Solar Companies in San Mateo County: Who Installed the Most Systems in 2025

Installers who connected the most home solar systems in San Mateo County in 2025

Counts from utility records, not a ranking or endorsement. Check each license's status and complaint history on the CSLB's Check a License page (checked Sept. 24, 2026). The counts cover PG&E customers across San Mateo County; customers of city-owned utilities are not in the data.

Source: California Distributed Generation Statistics (CPUC), Interconnected Project Sites data set, data through May 31, 2026 (checked Sept. 24, 2026).

Home solar in San Mateo County by the numbers

PG&E approved 2,230 home solar systems in San Mateo County in 2025, from 212 installers; the top three were named on 34% of them. The busiest year since 2021 was 2023, with 3,568 (2025: -37%). Another 1,218 were approved from January through May 2026.

2025 mix: 28% leased or on a power purchase agreement, 73% owned by the household; 55% with a battery; median size 6.8 kW DC.

Permit offices and providers across San Mateo County

The utility map is simple here. On the California Energy Commission's layers, PG&E is the delivery utility across the county's inhabited area and WestLight Energy, still labeled Peninsula Clean Energy on the Commission's map, is the community choice provider over the same area. WestLight describes itself as the community electricity provider for San Mateo County and Los Banos.

Permitting is where the county divides. Under Government Code section 65850.52, cities with more than 50,000 people had to offer an online, automated solar permit such as SolarAPP+ by September 30, 2023, and smaller cities by September 30, 2024. The last column shows what each jurisdiction reported to the Energy Commission for 2024: residential solar permits issued, the share that included battery storage, and the share issued online.

Permit counts are each jurisdiction's own annual report under SB 379, from the Energy Commission's data file dated May 2026; a city that has not filed does not appear. A higher count reflects local demand and how many homes a city has, not how fast or friendly its process is.

For what each of these utilities charges today, see Bay Area electric rates and community choice providers.

Hiring a solar company in San Mateo County

Solar companies working in San Mateo County design around PG&E, which delivers the power, and WestLight Energy, formerly Peninsula Clean Energy, which supplies it. The permit office depends on the address: each city issues its own permits, and the County of San Mateo permits unincorporated homes instantly through Symbium. The cities' 2024 reports to the Energy Commission show online permitting ranging from none to all. Compare at least three written bids built on your own bill.

Start with your San Mateo County electricity bill

Almost every home in San Mateo County has the same two names on its bill: PG&E delivers the power and sends the statement, and WestLight Energy, the county's community choice provider that used to be called Peninsula Clean Energy, supplies the generation. WestLight tells readers that 97% of their neighbors in San Mateo County and Los Banos get electricity from it. A proposal should model WestLight's generation side and PG&E's delivery side separately, from your own account.

How WestLight and PG&E split a solar bill

Peninsula Clean Energy renamed itself WestLight Energy and says its service and rates did not change. WestLight's generation charges and credits appear on the monthly PG&E statement next to PG&E's delivery charges. On its net energy metering schedule, WestLight values a month of net production at the customer's generation rate plus a production premium of $0.01 per kWh, settles its generation charges monthly, and after the April billing cycle mails a check to customers whose credit balance is over $500. Since the 2024-2025 NEM year the annual cash-out is capped at $10,000, and anything above the cap is forfeited.

PG&E handles the delivery side under its own rules. A new system goes on PG&E's Solar Billing Plan, where export credits vary by time of day, day of the week and season, customers who start before 2028 get Energy Export Bonus Credits whose value is set at permission to operate, and a True-Up statement closes each 12-month cycle. PG&E says customers save the most when they use the energy they produce on-site. A proposal that shows one blended credit for all exports is hiding both of these schedules.

What the 2024 permit reports say about each city

Every jurisdiction that adopted an automated permit platform must report its residential solar permits to the California Energy Commission each year. The 2024 numbers for San Mateo County's cities vary widely. Belmont, Pacifica, South San Francisco, San Bruno and Atherton reported every solar permit as issued online, while Foster City reported none online, Burlingame 23% and San Mateo 31%. Storage varied too: 83% of San Carlos's 2024 permits and 76% of Belmont's included a battery, compared with 41% in San Bruno.

For a homeowner, the online share is a practical signal. Where most permits are issued online, a qualifying design can be permitted the same day, and the schedule depends more on the installer than the city. Where most go through plan check, ask the bidder how long its last few permits in your city took. The City of San Mateo adds its own conditions to SolarAPP+: the contractor needs an active San Mateo business license and must ask to be put on the City's eligibility list.

What a San Mateo County quote needs to explain

A comparison to ask for

Ask each bidder three questions before comparing prices: which office will issue your permit and through which system, whether the design includes a battery and how many kWh of it you can actually use, and how the estimate splits WestLight generation credits from PG&E delivery charges. A bid that cannot answer the first question has not looked at your address yet.

Verify the company behind the San Mateo County quote

Match the business name and license number on each San Mateo County proposal to the CSLB record, then use our contractor verification steps, the quote comparison guide and the PPA, loan, lease and cash comparison.

San Mateo County solar quote questions