Skip to content
Loudoun County Dominion

Solar panels in South Riding, Virginia: 1,371 kWh per kW per year

A south-facing kilowatt of panels in South Riding makes about 1,371 kWh a year, 0.4% above the Virginia median. Power here comes from Dominion Energy at 15.20¢ per kWh (2025 average).

1,371

kWh / kW / year

PVWatts, south-facing

4.87

Peak sun hours / day

annual average irradiance

10,968

kWh / yr from 8 kW

a common home system

15.20¢

Dominion price

2025 residential avg

Monthly solar production per kW in South Riding, VirginiaKilowatt-hours per month for a 1 kW south-facing system. Peak in May, low in Dec.050100150Jan86Feb86Mar120Apr132May143Jun136Jul142Aug134Sep114Oct112Nov90Dec78
NREL PVWatts v8, 1 kW DC, fixed roof mount, azimuth 180°, tilt 25°, 14% losses. May makes about 1.8× Dec.

Seasonality

Monthly solar production in South Riding

Virginia net metering carries excess credits forward for 12 months, so May's surplus offsets Dec's shortfall. Systems are sized to annual usage rather than to the lowest month. How the calculator models net metering; the current rules by utility are on this Virginia incentives page, maintained by the installer behind this site.

Capacity factor: 15.7%. Elevation about 102 m. Compare every town on the city list, or see how roof direction, tilt and shade change the number.

Payback in South Riding

Solar cost and payback for an average home in South Riding

Assumes 1,038 kWh a month (≈ $158) at Dominion Energy's 2025 average price, South Riding's PVWatts production, 3% annual rate growth and $2.78/W installed, no federal credit. Dollars are nominal. Change any of it in the calculator, or compare every utility in Are solar panels worth it in Virginia?

Run it with your bill

9.1 kW

System size

$25,298

Est. cost

$2,073

Year-1 savings

11.2 yrs

Break-even

$62,041

25-yr savings

$36,743

Net benefit

undiscounted

Utility

Electric utilities serving Loudoun County

UtilityTypeAvg price ¢/kWhAvg kWh / monthData year
Dominion EnergyInvestor-owned utility15.201,0382025*

Questions

Questions about solar in South Riding

How much electricity does a solar system produce in South Riding?
About 1,371 kWh per year for every kilowatt of panels on a south-facing roof, according to NREL's PVWatts. An 8 kW system would make roughly 10,968 kWh a year. East- or west-facing roofs make less; the calculator applies those factors.
Who is the electric utility in South Riding?
Dominion Energy serves South Riding, per EIA's service-territory data. Dominion's 2025 average residential price was 15.20¢ per kWh.
Is solar worth it in South Riding?
For an average Dominion home (1,038 kWh a month), the default assumptions give a 9.1 kW system costing about $25,298 with a break-even around 11.2 years and $36,743 net benefit (nominal) over 25 years. Your bill, roof and shade change that; the calculator lets you enter them. The statewide picture is in “Is solar worth it in Virginia?”.
Where does the sun data come from?
NREL PVWatts v8 (8.5.0), using the 1129755.csv typical-year weather dataset for grid cell 1129755, about 2 km from the town center. Inputs: 1 kW DC, fixed roof mount, 180° azimuth, 25° tilt, 14% system losses. Typical-year data doesn't change year to year.

Solar production in towns near South Riding

Sources: NREL PVWatts v8 (8.5.0, typical-year weather); EIA Form 861 2025 utility data and service territories; U.S. Census Bureau place coordinates. Formulas and assumptions on the methodology page.