Local governments in California review designs and inspect installed systems to ensure that on-site solar installations comply with local building codes, while electric utilities approve related grid interconnections. The cumulative result of their permitting activity is summarized in the map below[1], which shows about half of solar electricity deployment in California to date has been local, aka “behind the meter”. By contrast, the U.S. has a utility solar sector four times as large as its local (combined residential and non-residential) solar sectors.
Geographic Distribution of Renewable Electricity Capacity in California (Source: California Energy Commission)
California’s solar power deployment experience can inform its GHG reduction goal setting. For example, what is the best state-wide balance between centralized renewable supply expansion and locally beneficial on-site and community renewable energy deployment? The best local balance will vary because renewable resource opportunities and energy usage patterns differ significantly from one community to the next. Achieving the best local balance will require that local governments reach out and engage with energy service providers, energy users, local solar retailers and energy engineers.
Trade-offs between centralized and local renewable energy production affect the balance between local energy exports and imports. The map shows that every California county produces renewable energy. Some counties are net exporters; most are net importers. Each exporting county’s renewable product mix differs from others. Most electricity generated by “utility scale” solar power plants in high production counties is exported via California’s state-wide power grid and sent to other counties. Transmission charges on these exports now exceed solar power plant bus-bar costs by as much as a factor of two and continue to escalate.
Expansion of renewable energy production confronts local trade-offs as well. For example, locally produced solar electricity is typically not available to renters or residents in low income neighborhoods, resulting in “solar energy deserts” akin to “food deserts”. “Community solar”[2] projects provide an equitable antidote that can work for municipal electric utilities and the communities they serve, because municipal utilities are not state regulated and can price electricity from local solar projects at project-specific costs of production and transport.
California’s state-regulated utilities apply the same transmission charges to all the electricity they purchase regardless of how far it travels from source to point of use; they earn profits indexed to the book value of their energy transport assets. Thus, they prefer to offer “solar tariffs” for solar electricity they purchase from utility scale projects feeding into their transmission systems virtually rather than physically.
Can expansion of renewable energy production in the U.S. be accelerated if “wires charges”[3] for community renewable projects are adjusted to account for local energy resilience benefits and actual project-specific transmission grid usage? How much costly and environmentally controversial expansion of regional transmission systems can be avoided by expanding local renewable energy production for local use?
[1] https://cecgis-caenergy.opendata.arcgis.com/pages/pdf-maps
[2] https://www.seia.org/initiatives/community-solar
[3] Charges intended to recover costs of electricity transmission and distribution.