Four Years Off the Generator: A High-Desert Cabin in Colorado

The Mercers bought 40 acres at 8,100 feet with a cabin, a dry well casing and no utility service within two miles. For two seasons they lived on a 5 kW gas generator, running it four hours a night and hauling fuel eleven miles each way.

High desert is a deceptively good solar site. The irradiance is excellent nine months of the year, but January brings short days and long cold snaps, and their loads were the wrong shape — a well pump that wanted a hard surge and a chest freezer that ran all night.

We spent a weekend with them building a load profile, then Rob redesigned around it: a bigger array than the calculators suggested, storage sized for three cloudy days instead of one, and a pump moved onto its own daytime schedule so it never competes with the evening battery draw.

The well was the piece everyone told them to skip. Instead of pressurizing on demand, the solar pump fills 1,700 gallons of storage during the day and the house pulls from a small pressure pump running on stored power. It cut their pump energy by more than half.

What we'd do differently

• Move the biggest loads to solar noon before buying more storage.
• Size for the worst month, not the average — three days of autonomy in January cost less than the generator would have over five years.
• A generator input on the inverter is worth having even if you never plug one in.
• Bury the water line deeper than the local code minimum. They redug 60 feet in year two.