Fairfax County Dominion

Solar panels in Annandale, Virginia: 1,420 kWh per kW per year

A south-facing kilowatt of panels in Annandale makes about 1,420 kWh a year, 4% above the Virginia median. Power here comes from Dominion Energy at 15.20¢ per kWh (2025 average).

1,420

kWh / kW / year

PVWatts, south-facing

5.00

Peak sun hours / day

annual average irradiance

11,360

kWh / yr from 8 kW

a common home system

15.20¢

Dominion price

2025 residential avg

NREL PVWatts v8, 1 kW DC, fixed roof mount, azimuth 180°, tilt 25°, 14% losses. Jul makes about 1.7× Dec.

Seasonality

Monthly solar production in Annandale

Virginia net metering carries excess credits forward for 12 months, so Jul'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: 16.2%. Elevation about 101 m. Compare every town on the city list, or see how roof direction, tilt and shade change the number.

Payback in Annandale

Solar cost and payback for an average home in Annandale

Assumes 1,038 kWh a month (≈ $158) at Dominion Energy's 2025 average price, Annandale'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

8.8 kW

System size

$24,464

Est. cost

$2,073

Year-1 savings

10.8 yrs

Break-even

$62,161

25-yr savings

$37,697

Net benefit

undiscounted

Utility

Electric utilities serving Fairfax County

Utility	Type	Avg price ¢/kWh	Avg kWh / month	Data year
Dominion Energy	Investor-owned utility	15.20	1,038	2025*

Questions

Questions about solar in Annandale

How much electricity does a solar system produce in Annandale?

About 1,420 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 11,360 kWh a year. East- or west-facing roofs make less; the calculator applies those factors.

Who is the electric utility in Annandale?

Dominion Energy serves Annandale, per EIA's service-territory data. Dominion's 2025 average residential price was 15.20¢ per kWh.

Is solar worth it in Annandale?

For an average Dominion home (1,038 kWh a month), the default assumptions give a 8.8 kW system costing about $24,464 with a break-even around 10.8 years and $37,697 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 1139880.csv typical-year weather dataset for grid cell 1139880, 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 Annandale

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.