Solar fridges: running a refrigerator on solar without buying a new one

People mean two different things by a solar fridge: a DC appliance built for 12 or 24 volts, or an ordinary household fridge running inside a solar system. The second is what most homes need, and it does not mean replacing the fridge.

Why a fridge is both an easy and a hard load

Easy, because its daily energy is modest. Hard, because the compressor draws several times its running power for a second or two at start-up. An inverter sized for the average but not the start will trip — which is behind most complaints that an inverter will not run a fridge.

Which is where inverter fridges help

An inverter fridge — a variable-speed compressor — ramps up instead of slamming on, so its inrush is far lower. If you are buying a fridge anyway, that choice shrinks the inverter you need and lowers the daily draw.

Sizing, in three steps

• Read the daily kWh off the appliance's energy label
• Multiply by the days of backup you want to get battery capacity
• Choose an inverter whose surge rating covers the compressor's start, not just its running watts — each inverter page states continuous and peak output

To add the rest of the kitchen to the fridge, work out your own loads in the sizing calculator, open the solar system for an apartment with evening backup power and browse Deye batteries.