Solar panels in Modesto, CA

Roofs in Modesto get about 1,900 hours of usable sunlight a year — more than 89% 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 Modesto → City averages are a starting point; your own roof's size, pitch and shading change the answer a lot.

What a typical Modesto solar system costs

A 17-panel system (6.8 kW) is about right for an average Modesto home using 10,800 kWh a year. It would produce roughly 10,982 kWh annually and offset 100% of that usage.

How we worked this out for Modesto

Every number on this page comes from these seven steps. Nothing is a national average — the sunlight figure is measured from Modesto rooftops.

Step 6 is where most calculators quietly overstate things. Only 34% of what a system this size produces in Modesto is used the moment it is generated; the other 7,202 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 4.0 years instead of the 8.3 we show. That 4.3-year difference is the single biggest reason our figures look worse than other sites' for Modesto.

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 Modesto gets 1,900 sun hours

That figure comes from Google's analysis of real rooftops across Modesto — 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 Modesto reaches about 1,945 hours, roughly 2% better than typical.

The numbers behind this page

When Modesto actually produces

Annual totals hide the thing that catches people out: 35% of Modesto's yearly sunlight arrives in May–July, and just 14% across November–January.

Modesto produces about 2.7× 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 Modesto's latitude, not separately measured, so treat the monthly figures as the shape of a typical year rather than a forecast.

How Modesto compares to the other 788 cities

What actually stands out about Modesto:

• Unusually open roofs. Only 2% of available sunlight is lost to obstruction in Modesto — better than all but 91 of the 788 cities measured. Most roofs here get close to their theoretical maximum.
• Plenty of roof to work with. Typical roofs here fit around 86 panels — roughly 5× what an average home needs. Roof size will not be what limits your system in Modesto.
• The case here is financial, not environmental. Modesto's grid is already clean at 429 kg CO₂ per MWh, so the carbon saving from solar is modest. Judge this one on payback.
• 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 Modesto's 1,900 usable sun hours from other states and provinces. Same sunlight, different electricity prices — which is usually what decides whether solar is worth it.

Nearby cities

See all of California → statewide sunlight, rates, incentives and every city we've measured.

Modesto solar questions

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.