Solar panels in Gaithersburg, MD
Roofs in Gaithersburg get about 1,516 hours of usable sunlight a year — less than 56% 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 Gaithersburg → City averages are a starting point; your own roof's size, pitch and shading change the answer a lot.
What a typical Gaithersburg solar system costs
A 21-panel system (8.4 kW) is about right for an average Gaithersburg home using 10,800 kWh a year. It would produce roughly 10,824 kWh annually and offset 100% of that usage.
| System | Size | kWh/yr | Net cost | Saves/yr | Payback |
|---|---|---|---|---|---|
| 8 panels | 3.2 kW | 4,124 | $6,384 | $755 | 8.5 yrs |
| 12 panels | 4.8 kW | 6,185 | $9,576 | $1,132 | 8.5 yrs |
| 16 panels | 6.4 kW | 8,247 | $12,768 | $1,509 | 8.5 yrs |
| 20 panels | 8 kW | 10,309 | $15,960 | $1,887 | 8.5 yrs |
| 26 panels | 10.4 kW | 13,401 | $20,748 | $2,095 | 9.9 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 Gaithersburg gets 1,516 sun hours
That figure comes from Google's analysis of real rooftops across Gaithersburg — 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 Gaithersburg reaches about 1,615 hours, roughly 7% better than typical.
The numbers behind this page
| Typical usable sunlight | 1,516 hrs/yr |
|---|---|
| Unshaded roof | 1,615 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.
Gaithersburg solar questions
How many solar panels do I need in Gaithersburg?
About 21 panels for an average home. Gaithersburg roofs get 1,516 usable sun hours a year, so each 400W panel produces roughly 515 kWh annually.
Is solar worth it in Gaithersburg?
At 18.3¢/kWh and 1,516 sun hours, a typical system pays for itself in about 8.5 years and returns roughly $32,680 over 25 years. That is a solid return.
How much do solar panels cost in Gaithersburg?
A 8.4 kW system costs about $23,940 before incentives and $16,758 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.