Advocates for renewable energy hail net-metering as a key policy so that electricity from solar and wind is generated at the same place where it is consumed.

Supporters refer to it as the policy that lets the electric meter spin backwards. It allows people who own solar power systems, for example, export electricity to the grid and earn credits — at retail prices — on their utility bill.

In a new report called “Freeing the Grid,” advocates with several groups grade each state on their net-metering policies.

Environmental trendsetter California tied for fifth, but Colorado got the top spot.

Delaware, Maryland and New Jersey followed Colorado in the ranking, while California, Oregon and Pennsylvania tied for fifth.