Net metering lets rooftop solar owners sell excess electricity back to the grid. When panels produce more than the home uses, the meter runs backward. The homeowner receives a credit on their bill. At night or on cloudy days, they draw from the grid and use the credit.

The policy has been crucial for solar adoption. It simplifies the economics. Instead of buying batteries, homeowners use the grid as storage. More than 40 US states have some form of net metering, though rules vary. Some credit at the full retail rate. Others pay a lower wholesale rate.

Utilities have pushed back. They argue that net metering shifts costs to non-solar customers. Solar owners use the grid but pay less toward its upkeep. The debate has led to reforms. Some states now use net billing, which pays a lower rate for exports, or time-of-use rates that value solar at midday less. The policy is evolving as solar grows.

Key issues

• Retail vs. wholesale credit rate
• Cost-shifting concerns
• Time-of-use pricing
• System size limits
• Battery pairing