Cooler farm stands: building an off-grid solar system

The system includes a fridge powered by solar panels and a portable battery generator. During sunny hours, the solar panels power the refrigerator while also charging the batteries, providing enough energy storage to keep the fridge running overnight and through cloudy weather.

To make the entire system accessible to a novice, the team chose components that don’t require previous knowledge of solar systems or electric wiring, meaning they can be set up quickly and easily.

Abazs, who also runs an off-grid farm in northern Minnesota, says, “Off-grid solar and battery systems can power anything from small appliances to an industrial facility. The key is choosing the right components for your needs so you don’t overspend.”

Building any off-grid system means balancing cost, storage capacity, and power output. Deciding on a refrigerator was the first step, because its load (the energy it uses) will dictate the rest of the equipment.

The team's primary challenge was balancing how large of a cooler was possible before running out of room for solar panels on the roof.

Produce is displayed through glass doors on the cooler. (Photo Credit University of Minnesota Extension)

They also wanted to use a cooler with glass doors. This was important to the farmers because it would allow customers to view products, but from an energy standpoint this created a challenge. Glass-front coolers lose much more heat than solid-door models, so the solar system had to be larger to provide the additional power needed to keep the cooler cold.

Kennerhed worked extensively on the research and project design. This was Kennerhed’s first time working on a small, self-sufficient solar project.

When testing various fridges, Kennerhed was surprised by the variety of options. “The numbers almost felt too good to be true — the battery can be really small if an efficient fridge is used!”

Kennerhed says that although energy-efficient fridges cost more initially, people will save money in the long run by buying smaller batteries and fewer solar panels. 

Considering the size of the farm stand’s roof and the power needed for the fridge, the team weighed the factors.

They needed a system that had consistent power. A dead battery could mean spoiled meat or eggs, which could hurt a farm’s profit. To prevent this, the team sized the battery system to keep the cooler running through three days of sunless weather.

Battery generators can have built-in or add-on features to track energy use and production. Paige recommends using these features to track real world energy production and use. Tracking this data allows farmers to predict energy requirements for specific timeframes, which can inform future decisions, such as setting up a new system or downsizing the current one if power generation exceeds actual needs.

Having chosen a relatively inexpensive refrigerator paired with a battery to last three days, the team could then pick out solar panels.

Solar panels come in many sizes and wattages, but how much energy collected per square foot is fairly consistent. Small portable or foldable panels are an attractive option and are often sold in kits, but many battery generators also work with full sized solar panels. These ‘normal’ or ‘contractor’ labeled panels tend to be cheaper and produce more power.

Solar panels on top of the farm stand roof.
 

“The first set of solar panels we ordered were mislabeled,” says Paige who received panels with incorrect wattage labeling that stated they were 400W - yet performing at 200W. Paige worked with Abazs to find the right equipment from a local solar installer.

Setting up solar-powered, off-grid refrigeration takes upfront investment. The entire ready-to-use system costs between $10,000 and $13,000, covering both the structure and the solar equipment. Despite the estimated costs, Paige says that a well attended farm stand may be able to generate that amount of income in a season or two.

Because the solar design is flexible and modular, growers can start small and expand later.

Resources are available on the RSDP website for growers interested in learning how to size their equipment and build a farm stand shed. Looking forward, they are planning to release designs for a mobile farm stand on wheels, as well as additional resources to assist planning for different sized refrigerators.

Special thanks to Farm at the Arb at the Minnesota Landscape Arboretum for hosting the Solar Farm Stand and supporting the project as a living demonstration site. Growers and visitors are invited to see the prototype in person at Farm at the Arb during the 2026 and 2027 growing seasons.