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Things to consider when buying a Solar Refrigerator or High Energy Efficient Refrigerator. |
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Considering
a Sun Frost refrigerator then please read the February 1994 issue of
Consumers Reports. According
to Consumer Reports, Sun Frost energy consumption figures are unrealistic. Comparison
Chart: 1. Compressors and condenser coils and fans are mounted on the bottom.
2.
Compressors and condensing coil are fan cooled. This improves cooling efficiency in hot climates and lowers
energy consumption. This
feature is important for environmentally friendly R134a refrigerant. 3.
Condenser uses all copper tubes and fins to resist corrosion due to
humidity and cleaning chemicals. There
is easy access for vacuuming dust off the condenser to keep cooling
efficiency high. 4.
Available in right and left hand hinges. 5.
Door in mounted similar to a conventional refrigerator door. No
additional clearance around the refrigerator is required for door opening. 6.
Designer door panels. 7.
Molded plastic construction in comparison to wood and Formica. 8.
4 inches of polyurethane insulation for the model SR-16. 9.
Efficient Danfoss model 35 compressors. |
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Why
doesn’t Polar publish its energy consumption figures? As
soon as we can create a chart or computer program that can provide
meaningful energy numbers we will do so.
Please consider that the refrigerator/freezer’s energy
consumption is effected by the amount of ice produced, the internal
thermostat settings for the refrigerator and freezer sections, the amount
of warm food and beverage placed in the unit each day, the type of food
and food packaging, ambient air temperatures and humidity, and the number
of door openings. All these
factors vary greatly from house to house.
Previously when we published the energy consumption at a given set
of conditions, “solar engineers” and consumers incorrectly projected
performance and typically undersized their solar array.
The
second reason is that the solar industry has been plagued with
manufactures making incredible or misleading claims.
Since there is no independent agency testing and regulating the
industry, the honest manufactures and customers get hurt.
For example, see the February 1994 Consumer Reports article on Sun
Frost. Sun Frost claimed
performance of 374 kWh at refrigerator temperature of 38 F and 15 F
freezer; Consumer Reports measured 495 kWh for the same conditions.
But the important point is that household freezers are rated at 5 F
and not 15 F. The colder the
freezer or refrigerator the more energy it uses (also, the larger the unit
the more energy its uses). Consumer
Reports adjusted the Sun Frost down to 5 F and the energy consumption
increased to 710 kWh per year. A larger conventional AC
refrigerator/freezer in the report drew 825 kWh per year and it was $2,000
lower in cost. In
a solar system if you undersize the number of solar panels the
refrigerator stops working. In
an AC home connected to the utility grid, the owner simply gets a higher
electrical bill. In a solar
hybrid system using propane or a diesel generator will simply require more
fuel. |
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Trying
to determine weather to buy a DC, a conventional AC, or our energy
efficient AC refrigerator? AC
or DC Refrigerator/Freezer? Some
pointers for your consideration: 1.
At some point in time your inverter may fail.
Operating directly off the battery provides continued refrigeration
while the inverter is being serviced. 2.
Most of the popular inverters presently used do not produce true
sine waves. The AC compressor
motor loses between 8 to 15% when its not operated on a sine wave. 3.
There is approx. a 5 to 10% energy loss converting from DC into AC. 4.
The AC compressor motor will have a starting current surge, and
this will impact the amount of power available from your inverter to power
other appliances. 5.
Some inverters when they fail or become overloaded will output a
low voltage that will damage the AC compressor motor. The
most important home appliances are lights and refrigeration and any
medical devices, which are best, operated directly off the battery
(through a fuse of course). For
lights I would using the new fluorescent tubes using high efficiency DC
ballasts. If
your are in a solar home and prefer to have an AC refrigerator then we
suggest that you carefully evaluate the cost difference between purchasing
a conventional AC appliance and adding more modules, verses Polar’s more
expensive AC unit using less modules.
In some areas like California it may make more sense to buy a
conventional AC refrigerator. In
other areas like the Puget Sound, the lower insolation favors our product. |
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If
you are concerned about Y2K: I
would buy our chest type DC refrigerator/freezer and place it in the
garage. I would install two
75 peak watt solar panels for operation as a refrigerator operation only
mode or three 75 peak watt modules operating as a freezer.
Two quality deep cycle batteries should work fine in this
application. Or Use a good battery charger in place of the solar panels. If the event does occur I would use the AC or DC generator to charge the battery. It will not be practical to run a small AC generator to power your AC refrigerator. I can not image using a portable or RV type generator 10 or 24 hours a day; it simply will not last very long before requiring lots of service. |