What the sun is worth on your roof

Drag the slider to your average monthly bill. Every number below updates instantly, and every assumption behind it is listed at the bottom — nothing hidden.

How this estimate is built (edit the constants at the top of the script to match your own pricing): Assumes a blended PG&E residential rate of $0.39/kWh (PG&E’s bundled average rate schedule, March 2026) plus PG&E’s Base Services Charge of roughly $24/month; an installed cost of $2.75/W (California 2026 market range is roughly $2.40–$3.15/W); Bay Area production of ~1,500 kWh per kW per year; a system sized to offset ~90% of usage, which is typical design practice under the Net Billing Tariff (NEM 3.0, upheld by the California Court of Appeal in March 2026); 4%/year utility rate growth — treat this as uncertain, since PG&E rates have actually fallen five times since January 2024 but the utility has separately sought rate increases for 2027–2030; and 0.5%/year panel degradation. Battery storage adds an estimated $12,000. The 30% federal residential tax credit (Section 25D) ended December 31, 2025 and is not included; it may still apply indirectly to lease or PPA financing, where the financing company retains the commercial credit. This tool provides estimates for illustration only, not a quote or financial advice — actual savings depend on roof, shading, financing, current rates, and incentives at time of install.