The Avoided Cost Calculator is a model maintained by the California Public Utilities Commission that estimates what a utility saves, hour by hour, when a customer supplies energy instead of the grid. Under the Net Billing Tariff for PG&E, SCE and SDG&E customers, exported solar is credited at these hourly values, which vary by month, weekday and time of day. Values are typically low in sunny midday hours, when solar floods the grid, and higher on summer evenings. New customers lock in the export value schedule for their application year for a number of years. The practical effect is that a battery that shifts midday solar into the evening peak can earn far more than exporting at noon.
Related terms and pages
- Net billing: Billing in which exported solar is credited at a rate below what you pay for power.
- Time-of-use rate: An electricity rate whose price per kWh depends on the hour, highest in the evening peak.
- Round-trip efficiency: The share of energy put into a battery that you can get back out.
- How California credits exports