Net energy metering (also referred to as NEM) is a billing mechanism, which allows a customer to store the electric energy in the electric grid operated and controlled by the electricity supplier. This stored energy originates from a consumer’s ability to generate energy by the means of renewable energy sources solar and wind. Then, the NEM lets the particular household benefit from the fact that some of their energy was not used at the time of its production and sent to the grid’s infrastructure instead.
To check how it works in the case of solar energy, see the article below:
What is net metering in solar energy?