Solar Panel Calculator for Boston, MA
Estimate the cost, savings and payback of solar panels in Boston, MA, using local NREL sunshine data, Massachusetts prices and electricity rates.
Your result
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Boston gets about 4.70 peak sun hours a day on a south-facing roof, so each kW of panels makes about 1,302 kWh a year. That ranks #75 of the 111 cities on this site. Output peaks in Jul and is lowest in Dec.
Sunshine in Boston by month
What an 8 kW system makes in Boston
| Month | Sun hours a day | Output | Bill savings |
|---|---|---|---|
| Jan | 3.15 | 648 kWh | $196 |
| Feb | 3.92 | 720 kWh | $217 |
| Mar | 5.00 | 992 kWh | $299 |
| Apr | 5.43 | 992 kWh | $299 |
| May | 6.12 | 1,112 kWh | $336 |
| Jun | 5.89 | 1,024 kWh | $309 |
| Jul | 6.46 | 1,144 kWh | $345 |
| Aug | 5.92 | 1,048 kWh | $316 |
| Sep | 5.29 | 928 kWh | $280 |
| Oct | 3.99 | 760 kWh | $229 |
| Nov | 2.92 | 568 kWh | $171 |
| Dec | 2.30 | 472 kWh | $142 |
| Year | 4.70 | 10,416 kWh | $3,145 |
Savings at 30.19¢ per kWh (Massachusetts average), with every kWh credited at that price.
Cost and payback by system size
At $2.90 per watt, the Massachusetts average, before incentives.
| System | Cost | Year 1 savings | Payback | 25-yr gain |
|---|---|---|---|---|
| 4 kW | $11,600 | $1,572 | 7.5 yrs | $25,437 |
| 6 kW | $17,400 | $2,358 | 7.5 yrs | $38,155 |
| 8 kW | $23,200 | $3,145 | 7.5 yrs | $50,874 |
| 10 kW | $29,000 | $3,931 | 7.5 yrs | $63,592 |
| 12 kW | $34,800 | $4,717 | 7.5 yrs | $76,311 |
How many panels you need in Boston
| Monthly use | System | 400 W panels |
|---|---|---|
| 500 kWh | 4.61 kW | 12 |
| 750 kWh | 6.91 kW | 18 |
| 1,000 kWh | 9.22 kW | 24 |
| 1,500 kWh | 13.82 kW | 35 |
| 2,000 kWh | 18.43 kW | 47 |
Covering 100% of a year's use at 1,302 kWh per kW.
Common questions
Is solar worth it in Boston?
At local averages an 8 kW system costs about $23,200 before incentives, saves about $3,145 in its first year and pays back in about 7.5 years.
How many peak sun hours does Boston get?
About 4.70 a day over the year on a south-facing roof at 20°, from 2.3 in Dec to 6.5 in Jul, according to NREL's PVWatts model.
How much does a 1 kW solar system produce in Boston?
About 1,302 kWh a year, or 108 kWh a month on average.
Is there a federal solar tax credit?
Not for homeowners who buy their system. The 30% Residential Clean Energy Credit ended for systems installed after December 31, 2025.
Sources
- NREL PVWatts V8 API (south-facing, 20° tilt, 14% losses, typical-year weather): https://developer.nlr.gov/docs/solar/pvwatts/v8/
- EnergySage, Solar panel cost by state (updated November 6, 2026): https://www.energysage.com/local-data/solar-panel-cost/
- U.S. EIA, Electric Power Monthly, Table 5.6.B (residential price, Jan–Aug 2026): https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_b