Wow! California homeowners have installed a total of nearly two million rooftop solar systems, representing a staggering 18,000 MW of generating capacity.[1]
One of every six homes in California now uses solar energy directly from their own rooftop.
At an estimated capacity factor of 17%, rooftop solar generates nearly 10% of California’s total electrical consumption of 281 TWh.[2]
In another surprise, nearly 1,400 MW of rooftop solar was installed in 2024 despite the state’s best effort to roll back new installations.
The California Public Utility Commission revised the state’s net metering policy recently making rooftop solar uneconomic without accompanying batteries. Consequently, there are now 3,000 MW of battery storage “behind the meter” from some 150,000 home battery systems.
The state continues to aggressively develop utility-scale battery back up. There are now 11,000 MW of utility-scale batteries in operation and another 3,000 MW under construction in California. With more than 3,000 MW of its existing pumped hydro storage, the state will soon have nearly 20,000 MW of storage to balance renewable resources.[3]
In more good news, California’s total electrical consumption has declined 8.5% from its peak in 2008 of 307 TWh per year as the state’s energy conservation policies increasingly take effect.[4]
While I’ve often been a critic of California energy policy, the state’s success developing its rooftop solar resource is hard to ignore. For North America, California continues to lead the way in rooftop solar. The state’s success is comparable to that in Germany where there’s 38,000 MW of rooftop solar for a population twice the size of California.
See also We Went Solar and What an Education it Was.
[1] California Distributed Generation Statistics. Note that the headline figure includes rooftop solar from municipal utilities while the chart only shows data for the Investor Owned Utilities or IOUs.
[2] CEC 2023 Total System Electric Generation. The estimate of rooftop solar capacity factor was provided by Robert Freehling, a private consultant on energy policy in California. Accordingly, rooftop solar generates nearly 27 TWh annually. “In 2023 alone, more than 45,000 behind-the-meter battery energy storage systems were installed in California, bringing the statewide total to approximately 150,000 systems.”
[3] Capacity of pumped storage hydropower plants in the United States in 2023, by state. California has 3,700 MW of pumped storage.
[4] Own data. Current CEC data publicly available only goes back to 2009.
