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THE COMPONENTS OF A GRID TIED PV SYSTEM

A PV System includes:

1. PV ARRAY

Multiple PV panels installed together are called a PV array. Mounting arrays to rooftops is most common, yet they can also be located on a pole, a ground mounted rack, parking area shade covers, window awnings, etc. The PV array produces Direct Current (DC) power.

2. DC DISCONNECT

The DC Disconnect is a safety device that, when manually opened, stops power running from the array to the rest of the system. The DC disconnect is used during system installation and anytime your contractor needs to work on the system.

3. DC/AC INVERTER

The PV array produces DC electricity, however, we use Alternating Current (AC) electricity in our buildings and power grid. The Inverter converts the DC power to AC power.

4. AC DISCONNECT

The AC Disconnect is another safety device and is often incorporated into the Inverter. Seattle City Light does not require an AC Disconnect on most small residential systems. (For details on this exemption, contact your Electric Service Representative.

PRODUCTION METER

The Production Meter measures the energy output (in kilowatt-hours, kWh) from your system and is used to record the amount of electricity generated. This component is not critical to power generation, but is necessary in order to take advantage of Washington State’s Production Incentive Program.

6. BUILDING BREAKER BOX AND STANDARD UTILITY METER

Also called your building’s circuit panel or electrical service panel, the Breaker Box is where the power from the PV System enters the building. If the building is using electricity, the PV-produced electricity will be used first. If the building needs more electricity than the PV System is producing, utility grid power is automatically pulled into the building. When the PV System produces more electricity than is needed, the excess flows back out to the utility, spinning your utility billing meter backwards in the process. You earn credit for the excess power produced and can use that credit when the system is not producing energy. This process is referred to as “net metering.”


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