The major components of a solar PV system are:
Solar Photovoltaic Array- The solar photovoltaic (PV) modules produce DC electric power by converting sunlight into electrical current. The process begins when the photons from sunlight strike the photovoltaic cells in each solar module. The cells are made of purified mono- or poly-crystalline silicon wafers and have layers doped with phosphorous or boron to create negatively charged (n-type) or positively charged (p-type) layers. The photons excite the electrons in the negatively charged layer causing them to flow to the positively charged layer and creating an electrical current. This current flows through wires attached to each side of the silicon, through all the PV cells wired together and out of the solar module.
DC Combiner Boxes- For larger PV systems, combiner boxes are used to consolidate the wiring from multiple solar PV module strings. This is used to help reduce the number of terminations and to properly balance the strings before they connect into the inverter.
DC Disconnect Switch- The disconnect switch is primarily a safety device to enable the inverter assembly to be electrically isolated in the event it requires servicing.
DC/AC Inverter Assembly- The inverter converts the direct current (DC) produced by the solar PV modules into alternating current (AC) so it can be connected into the customer's main AC power service panel. The inverter assembly may also be used as a voltage transformer depending on the system design.
AC Disconnect Switch- A safety disconnect on the AC power side of the inverter to allow for electrical isolation. This switch isolates the solar system from the utility grid and customer electrical system.
PV System Back-feed Breaker- The power from the solar PV array is interconnected into the main AC service panel just downstream of the utility company electric meter typically via a PV System Back-feed crcuit breaker. If this is not code compliant or cost prohibitive, the interconnection may alternatively be made with a line-side tap between the utility electric meter and the facility main disconnect switch. The electric meter usually has to be changed out by the utility company to be able to "spin backwards" and record when power is being sent back to the grid.
Performance Monitoring System (PMS)- The solar system PMS continuously monitors the system for faults and measures the amount of renewable energy being generated by the solar system. The PMS must be certified by the CA Energy Commission as it provides the output data directly to the utility company which is then used as the basis for the rebate payments back to the customer. The PMS display can be viewed at anytime via a portal on the internet and can have an optional lobby display or kiosk if desired.