Solar panels in Petaluma: what they cost and what they make
A typical Petaluma home needs 9 solar panels. They would make about 6,098 kWh a year and cost $9,500 to $14k before incentives. At today's electricity prices they pay for themselves in about 9.3 yrs.
See panels on your own Petaluma roof
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What solar costs in Petaluma
At $3.00 a watt, the median price cash buyers pay nationally, a 3.8 kW system costs about $11,400. Quotes in Petaluma will usually fall between $9,500 and $14,250. Complex roofs, main-panel upgrades and financing push prices up.
The 30% federal tax credit no longer applies to systems homeowners buy. This estimate includes no state or utility incentives; check with your utility before you buy.
The number that decides whether solar pays in Petaluma is what your utility pays for the power you send back. California’s Net Billing Tariff (since Apr 15, 2023) credits exports at Avoided Cost Calculator values, locked for 9 years per vintage. Under full payback is about 5.6 yrs. Under net billing it is about 9.3 yrs, because only the ~43% of solar a typical home uses as it is made saves the full retail price.
Cash purchase, prices rising 2.5% a year, panels losing 0.5% a year, $25/kW a year for upkeep. No federal credit for homeowner-owned systems.
Every way to pay for a 3.8 kW system in Petaluma
Change any number →| Way to pay | Day one | Monthly payment | Monthly net, year 1 | Ahead after 25 years |
|---|---|---|---|---|
| Pay cash Full price on install day | $11,400 | $0 | +$94 | $25k |
| Credit-union loan 8% APR, 20 years, no dealer fee | $0 | $95 | −$2 | $14k |
| “1.99%” solar loan 1.99% APR, 25 years, 25% dealer fee | $0 | $60 | +$33 | $18k |
| Lease $85/mo, +2.9%/yr | $0 | $85 | +$17 | $2,300 |
| Power purchase (PPA) 17.0¢/kWh, +2.9%/yr | $0 | $86 | +$15 | $4,100 |
Under net billing, the usual rule for new customers here, at 33.3¢/kWh rising 2.5% a year. The “1.99%” loan’s $2,850 dealer fee is included in its payments. Lease and PPA prices are typical offers, not quotes.
How much sunshine Petaluma gets
kWh per kW, 25° southJun is the best month for solar in Petaluma, and Dec the weakest: a Dec day makes 48% of a Jun day. A 6 kW system would make about 485 kWh in Dec and 1,018 kWh in Jun.
On June 21 the sun rises at 5:47 am and sets at 8:37 pm, 14 hours 50 minutes of daylight. On December 21 it is up from 7:23 am to 4:53 pm, just 9 hours 30 minutes.
Peak sun hours in Petaluma, month by month
| Month | Flat ground | Panels at 33° | kWh per kW |
|---|---|---|---|
| Jan | 2.3 | 3.9 | 90 |
| Feb | 3.3 | 4.8 | 102 |
| Mar | 4.6 | 5.7 | 136 |
| Apr | 6.0 | 6.4 | 153 |
| May | 7.1 | 6.7 | 168 |
| Jun | 7.8 | 7.0 | 170 |
| Jul | 7.5 | 6.8 | 169 |
| Aug | 6.6 | 6.7 | 162 |
| Sep | 5.6 | 6.7 | 150 |
| Oct | 4.1 | 5.8 | 133 |
| Nov | 2.8 | 4.6 | 101 |
| Dec | 2.0 | 3.5 | 81 |
| Year | 5.0 | 5.7 | 1,613 |
A peak sun hour is one hour of sunlight at 1,000 W per m². Why sites disagree.
The best angle and direction for panels in Petaluma
| Roof faces (6/12 pitch) | Output vs south | kWh per kW |
|---|---|---|
| South | 100% | 1,613 |
| Southeast | 96% | 1,548 |
| Southwest | 95% | 1,532 |
| East | 83% | 1,339 |
| West | 83% | 1,339 |
| North | 60% | 968 |
Face panels south and tilt them 33° for the most energy over a year. East and west roofs keep about 83% of that. A north-facing roof keeps 60%, which is rarely worth the money. Try other angles.
Where the sun goes over Petaluma
The noon sun is lower in winter, which is why the best winter tilt (61°) is steeper than the best summer tilt (9°).
Petaluma's homes
Petaluma has 24,239 households. 64.5% own their home, and 14,669 of those owners live in single-family houses, the kind of home that usually gets rooftop solar.
The median home here was built in 1979. Many roofs that age are due for replacement. Replace the roof first, then add solar: taking panels off and putting them back later costs thousands.
22.6% of homes heat with electricity and 73.8% with gas. If you switch to a heat pump or an electric car, plan for more panels or leave room on the roof.
Source: U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates.
If the power goes out in Petaluma
Solar panels alone shut off in a blackout. Add a battery and they keep going. One Tesla Powerwall 3 (13.5 kWh) running a fridge, freezer, furnace fan, lights, Wi-Fi, TV and microwave (6.9 kWh a day):
Change the appliances, the battery and the weather in the battery calculator.
Questions people ask about solar in Petaluma
How much do solar panels cost in Petaluma?
A 3.8 kW system — enough for the average California home — costs about $9,500 to $14,250 before incentives, based on $2.50–$3.75 per watt. The 30% federal credit no longer applies to systems homeowners buy.
How many solar panels does a house in Petaluma need?
About 9 panels of 420 watts for a home using 503 kWh a month, the California average. Each kilowatt of panels here makes about 1,613 kWh a year on a south-facing roof.
Is solar worth it in Petaluma?
Over 25 years, solar power here costs about 9.5¢ per kWh, against 33.3¢ from the grid today. Payback is about 5.6 yrs if your utility credits exported power at the full retail rate, and 9.3 yrs if it pays about 30% of retail. Most new customers in California are on the lower rate.
How many peak sun hours does Petaluma get?
5.7 a day on panels tilted to 33°, and 5.0 on flat ground. The best month is Jun; the weakest is Dec.
What is the best angle for solar panels in Petaluma?
33° for the most energy over a year, facing south. 61° is best in winter and 9° in summer. On a normal pitched roof, anything within 15° of 33° gives you about 95% of the maximum.
How long would a home battery last in a Petaluma power outage?
A Tesla Powerwall 3 running a fridge, freezer, furnace fan, lights, Wi-Fi, TV and microwave (6.9 kWh a day) lasts about 43 hours with no sun. With 7 kW of solar to recharge it, it gets through a three-day outage even in overcast January.
Solar near Petaluma
| City | Miles | kWh per kW | Sun hours |
|---|---|---|---|
| Novato, CA | 12 | 1,623 | 5.7 |
| Santa Rosa, CA | 15 | 1,636 | 5.8 |
| Napa, CA | 18 | 1,649 | 5.9 |
| San Rafael, CA | 19 | 1,619 | 5.7 |
| Vallejo, CA | 22 | 1,641 | 5.8 |
Petaluma shares a weather-data neighbourhood with Santa Rosa; their sunshine numbers differ by less than our data can resolve. Housing, prices and outage figures are specific to Petaluma.
Cities with the same sunshine as Petaluma
These far-away cities get almost exactly as much solar energy per panel.
- San Angelo, TX 1,626 kWh per kW
- Abilene, TX 1,616 kWh per kW
- Denver, CO 1,642 kWh per kW
Sources: NASA POWER 2001–2020 monthly climatology (grid cell 31 km from Petaluma's Census point), our PV model (within 1.6% of NLR PVWatts® on average), U.S. EIA prices and use, U.S. Census 2025 population estimates and ACS 2020–2024. Estimates for an average home, not a site survey. How we calculate.