Adding a freezer to your off the grid home might be too much of a power hog but you might be surprised how efficient today’s freezers are. Selecting an efficient freezer is much like selecting the most efficient refrigerator.
There are essentially two types of freezers available at your local appliance store:
- Chest freezer
- Upright freezer
In almost all cases the chest type freezer will be more efficient than the upright freezer.
Cold air is heavy compared to warm room air such as in your kitchen.
When you open a chest freezer, the heavy cold air stays in the freezer and doesn’t allow warm air in.
This important as you will likely open your freezer a few times a day.
Any warm air allowed in your freezer will have to be cooled.
When you open an upright freezer, the majority of the cold air falls out the door and to the floor. Any cold air that falls out will be replaced with room air that has to be cooled.
Every time you open any freezer, the warm air that enters the freezer will have moisture in it. The moisture will condense inside the freezer and immediately freeze causing a frost build up. Frost is a great insulator that makes it harder for the cold to leave your freezer’s evaporator and cool your food.
The upright freezer will have much more frost buildup than the chest freezer due to the fact that more air is exchanged.
Even if you find an upright freezer and chest freezer that have the same ratings, the upright will consume more electricity.
Almost all the standard freezers are made by only 3 companies in the world:
- W.C. Wood (in Canada) – Amana, Magic Chef, Whirlpool, Danby, Maytag
- Electrolux (in USA) – Frigidaire, Gibson, GE, Kenmore
- Haier (in China) – GE, Kenmore, Amana, Maytag
Spending more money for your freezer to get a certain brand does not make much sense anymore.
Sundanzer 12/24 Volt DC Freezer
The exception to this is Sundanzer. Sundanzer makes a beautiful eight cubic foot (8 cu ft) DC chest freezer that only uses 140 kWh per year. They operate on 12 or 24 volts and are quite reliable. If this is big enough for your family, it is likely worth looking at.
What to look for when purchasing a freezer?
Manual or Auto Defrost – Auto defrost uses electric elements to reduce frost build up on the inside of your freezer. The extra convenience is not worth the extra 25-30% power consumption.
High Temperature Alarm – Some higher end freezers have a computer operated alarm that will warn you of melting conditions. They could have accomplished this with a thermostat and a relay but instead chose to make it a phantom load that can waste power. If you are off the grid, find a unit without this feature.
How to Compare Power Consumption of Different Freezers
Buying an efficient freezer is as easy as going to your local appliance store or the internet and looking at the Energy Guide ratings.
If you live off the grid or are making a backup power system for your home, look for the freezer with the least bells and whistles that uses the least amount of energy.
Don’t let the label fool you.
You will not be able to operate the freezer to the left for $67 per year.
If you use solar energy, expect a kWh to cost you up to $0.50 or $315 per year.
If you use a gas or diesel generator a kWh will cost $2.00 to $4.00 or $1260 to $2520 per year.
You should be able to find a chest freezer that will meet your needs that uses about 1 kWh per day or 365 kWh per year.
A freezer like this (365 kWh per year) will require about 1000 watts of solar if you live in the northern US or Canada.
Those fortunate enough to live in the south should be able to operate a freezer with 500 to 600 watts of solar modules.