based on where you live, the season (winter or summer), and whether your home is “all-electric” or uses both electricity and gas. *Baseline electricity allowances are an established level of kilowatt-hours (kWh) provided to residential customers. Pursuant to State law, baseline allowances represent the electricity necessary to supply a significant portion (50-60%) of the reasonable needs of the average residential customer.

Additional Charges

Every residential bill includes some non-energy costs for providing basic services like bill preparation, meter reading and customer accounting. This charge ensures that every SCE customer contributes equitably to pay for these services. Each residence is also charged for other CPUC-approved services like power generation, transmission or distribution. This charge is based on the number of kWh used and may change monthly, based on power generation and water resources factors.

Understanding Tier 1 (Baseline)

The “baseline allocation” is an established amount of energy (kWh) allocated for basic services such as lighting, cooking, heating, and refrigeration usage. Residential customers’ baseline allocation is established by the California Public Utilities Commission (CPUC) to ensure that all customers can purchase a basic supply of energy at the lowest rate in effect. Your specific allocation depends upon your baseline region, the season (winter or summer), and whether your home’s source of energy is electricity only or a combination of electricity and gas.

Photovoltaic Solar

A customer investing in a solar PV system should understand the economic payback on his or her investment, even if there may be strong non-economic (e.g. environmental) factors driving the purchasing decision. The initial investment depends on the system size. A convenient factor that takes this into account is the price per peak Watt (Wp) of the system. Hence, a 2000-Watt peak (2kWp) solar energy system costing $16000 in total (i.e. including installation) will correspond to a price of $8/Wp. In some countries, you may be able to obtain a grant or rebate towards the cost of the system, which will obviously improve the economic payback on the purchase.