Net metering is a policy for electricity aimed at consumers with RES facilities and allows them to use their energy whenever they need it and not only whenever they produce it.
"Net" in this sentence is meant as "what remains after offsetting" and in this particular case is to offset the energy consumed to the energy produced. For example if someone produces 100kWh in one day, these kWh go to the network and can be used at any time. Essentially we use the network as a giant battery.
In order for this policy to work, some rules should be established. Such rules are, for how long can the consumer keep this energy credit, how much will this credit cost or if there will be a connection fee or a fee for the use of this service etc. In contrast to the FIT (feed in tarif) policy currently in use in our country, net metering can be implemented as a single accounting offset without any other procedure.