It All Starts With the Sun
There's a lot going on inside each panel, even though there are no moving parts. The light from the sun bombards the silicon semiconductors, or photovoltaic (PV) cells, with photons that knock electrons loose from their atoms to form an electrical circuit.
The flow of energy generates electricity, specifically direct current (DC). Each solar module is composed of several PV cells, and when multiple modules are strung together, the connections form the entire solar array. DC is converted to alternating current (AC) either at the panel through a micro-inverter or at an inverter mounted near the utility meter. AC energy is drawn into the house for consumption, or it's pushed out into the grid crediting kilowatt hours (kWh) of energy to you through net metering.
It's that simple. And it's a beautiful thing to see your meter spin backward. That is exactly what happens when your panels are producing more energy than you consume.
What is a kWh & Why is it Important?
Utility companies measure energy consumption in kilowatt hours (kWh). You'll notice on your monthly bill that you are charged according to the number of kilowatt hours used. This same utility bill also reports your annual usage. Your energy usage is a necessary measurement to adequately size your system to meet your requirements.
A kilowatt is a metric measurement, which is why most people scratch their head when they see the kWh abbreviation. A kilowatt equals 1000 watts of power. A kilowatt-hour is equivalent to the power provided over one hour. For example, if you have a 100-watt light bulb burning for 10 hours, you would use one kWh. A typical residence can consume anywhere from 5,000 to 50,000 kWh per year, depending on the energy sources use (gas, oil, or geothermal).