Solar for vacation and short-term rentals

Owners are often surprised by how much a rental uses. Guests run the hot tub continuously, leave the mini-split on with the deck door open, turn every light on and drive an EV they need to charge. A mountain STR with a hot tub can run 1,200–2,000 kWh a month in winter, and a Front Range townhome used every weekend isn’t far behind a full-time household. On Xcel’s time-of-use schedule, guest dinner hour lands squarely in the 5–9 pm on-peak window, at roughly 2.7× the off-peak rate.

You can’t manage guests’ behavior, and smart thermostats only go so far. What you can manage is the cost per kilowatt-hour. A solar system sized to the rental’s real annual use turns most of that bill into a fixed asset cost you control, and one that doesn’t rise when the utility files its next rate case.

STR usage is lumpier than a home’s: full weeks in ski season and summer, empty stretches in April and November. Solar production is steady across the year with a winter dip, so we size to annual totals and let net metering smooth it. In Xcel territory, surplus credits carry forward and cover the busy months; in co-op territory like Holy Cross or Mountain Parks, annual true-up at a lower rate means we size closer to consumption and don’t overbuild.

A hot-tub rental in a mountain town often lands at 8–12 kW. A Denver-area STR without a tub is more like 5–8 kW. Roof orientation and snow decide whether that fits on the house or needs a ground mount, and mountain-town HOAs and design review boards have aesthetic rules that Colorado’s solar-access law (C.R.S. 38-30-168) limits but doesn’t eliminate.

Mountain-town outages happen in the worst weeks: heavy snow, wind, and increasingly wildfire safety shutoffs, which Xcel has run in late 2025 and 2026. A dark, cold rental with no Wi-Fi is a guest-service failure you’ll refund. A Powerwall 3 or SigenStor with a backup-loads panel keeps the furnace or boiler controls, the fridge, lights, the router and the garage door running through a day-long outage and recharges from the roof.

The hot tub is the one thing we usually leave off backup: a 4–6 kW heater plus pump would flatten a single battery in a couple of hours. Guests can live without the tub for an evening; they can’t live without heat. Remote monitoring through the battery app tells you the rental’s status from wherever you are, which is more than the guests will.

Colorado exempts residential batteries from state sales tax through 2032 and offers a 10% state income-tax credit on battery purchases for tax years through 2026, as of September 2026. Whether those apply to a rental property depends on how it’s held and used; ask your CPA.

STR licensing doesn’t affect solar. The permit for the array is a standard electrical and building permit with the local jurisdiction, and the interconnection is with the utility on the existing meter. We don’t need to know or change your STR license status, and solar doesn’t change it either. The rental keeps a single meter; there’s no need to separate guest and owner usage unless you occupy part of the property and want to.

The tax question is real and we won’t answer it for you. The federal residential credit (§25D) ended for systems placed in service after December 31, 2025, so there’s no residential path there as of September 2026. A property used substantially as a business may be eligible for the commercial §48E credit and bonus depreciation, but a mixed-use STR — one you also occupy part of the year — sits in a gray area that depends on your usage split and how the property is held. That is a CPA conversation, and it can change the payback meaningfully.