Solar for electric heat

A Front Range array produces roughly a third to half as much in December as in June: the day is about six hours shorter, the sun sits low enough that a typical roof pitch catches it poorly, and snow can cover the panels for days after a storm. In mountain towns at 8,000–9,000 feet the sun is stronger and the air clearer, which helps, but snow stays on roofs longer and the heating season runs from October to May.

Meanwhile a baseboard or electric-furnace home may draw 2,000–4,000 kWh in a cold month, several times its summer use. A 10 kW array might produce 500–900 kWh in that same month. No amount of rooftop is going to match that in real time. The question is not whether panels cover January directly — they do not — but whether the year balances.

In Xcel and Black Hills territory, Colorado’s net-metering statute, C.R.S. 40-2-124, credits surplus production at retail and carries credits forward month to month, so a large summer surplus offsets winter consumption on the bill. An electric-heat home with enough roof can bank credits from April through October and spend them from November through March. That is the mechanism that makes solar for electric heat possible at all, and it is why these systems get sized larger than the roof’s midsummer output would suggest.

Co-ops and municipal utilities are different. They must offer net metering to at least 10 kW residential under C.R.S. 40-9.5-118, but many settle credits at an annual true-up, sometimes paying surplus at a wholesale or avoided-cost rate well below retail. Mountain co-ops serve many of the state’s electric-heat homes, so this matters a lot: if surplus is bought back cheaply once a year, over-sizing to bank summer credits stops paying. We read the specific utility’s tariff before sizing, and we ask you to verify it with them.

The 10 kW residential threshold also bites. A baseboard home using 15,000–20,000 kWh a year wants a 10–15 kW array, and above 10 kW a co-op may decline or impose different terms. Sometimes the honest design is a 10 kW system that covers most of the year plus a heat pump that shrinks the rest.

Baseboard heaters and electric furnaces are resistance heat: one kilowatt-hour in, one kilowatt-hour of heat out. A cold-climate heat pump moves heat instead of making it and delivers two to three kilowatt-hours of heat per kilowatt-hour of electricity across most of a Colorado winter, with efficiency falling on the coldest nights. Converting a baseboard home to a ducted or ductless heat pump typically cuts the heating electricity by half or more, which cuts the solar array needed by the same fraction.

That is why we say heat pump first. A home that needs 14 kW of panels on baseboard may need 8 kW on a heat pump, and 8 kW fits a normal roof and stays under co-op thresholds. Keep the baseboards as backup for the coldest nights if you like; the heat pump does the bulk of the season. The switching-to-heat-pump page and the electrification calculator size both steps together, and as of September 2026 there are state and utility incentives for heat pumps that change often enough that we do not print amounts — check the current programs.

Take a mountain home using 16,000 kWh a year, mostly winter heat. At Colorado’s roughly 1,300–1,600 kWh per installed kilowatt, covering it fully takes a 10–12 kW array, or about 25–30 panels at 400–440 W — roughly 500–600 square feet of good south-facing roof, which many mountain homes do not have, and a ground mount if they have land. At $2.80–$3.25 per watt, that is roughly $28,000–$39,000 before incentives, and as of September 2026 the 30% federal homeowner credit is gone.

Convert the same home to a cold-climate heat pump and annual use might fall to 8,000–10,000 kWh. Now a 6–7 kW array of 15–18 panels covers it, at roughly $17,000–$23,000, on a roof that exists. The heat pump costs money too, but it is the piece that makes the solar affordable, and it makes the house more comfortable. That ordering — shrink the load, then size the array — is the single most useful thing on this page.

Snow changes the layout. Steeper pitches shed faster, panels near the eave shed before panels near the ridge, and a ground mount can be built steep and clear of drifts. Where the roof is shallow and snow lingers, we size expecting a few lost weeks in midwinter rather than pretending the panels are always clear.

There are electric-heat homes where we say no, or not yet. A north-facing or heavily shaded roof in a valley with no ground-mount space; a co-op that pays surplus at a low annual true-up so summer credits are worth little; a home you plan to sell within a few years and would buy solar with cash. In those cases the returns are thin, and a lease or PPA — where the owner can still claim a federal credit on systems placed in service by the end of 2027 — may be the only version that makes sense, or none may.

The alternatives are not glamorous but they work: insulation and air sealing, which cut a baseboard home’s load more per dollar than anything; a heat pump on its own, with solar later; and, in outage-prone areas, a battery that keeps the furnace blower or a few baseboard circuits running during a shutoff. Homes heating with propane sometimes look at electric heat plus solar as a way off propane deliveries; that can pencil when propane is expensive, and we run it honestly both ways with the electrification calculator.