How Solar Electricity Moves Through Your System
The Solar Array
One of the great things about solar power is that there are no moving parts in a PV array. The solar cells (usually made of silicon) sit in the sun. When a photon from the sun hits a cell, it knocks loose an electron from the silicon atoms that make up the cell. There are wires connected to the solar cell that collect these roaming electrons. The wires are connected to other cells and all of the cells together make a solar panel. One panel is connected in the next in a combination of series and parallel connections known as a “string.” All of these connections of cells, panels, and strings are considered a solar PV array.
The Solar Inverter
These connections attach to wiring that comes down from the roof in one or more conduits. The conduit delivers the wire to an inverter. The inverter is usually located near your Main Service Panel in a garage or on an exterior wall. The inverter converts the DC electricity of the solar array to AC electricity that is used in your house. In most cases it also has an LCD display that allows you to read data about how your system is performing at the moment and over time.
From the inverter, AC electricity travels through additional wiring and conduit to a Production Meter and maybe even a utility required AC Disconnect. The Production Meter is there to measure all of the solar power your system produces before it’s consumed by loads in the house or traded with the utility. This is an important step because Washington State’s Production Incentive is paid based on the data recorded by this meter.
The Main Service Panel
From the Production Meter the electricity flows through more wiring and conduit to your Main Service Panel. We are required to land the solar breaker on the opposite end of your panel from the main breaker by the NEC. Depending on your system design and the state and age of your service panel, we can also connect using a Line-side Tap. The main components of your system that we install end there at the breaker. But the solar electricity flows first to any loads running in the house, mean you are using solar power to run any electrical appliances in the house!
The Net Meter
The solar electricity keeps flowing though. If you only have a few loads consuming your solar power, and there is excess power being produced the electricity is pushed out to the world at large through your Net Meter. A Net Meter is also considered your "Utility Billing Meter." Here in Washington State, your utility allows you to spin your Net Meter backwards and generate a credit for your excess solar power on your bill.
Probably the only other component you might want to consider adding to your array (but isn’t necessary) is data monitoring. Monitoring collects data from the inverter, and can display it locally on something similar to a wall hung thermostat or could be web-based that would allow you (and us) to monitor your system remotely.
And Voilà, your home generates it's own solar power!
Solar System Components
- PV Array – A collection of solar panels usually mounted flush to your roof.
- Inverter – (central string inverter shown) converts the DC electricity of the solar panels to AC electricity used by your house.
- Production Meter – Measures all of the output of your system before it is used in the house. This is required to participate in Washington’s Production Incentive.
- Main Service Panel – The solar output is usually placed on a breaker in your electrical panel. The solar electricity is used by the loads in your house first, and excess is pushed back out to the grid.
- Net Meter – Your existing billing meter with the utility. It measures the net power consumed and produced by your house.
- Utility Grid – The infrastructure the utility has in place to deliver power to you when you need it, and to accept the excess solar power you produce.