Solar Panel Calculator for Philadelphia, PA
Estimate the cost, savings and payback of solar panels in Philadelphia, PA, using local NREL sunshine data, Pennsylvania prices and electricity rates.
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Philadelphia gets about 4.81 peak sun hours a day on a south-facing roof, so each kW of panels makes about 1,364 kWh a year. That ranks #66 of the 111 cities on this site. Output peaks in Jul and is lowest in Dec.
Sunshine in Philadelphia by month
What an 8 kW system makes in Philadelphia
| Month | Sun hours a day | Output | Bill savings |
|---|---|---|---|
| Jan | 3.10 | 656 kWh | $139 |
| Feb | 4.29 | 808 kWh | $171 |
| Mar | 5.00 | 1,008 kWh | $213 |
| Apr | 5.77 | 1,080 kWh | $228 |
| May | 5.84 | 1,088 kWh | $230 |
| Jun | 6.18 | 1,104 kWh | $233 |
| Jul | 6.45 | 1,176 kWh | $248 |
| Aug | 5.65 | 1,016 kWh | $215 |
| Sep | 5.33 | 968 kWh | $205 |
| Oct | 4.30 | 840 kWh | $177 |
| Nov | 3.17 | 632 kWh | $134 |
| Dec | 2.69 | 560 kWh | $118 |
| Year | 4.81 | 10,912 kWh | $2,306 |
Savings at 21.13¢ per kWh (Pennsylvania average), with every kWh credited at that price.
Cost and payback by system size
At $2.60 per watt, the Pennsylvania average, before incentives.
| System | Cost | Year 1 savings | Payback | 25-yr gain |
|---|---|---|---|---|
| 4 kW | $10,400 | $1,153 | 9.2 yrs | $16,757 |
| 6 kW | $15,600 | $1,729 | 9.2 yrs | $25,135 |
| 8 kW | $20,800 | $2,306 | 9.2 yrs | $33,513 |
| 10 kW | $26,000 | $2,882 | 9.2 yrs | $41,891 |
| 12 kW | $31,200 | $3,459 | 9.2 yrs | $50,270 |
How many panels you need in Philadelphia
| Monthly use | System | 400 W panels |
|---|---|---|
| 500 kWh | 4.40 kW | 11 |
| 750 kWh | 6.60 kW | 17 |
| 1,000 kWh | 8.80 kW | 22 |
| 1,500 kWh | 13.20 kW | 33 |
| 2,000 kWh | 17.60 kW | 44 |
Covering 100% of a year's use at 1,364 kWh per kW.
Common questions
Is solar worth it in Philadelphia?
At local averages an 8 kW system costs about $20,800 before incentives, saves about $2,306 in its first year and pays back in about 9.2 years.
How many peak sun hours does Philadelphia get?
About 4.81 a day over the year on a south-facing roof at 20°, from 2.7 in Dec to 6.5 in Jul, according to NREL's PVWatts model.
How much does a 1 kW solar system produce in Philadelphia?
About 1,364 kWh a year, or 114 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