Solar panels in Rockville, MD
Roofs in Rockville get about 1,453 hours of usable sunlight a year — less than 68% 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 Rockville → City averages are a starting point; your own roof's size, pitch and shading change the answer a lot.
What a typical Rockville solar system costs
A 22-panel system (8.8 kW) is about right for an average Rockville home using 10,800 kWh a year. It would produce roughly 10,868 kWh annually and offset 100% of that usage.
| System | Size | kWh/yr | Net cost | Saves/yr | Payback |
|---|---|---|---|---|---|
| 8 panels | 3.2 kW | 3,952 | $6,384 | $723 | 8.8 yrs |
| 12 panels | 4.8 kW | 5,928 | $9,576 | $1,085 | 8.8 yrs |
| 16 panels | 6.4 kW | 7,904 | $12,768 | $1,446 | 8.8 yrs |
| 20 panels | 8 kW | 9,880 | $15,960 | $1,808 | 8.8 yrs |
| 26 panels | 10.4 kW | 12,845 | $20,748 | $2,070 | 10 yrs |
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 Rockville gets 1,453 sun hours
That figure comes from Google's analysis of real rooftops across Rockville — 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 Rockville reaches about 1,574 hours, roughly 8% better than typical.
The numbers behind this page
| Typical usable sunlight | 1,453 hrs/yr |
|---|---|
| Unshaded roof | 1,574 hrs/yr |
| Electricity rate (Maryland avg) | 18.3¢/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 | 35% |
| Paid for exported power | full retail (net metering) |
| Rooftops sampled here | 15 |
| Google imagery from | 2018 |
Nearby cities
See all of Maryland → statewide sunlight, rates, incentives and every city we've measured.
Rockville solar questions
How many solar panels do I need in Rockville?
About 22 panels for an average home. Rockville roofs get 1,453 usable sun hours a year, so each 400W panel produces roughly 494 kWh annually.
Is solar worth it in Rockville?
At 18.3¢/kWh and 1,453 sun hours, a typical system pays for itself in about 8.9 years and returns roughly $31,932 over 25 years. That is a solid return.
How much do solar panels cost in Rockville?
A 8.8 kW system costs about $25,080 before incentives and $17,556 after the 30% federal tax credit. Prices vary by installer, roof complexity and equipment.
Worth reading before you buy
Estimates only, generated 2026-08-22 from Google Solar API rooftop samples and average Maryland 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.