How Do Utility Companies Measure Solar Energy Production?

Measuring Solar Energy Production

Utility companies use a device called an inverter to measure the output of a solar array in real-time. The inverter converts the DC power generated by the solar panels into AC power that can be fed into the grid. The AC power output is then measured using a device called a “gross meter” or “export meter,” which records the total amount of electricity exported to the grid.

Net Metering vs Gross Metering

In the United States, net metering is the most common method used to measure solar energy production. Net metering measures the difference between the electricity generated by the solar array and the electricity consumed by the customer. For example, if a solar array generates 1,000 kWh of electricity and the customer consumes 800 kWh during a billing cycle, the net metering system would record a credit of 200 kWh for the excess energy exported to the grid. The utility company would then subtract this credit from the customer’s total electricity consumption for the next billing cycle.

Inverter and Meter Requirements

Utility companies have specific requirements for inverters and meters used in grid-tied solar systems. For example, the inverter must be designed to meet the National Electric Code (NEC) requirements for grid-tie systems, and the meter must be certified by a third-party testing laboratory such as UL (Underwriters Laboratories) or CSA (Canadian Standards Association). The inverter and meter must also be compatible with the utility company’s grid management system to ensure accurate measurement of solar energy production.