How does a Solar PV (Photovoltaic) System work?
First, Solar panels installed on the roof or elsewhere convert sunlight into electricity. How?
Typically, you’ll need a south-facing roof not shaded by trees or other obstructions. We have a device (called a Solar Pathfinder) that can tell if shade is present on your roof at any time of the year.
This power from the solar panels, generated as Direct Current, is sent to an inverter.
An inverter has several jobs.
1 – It converts the Direct Current from the solar panels into Alternating Current, which your household appliances use.
(Some systems, such as ‘off-grid’ systems in houses that are too remote for the utility to reach, do not need an inverter because all their devices run on direct current). RVs and boats often have direct current devices, too.
2 – It matches the alternating current to the alternating current (AC) from the utility grid. Inverters must meet exacting standards to be approved for use. The California Energy Commission manages a list of approved inverters here: http://www.consumerenergycenter.org/cgi-bin/eligible_inverters.cgi
3 -The Inverter sends the electricity to the main circuit breaker panel in the house. From there, the electricity can go into the house to run appliances; if more electricity is generated than is used, it will return to the utility grid. If permitted by local Net-Metering laws, this will spin your electrical meter backward… effectively selling power back to the utility.
4 – The inverter ‘watches’ the utility grid so that it can shut down immediately if the utility grid shuts down. This way, if a storm or accident breaks an overhead electrical wire, your solar system will not send power into the electrical system and endanger people. Photovoltaic PV solar systems will only keep your lights on during a power failure if you have batteries attached.