Energy Efficient 120 VAC Fridges vs Sunfrost DC Fridge

Re: Energy Efficient 120 VAC Fridges vs Sunfrost DC Fridge

Some notes on running a standard refrigerator off-grid in Canada from someone who has been doing it for the past twelve years now.

1). For the cost of the Sunfrost you can build up the solar power system to something capable of running anything you throw at it.

2). Even an inefficient refrigerator can be started off a 2kW or larger sine inverter. Any Outback will do it without so much as a blip. Under 2kW it becomes a question of how good the inverter and wiring are.

3). "Most efficient" isn't going to buy you much advantage as the real amount of energy used will be quite different from the lab test results. Expect in the neighbourhood of 1.2kW hours per day. That's what most of the decent units I tested would use under typical conditions. The 980 Watt hours per day you list isn't much different than this.

4). It is not hard to supply the needed power off-grid except in Winter when we just plain run out of sun up here (yesterday: 7 hours 46 minutes total daylight, less time it spent hiding behind mountains).

5). Never mind the standby mode of the inverter. Most of the day it will need to be on to run other things, so that leaves maybe 12 hours of operating in standby at night. During that time the refrigerator will be on approximately 1/3 of the time anyway. Actual inverter off time in a 24 hour period: 4 hours, a savings of 80 Watt hours. Big deal. What is more any refrigerator with fancy electronic controls will get screwed up with the power shut off and will have to start over every time it comes back on. Plan the system for constant power.

Up until this past year I ran with only 700 Watts of panels on my 232 Amp hour 24 Volt system. It worked fine for everything. The main reason I installed the system was to ditch the propane back in 2002 and it was well worth it for the extra 'frige space and lower operating cost (a tank of 20 lbs. now lasts a month instead of a week). The added value of electricity for everything else including water pump, septic system, and satellite Internet access has been well worth it.

This past year I added 520 Watts of panels to start charging earlier in the day. I now have plenty of daylight power and could increase my battery capacity for more nighttime power (as yet not required). Batteries are still fine though (5 years old), so have no intention of replacing them.

You've got 2kW of PV. That should be enough for 320 Amp hours @ 48 Volts which is more than double what I've got. You're looking at 6kW hours AC stored power there @ 50% DOD. Should be no trouble running a refrigerator. Except in Winter. Understand that in Winter the generator will be required.