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Considerations When Selecting Appliances
for Off-Grid Living:
Refrigerators and Freezers
Conventional Refrigerators and Freezers use electric compressors to
cool and circulate a cooling fluid. This architecture requires a
tremendous amount of electricity. Indeed, electric refrigeration is
often a very large component of an off-grid home's total power budget.
A good idea of the power required can be gained by examining the
required
energy efficiency placard required to be afixed to all
new appliances. The placard will state an estimated dollar cost and
number of kiloWatt hours per Year (kWH/yr) used by the appliance
in a typical application.
To get an estimate of your
refrigerator's energy requirement
for the System Design Worksheet:
- Divide the estimated kiloWatt Hours per year by 365 days/year to
obtain an estimate of required kiloWatt hours per day.
- Multiply this value by 1,000 to get estimated Watt-Hours per Day
- Divide the estimated Watt Hours per Day by 2.4 hours to represent a
10% duty cycle for the refrigerator. This represents the estimated
power requirement, in watts, for the refrigerator when the compressor
is operating.
- Enter into the table the estimated power requirement, and the 2.4
hour per day running time.
This is only a rough estimate, and does not include such intermittent
loads as automatic defrost, ice makers, etc. But this procedure will
yield a pretty good overall estimate of the load your off-grid power
system will have to handle.
Special high-efficiency electric refrigerators are manufactured by
SunFrost.
European brands of Refrigerators and Freezers such as
ConServ
are also very efficient.
Also, the most modern refrigerators are dramatically more efficient
than those of only a few years ago.
Of course, you could also consider a refrigerator or freezer that requires
NO electricity at all! Refrigeration utilizing the
Ammonia
absorption principle requires only a heat source to drive their cooling
cycle. Most of these ammonia-cycle units use natural gas or propane to provide the
neccessary heat source. The required flame is little more than a small
'pilot light' and the units use very little fuel. Most off-grid aplications
would utilize units configured for propane.
With no moving parts, these units are absolutely silent and last
for a very long time.
Current production units are manufactured by
Servel/Dometic,
Frostek and
Crystal Cold.
The Crystal Cold units, in particular, look just like everyday
refrigerators or freezers.
Be aware that some of these propane refrigerators DO require
periodic maintenance. Specifically, the Servel/Dometic units require
cleaning of the burner and related components every six (6) months.
Some disassembly of the unit is required, and an air compressor is
very useful for cleaning the small metering orifice.
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