Efficient Refrigeration

Last Spring I visited two of the major retail renewable energy suppliers, Real Goods and Alternative Energy Engineering (AEE), both located in California. I have always felt their catalogs emphasized some renewable energy products over others and failed to include some products entirely and my visit confirmed this feeling.

For example, neither store had a Vestfrost refrigerator on the floor and when I asked I was told at both places "Theyíre not as efficient as they claim to be, the Sunfrost is better."

In their catalogues, as well as in Jade Mountainís catalogue, the Sunfrost is always touted as the most efficient and the one that will "save you money in the long run". While the Sunfrost may very well be more efficient than the Vestfrost I wanted to find out if it really provided the best value.

The Vestfrost is a 12 cu. ft. refrigerator/freezer that runs on 120 VAC power and costs $995. The equivalent AC powered 12 cu ft Sunfrost refrigerator/freezer, on the other hand, costs $2045 in the latest Alternative Energy Engineering (AEE) catalog. Neither price includes taxes or shipping.

When included in a renewable energy system both will require a sufficient charge from (for example) PV panels to operate and the cost of that extra power must also be considered in the overall cost of operation of the units.

This is where my research got interesting. Using the information available from my system meters I was able to determine that our Vestfrost actually uses about 1200 watt-hours per day not the 880 watt-hours claimed in the marketing literature.

To operate the Vestfrost you need to include enough panels in your system to provide 1200 watt-hours of power in a day. Assuming 5 hours of full sun a day that equates to 240 watts of panels (1200/5). Though the cost of PV panels varies somewhat a good rule of thumb is to figure the cost at $6/watt of panel output. This means that the Vestfrost will require $1440 worth of panel output to operate. This makes the total cost of buying and operating a Vestfrost in a renewable energy system $2435.

The AC Sunfrost, on the other hand, claims to use only 590 watt-hours of power in a day. I have not been able to test a Sunfrost for actual usage. Also remember the power consumption of any refrigerator will vary depending on how it is used, and these figures are used for comparison purposes only.

Even so, to calculate the actual value of the Sunfrost (based on its rated consumption) you must also consider the cost of the PV to operate it. This works out to 118 watts of panels or $708 worth of panel output. (590 watt-hours/5 hours x $6/watt). Added to the cost of the unit this makes the total cost of operation $2753, or $318 more than the Vestfrost. A DC powered Sunfrost is a bit more expensive, even though it uses slightly less energy, because of its higher initial cost ($2145 in the AEE catalog).

The Vestfrost is less expensive whether you are designing and installing a new system or adding to an existing system. Letís say you design your system with the Sunfrost in mind, calculating your cost of PV panels based on the Sunfrost consumption. It would still be worth buying the Vestfrost on cost alone even if you have to increase the number of panels in your system to accommodate it. Since you have already considered the Sunfrost power consumption in your array size you need only spend an additional $792 for panels for the Vestfrost. This would bring the total cost to $1787, or $258 less than the $2045 cost of the Sunfrost.

These are the figures you, as a customer, never seem to get from the catalog companies. They are telling the truth when they say the Sunfrost is the most efficient. But are they really serving the needs of the customers when they say it is the best value? It also bothers me that the American distributor for the Danish-made Vestfrost chooses to misrepresent the power consumption of their product. The cost to install and operate it is still competitive with the Sunfrost so why misrepresent it?

Iím certainly not suggesting the Sunfrost is not a good refrigerator. Many people might prefer it to the Vestfrost for a number of other perfectly valid reasons that would negate the $300 difference. For example, the Vestfrost is taller than a standard refrigerator, about 6í6", which may be too tall for some folks. Itís height also makes it impossible for it to fit in standard refrigerator space in existing kitchens or under upper kitchen cabinets. The Sunfrost is also American made, which makes a considerable difference for some people.

This industry is still very much in the fledgling stage and needs to be as inclusive as possible of a wide variety of approaches to efficiency and conservation. A fair and accurate representation of the features and actual costs to the customer is a way to build trust. When the products and technologies of this industry are fairly represented it will be easier to develop the concept of renewable energy as a viable alternative to grid-power. Including as wide a variety of products as possible will also help strengthen the industry and allow the different manufacturersí products to stand or fall on their merits.

This bias exists with products other than just refrigerators. In the next column Iíll talk about how the marketing of renewable energy products has resulted in The Great Inverter War.

All Contents © 1998
Wagonmaker Press
Thomas W. Elliot


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