System size determines both cost and paybackSolar systems are sized in kilowatts (kW). A typical San Francisco home uses 10,000–14,000 kWh/year, requiring a 7–10 kW system. Larger systems cost more upfront but generate more excess power for net metering credits. Your electricity bill and roof space determine the optimal size — a reputable installer will provide a custom production estimate before quoting.
Federal tax credit significantly reduces net costThe federal Investment Tax Credit (ITC) currently covers 30% of solar installation costs with no cap. On a $43,750 system, that's $13,125 back. This credit is taken as a reduction in your federal income tax owed — it requires sufficient tax liability to claim in full. Your net cost after the ITC is $30,624, not $43,750. Many San Francisco utilities and states offer additional rebates on top of the federal credit.
Roof condition must be addressed before panels are installedSolar panels have a 25–30 year lifespan. Installing them on a roof with less than 10–15 years of life remaining means removing and reinstalling the panels when the roof needs replacement — adding $2,000–$5,000 in additional cost. Have your roof independently inspected before committing to solar. In San Francisco, seasonal factors affect pricing affects how quickly roofing materials age.
Net metering policy determines return on investmentNet metering allows you to sell excess solar generation back to your utility at retail rates — dramatically improving payback. Net metering policies vary significantly by state and utility in San Francisco. If your utility offers full retail net metering, payback periods are typically 6–9 years. If net metering has been reduced or eliminated, payback extends significantly. Verify your current utility's net metering rate before making a final decision.
Panel brand and warranty matter over a 25-year horizonTier-1 panels (LG, Panasonic, SunPower, Qcells) carry 25-year product and performance warranties backed by financially stable manufacturers. Budget panels from unknown brands may offer the same warranty on paper but provide no practical recourse if the manufacturer fails in year 8. The premium for Tier-1 panels is typically $500–$1,500 on a full system — worth it for a 25-year asset.
Installer certification and local track recordLook for installers with NABCEP (North American Board of Certified Energy Practitioners) certification — the industry's highest credential. In San Francisco, check references from installations done at least 3–5 years ago to evaluate long-term service. Avoid large national companies that use inexperienced local subcontractors — local installers with NABCEP certification and verifiable local references are the gold standard.