One fact that often surprises people is that the most commonly installed residential solar energy systems do not have batteries. These “on-grid” or “grid-tied” systems are connected to the home’s electrical service, and feed any excess power being produced, beyond what the house is consuming at the moment, back into the grid.
This back-fed power will literally run the meter backwards, providing the home with a credit to be used when the system is not producing energy (such as at night).
No battery is required because grid power is always available to make up for any electrical needs not being supplied by the solar system, such as on cloudy days, and of course at night. This is sometimes referred to as “using the grid as the battery”.
Off-grid systems, which are not connected to the power grid, do require batteries to store energy for use when the system is not producing, such as at night.
