Solar and battery backup for refrigerators and freezers

Grid-tied solar is built to disconnect the moment the utility goes down. That protects the crews repairing the line, and it is required by every Colorado utility’s interconnection agreement. So a house with 8 kW of panels and no battery sits dark on a sunny afternoon just like the neighbors.

A battery changes the arrangement. A transfer switch isolates the house from the grid, the battery becomes the house’s own small grid, and the panels keep charging it as long as the sun is up. The refrigerator never notices the switch-over; it is fast enough that the compressor keeps running.

A modern refrigerator-freezer draws 100–200 W when the compressor runs and cycles maybe a third of the time, so it lands at about 1–2 kWh a day. A chest freezer is better insulated and opens less, so it is closer to 1 kWh a day. Together that is 2–3 kWh a day, and less if you leave the doors closed.

A Powerwall 3 stores 13.5 kWh. An Enphase IQ Battery starts at 10 kWh; a SigenStor starts at 9 kWh and grows in 9 kWh modules. On refrigeration alone, any of those runs a fridge and freezer for four to six days with zero sunshine. Add a furnace blower, lights, a router and phone charging and you are still typically at two or three days, and every clear day — Colorado has about 300 of them — puts most of that back.

The compressor’s startup surge is the only thing to check with small inverters. For a home battery it is trivial; a Powerwall 3 or SigenStor starts a refrigerator, a freezer and a well pump together without complaint.

A closed refrigerator keeps food safe for about four hours; a full chest freezer holds roughly two days if it stays shut. Ordinary storm outages in the metro area rarely last that long. The outages that spoil a freezer are the multi-day ones: a wildfire public safety shutoff, a mountain community’s line down in a snowstorm, or a rural co-op outage after wind.

Xcel has run wildfire safety shutoffs along the Front Range foothills in both December 2025 and 2026, some lasting more than a day, with limited warning. If you live in Evergreen, Conifer, the Boulder foothills or any red-flag-warning zone, a battery is less about convenience and more about not throwing out a freezer.

A refrigerator holding insulin or other temperature-controlled medication is a different category of risk. The energy is the same, but the tolerance for failure is not. We put those circuits on the battery’s backup panel first, and our medical-equipment backup page covers the wider set of devices.

Every fall, hunters across Colorado fill a chest freezer in the garage with an elk or two — a few hundred dollars of tags, a week of effort, and a winter of meals — and a November line outage can take all of it. A freezer in an unheated garage is also easier to keep cold than one in a warm kitchen, which stretches battery runtime further. It is a common reason mountain and rural households ask us about a battery in October.

Most households choose a backup-loads panel: refrigerator, freezer, furnace blower, well pump, a few lights and outlets, the internet router. The battery runs those and ignores the AC, the oven and the dryer. A whole-home setup runs everything and simply needs more battery or a lighter hand during the outage.

First-battery pricing runs roughly $15,500 for a SigenStor, $17,000 for an Enphase IQ Battery and $19,000 for a Powerwall 3, installed. As of September 2026, Colorado exempts residential batteries from state sales tax through 2032 and offers a 10% state income-tax credit on the purchase for tax years through 2026; the federal 30% residential credit ended for systems placed in service after 2025. Confirm with a tax advisor. A battery can go on an existing array from another installer too, though we don’t take over that array’s service.