Learn: seasons
Do Solar Panels Work in Winter in Northern Virginia?
Yes. A Northern Virginia array keeps producing all winter, just less than in summer. In a PVWatts model of a south-facing Fairfax roof, December produces about 62 percent of what July does, and net metering carries the summer surplus into the winter bills.
Reviewed 2026-09-24
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Answer first
The short answer
Solar panels work in winter. They produce less because the days are shorter and the sun is lower, not because it is cold. A PVWatts model of a south-facing Fairfax roof, a modeled estimate using typical-year weather, puts December at about 62 percent of July's output, and November through February at about 27 percent of the year's production. Dominion's 12-month net metering period credits the extra summer production against winter use.
- Modeled estimate: about 1,378 kWh per installed kW per year for an unshaded south-facing roof at a 30 degree tilt in Fairfax.
- May through August carries about 39 percent of the year; November through February about 27 percent.
- Cold does not hurt panels. Heat lowers output, so a clear winter day is efficient per hour of sun.
- Snow stops production until it slides or melts off. Leave it alone and stay off the roof.
Month by month: what a Northern Virginia array produces
The table below comes from PVWatts, the production model built by the federal lab formerly called NREL, now the National Laboratory of the Rockies. We ran it for Fairfax with one kilowatt of panels facing due south at a 30 degree tilt and the calculator's default 14 percent system losses. The model uses typical-year weather data for the location. These are modeled estimates, not measurements from any one house.
Multiply by your array size to scale it. A 10 kW array is ten times each row. Your own roof will differ with its direction, pitch, and shade, which is why the site visit models your actual roof before we write a number.
| Month | Modeled kWh per kW |
|---|---|
| January | 103 |
| February | 93 |
| March | 125 |
| April | 120 |
| May | 128 |
| June | 133 |
| July | 136 |
| August | 134 |
| September | 116 |
| October | 113 |
| November | 94 |
| December | 84 |
Annual total about 1,378 kWh per kW. Our proposals plan on about 1,250 kWh per kW to allow for real roofs that are not ideal.
Why winter output drops
Two things change in winter: the day is shorter and the sun sits lower in the sky, so its light crosses more atmosphere and strikes the panels at a steeper angle. The same PVWatts run shows the solar energy reaching a tilted Fairfax panel averaging about 3.2 kWh per square meter per day in December against about 6.1 in July. The U.S. Energy Information Administration notes that these seasonal swings grow with distance from the equator.
Cloud cover matters too, but panels still work under clouds. The EIA explains that flat photovoltaic panels use both direct sunlight and the diffuse light scattered by clouds. A gray January day produces less than a clear one, but not zero.
Shade is the winter factor homeowners miss. A tree line or a neighbor's roof that clears the panels in June can shade them for hours in December, when the sun is low. We model shade by month for that reason, and a roof that looks sunny in summer can lose much of its winter production to a single evergreen.
Cold and snow
Cold is not the problem. Solar cells convert light to electricity more efficiently when they are cool, and output falls as panels heat up. A crisp, clear day in January is an efficient day per hour of sunlight. Cold does raise panel voltage, which is why we size inverter inputs to the coldest temperature the site is likely to see. That is an electrical design step, and it is one reason the design belongs with an electrician.
Snow is a pause, not damage. While snow covers the panels, they produce little or nothing. The dark glass and the tilt help snow slide off once the sun hits it.
- Do not climb on the roof or push a ladder against the gutters to clear panels.
- Do not scrape the glass or pour hot water on it.
- Keep walkways and shrubs clear under the eaves. Snow slides off panels in sheets.
- If a panel section stays dark long after the snow is gone, check the monitoring app and call for service.
Net metering is how summer pays for winter
On a monthly bill, a solar home often sends power to the grid in spring and summer and draws more than it makes in December and January. Dominion's net metering program records excess energy you send to the grid as a credit and uses it to offset energy delivered to the house later, over a 12-month net metering period. That is the mechanism that carries June's surplus into January.
Two practical rules follow. First, size the array to your annual use, not your winter use. Dominion caps a system at a size that would not reasonably produce more than 150 percent of expected annual consumption, and anything left over at the end of the 12-month period is paid at a rate well below retail. Second, the month your net metering period starts affects when the credits roll over, so ask about it when the interconnection is filed.
NOVEC customers in the western county run under NOVEC's own net metering terms. We confirm the serving utility from your bill before we size anything.
Winter storms and outages
A grid-tied array shuts off when the grid goes down, in any season. That protects line workers repairing the lines. Dominion's net metering page says it plainly: the only way to power your home from a distributed generation system during an outage is an energy storage system and a transfer switch.
If winter outages are your concern, the answer is a battery on selected circuits, not a bigger array. A whole-home battery integration typically runs $6,000–$15,000+, and on short winter days the battery may not refill fully from the panels, so the circuit list matters more in January than in July.
Straight answers
Questions
- How much less do solar panels produce in winter?
- In a PVWatts model of a south-facing Fairfax roof, December produces about 62 percent of July's output, and November through February together is about 27 percent of the year. These are modeled estimates; your roof's direction and shade change them.
- Should I clear snow off my solar panels?
- No. Stay off the roof, do not scrape the glass, and let the snow slide or melt. Production resumes once the panels clear.
- Do solar panels work on cloudy days?
- Yes, at reduced output. The EIA notes that flat photovoltaic panels use diffuse light scattered by clouds as well as direct sunlight.
- Will my bill go up in winter with solar?
- Your winter bill can rise compared with summer because production drops. Under Dominion net metering, credits banked earlier in the 12-month period offset that winter use.
Next step
See your roof's winter numbers
We model your roof month by month, including winter shade, before we quote. The quote is free.
Solar energy company
AJ Long Electric Solar
AJ Long Electric
7138 Little River Turnpike #305
Annandale, VA 22003
Serving Annandale, Fairfax County, and Northern Virginia.