Solar panels in San Francisco, CA
Roofs in San Francisco get about 1,819 hours of usable sunlight a year — more than 85% of the cities we've measured. Here's what that means in cost, savings and payback, using real rooftop data rather than a national average.
Check your specific roof in San Francisco → City averages are a starting point; your own roof's size, pitch and shading change the answer a lot.
What a typical San Francisco solar system costs
A 18-panel system (7.2 kW) is about right for an average San Francisco home using 10,800 kWh a year. It would produce roughly 11,132 kWh annually and offset 100% of that usage.
| System | Size | kWh/yr | Net cost | Saves/yr | Payback |
|---|---|---|---|---|---|
| 8 panels | 3.2 kW | 4,948 | $6,384 | $1,252 | 5.1 yrs |
| 12 panels | 4.8 kW | 7,422 | $9,576 | $1,407 | 6.8 yrs |
| 16 panels | 6.4 kW | 9,895 | $12,768 | $1,561 | 8.2 yrs |
| 20 panels | 8 kW | 12,369 | $15,960 | $1,715 | 9.3 yrs |
| 26 panels | 10.4 kW | 16,080 | $20,748 | $1,947 | 10.7 yrs |
How we worked this out for San Francisco
Every number on this page comes from these seven steps. Nothing is a national average — the sunlight figure is measured from San Francisco rooftops.
| # | Step | Result |
|---|---|---|
| 1 | What one panel makes here 400W ÷ 1000 × 1,819 sun hrs × 0.85 system losses |
618 kWh/yr |
| 2 | Panels needed to cover typical usage 10,800 kWh ÷ 618 kWh per panel |
18 panels |
| 3 | System size 18 panels × 400W |
7.20 kW |
| 4 | Annual production 7.20 kW × 1,819 hrs × 0.85 |
11,132 kWh/yr |
| 5 | Installed cost 7,200 W × $2.85 per watt, then −30% federal credit |
$14,364 |
| 6 | Annual saving 3,780 kWh used as generated × 31.2¢ + 7,352 kWh exported × 6.2¢ |
$1,638/yr |
| 7 | Payback $14,364 ÷ $1,638 per year |
8.8 years |
Step 6 is where most calculators quietly overstate things. Only 34% of what a system this size produces in San Francisco is used the moment it is generated; the other 7,352 kWh is exported and credited at 20% of retail under net billing. Valuing every kWh at the full 31.2¢ retail rate — which many calculators do — would show a payback of 4.1 years instead of the 8.8 we show. That 4.7-year difference is the single biggest reason our figures look worse than other sites' for San Francisco.
Assumptions: 400W panels, 15% system losses (inverter, wiring, heat, soiling), $2.85/W installed, 10,800 kWh typical annual household use, 31.2¢/kWh electricity. Change any of those and every figure above moves — which is exactly why a single national "solar costs X" number is misleading.
Notice that payback barely improves as systems get bigger, and eventually gets worse. That's because you can only save money on electricity you were going to buy anyway. Once a system covers your usage, extra panels mostly generate exports at a much lower rate.
Why San Francisco gets 1,819 sun hours
That figure comes from Google's analysis of real rooftops across San Francisco — it already accounts for shading from trees, chimneys and neighbouring buildings, which is why it's lower than the raw "hours of daylight" figures you'll see elsewhere. An unusually open, unshaded roof in San Francisco reaches about 1,931 hours, roughly 6% better than typical.
The numbers behind this page
| Typical usable sunlight | 1,819 hrs/yr |
|---|---|
| Unshaded roof | 1,931 hrs/yr |
| Electricity rate (California avg) | 31.2¢/kWh |
| Installed cost assumed | $2.85/W |
| Panel size assumed | 400 W |
| Federal tax credit | 30% |
| Typical household usage | 10,800 kWh/yr |
| Power used as generated | 34% |
| Paid for exported power | 20% of retail |
| Rooftops sampled here | 6 |
| Google imagery from | 2024 |
When San Francisco actually produces
Annual totals hide the thing that catches people out: 35% of San Francisco's yearly sunlight arrives in May–July, and just 14% across November–January.
| Month | Sun hrs | Share of year |
|---|---|---|
| Jan | 86 | |
| Feb | 114 | |
| Mar | 148 | |
| Apr | 184 | |
| May | 208 | |
| Jun | 218 | |
| Jul | 212 | |
| Aug | 193 | |
| Sep | 161 | |
| Oct | 124 | |
| Nov | 93 | |
| Dec | 79 |
San Francisco produces about 2.8× as much in Jun as in Dec — a normal mid-latitude swing. Expect real winter shortfall and summer surplus rather than steady year-round output.
The annual total is measured from Google's rooftop imagery. Its split across months is calculated from solar geometry at San Francisco's latitude, not separately measured, so treat the monthly figures as the shape of a typical year rather than a forecast.
How San Francisco compares to the other 788 cities
| Measure | San Francisco | Rank of 788 |
|---|---|---|
| Usable sunlight | 1,819 hrs | 121st |
| Sunlight lost to shade | 6% | 326th most |
| Median roof size | 75 m² | 752nd largest |
| Electricity rate | 31.2¢ | 11th highest |
| Payback | 8.8 yrs | 202nd fastest |
| Grid carbon | 429 kg/MWh | 662nd dirtiest |
What actually stands out about San Francisco:
- Roof space is the binding constraint. A typical San Francisco roof fits about 25 panels and a typical home needs 18 — so there is little room to oversize. If you add an EV or heat pump later, plan the array for it now.
- Small roofs. The median San Francisco roof is 75 m², smaller than 95% of cities measured — worth checking your own footprint before assuming a standard system fits.
- Expensive electricity works in your favour. At 31.2¢/kWh, California is among the priciest places to buy power — which is exactly what makes generating your own pay back faster.
Cities with almost the same sunlight
These are the closest matches to San Francisco's 1,819 usable sun hours from other states and provinces. Same sunlight, different electricity prices — which is usually what decides whether solar is worth it.
| City | Sun hrs | Rate | Payback |
|---|---|---|---|
| Aurora, CO | 1,821 | 14.8¢ | 8.9 yrs |
| Elko, NV | 1,821 | 15.3¢ | 8.6 yrs |
| Pueblo, CO | 1,822 | 14.8¢ | 8.9 yrs |
| Clearwater, FL | 1,813 | 15.3¢ | 8.6 yrs |
Nearby cities
See all of California → statewide sunlight, rates, incentives and every city we've measured.
San Francisco solar questions
How many solar panels do I need in San Francisco?
About 18 panels for an average home using 10,800 kWh a year. San Francisco roofs get 1,819 usable sun hours, so each 400W panel produces roughly 618 kWh annually. A typical San Francisco roof fits about 25 panels, so check your usable roof area before assuming that many will fit.
Is solar worth it in San Francisco?
At 31.2¢/kWh and 1,819 sun hours, a typical system pays for itself in about 8.8 years and returns roughly $26,590 over a 25-year panel life. That is a solid return, and it improves further if electricity prices rise. Exports earn only 20% of retail, so using power as you generate it matters.
How much do solar panels cost in San Francisco?
A 7.2 kW system costs about $20,520 before incentives and $14,364 after the 30% federal tax credit. That works out near $2.85 per watt installed. Roof pitch, shading, electrical panel upgrades and equipment choice move the price most, which is why quotes for the same house can differ by thousands.
Worth reading before you buy
Estimates only, generated 2026-08-22 from Google Solar API rooftop samples and average California electricity rates. Not a quote and not financial advice. Your roof, usage, utility plan and local incentives will change these numbers — get real quotes before buying.