Iowa Net Metering Rules for Distributed Solar Generation

The Iowa Utilities Commission enforces section 476.49. To qualify as an "eligible distributed generation facility," an on-site solar array must sit behind the customer's electricity meter, interconnect to the utility distribution system, stay at or below one megawatt of alternating-current nameplate capacity, and be sized to produce no more than 110 percent of the customer's annual electricity use. Interstate Power and Light and MidAmerican Energy each file either a net billing or an inflow-outflow tariff. Under inflow-outflow billing, exported energy is credited in dollars at the retail volumetric outflow rate, fixed for a twenty-year term regardless of ownership changes.

A solar array over one megawatt, or sized above 110 percent of annual usage, is not an eligible facility and loses net-metering crediting. Utilities enforce the caps through Iowa Utilities Commission-approved interconnection tariffs rather than fines.