Think of your home as an electric meter working backwards. When averaged over the course of 12 months, if your solar or other renewable energy system generates the same amount of energy as your house consumes, the effect is known as “net zero.”
“Positive energy” is the result of your system producing more electricity than the house consumed. Positive energy is classified as “excess generation” on your monthly utility bill, and many people are using excess generation to power their electric vehicles.
Grid-tied renewable energy systems operate under a two-way connection that enables homeowners to always have power. As “site-generated” electricity is depleted, the electrical system seamlessly switches to grid-supplied power. Standalone renewable energy systems are known as “off-the-grid.”
Your monthly utility bill will separately itemize electricity that is site-generated vs. grid-supplied., along with dollar values. Companies typically offer “billing credits” toward your next month’s bill. However, depending upon local laws and your utility agreement, you might be able to sell your energy in the form of a Renewable Energy Certificate (REC) or a Solar Renewable Energy Certificate (SREC).
It’s all spelled out in Live in a Home that Pays You Back.