Ultra-low energy fridge

I just came across this article and thought it was worth sharing:
A fridge that takes only 0.1 kWh a day?

In a nutshell, an off-the-gridder converted a chest freezer into an ultra-efficient refrigerator simply by installing a secondary thermostat which cuts off the motor once the correct temperature is reached.

The downside is that being a chest getting stuff out isn't always easy, but if you want a fridge you can run off solar cells it's worth the hassle.

-Blast

I'm still waiting for my Vestfrost SE255 to be delivered. Excellent article BTW. The simple analogue bang bang controller looks like it could be refined much further. Looks like another another PIC chip project so I can control the temperature of the Freezer and operate it as a Fridge or Freezer if need be from my ongoing solar project without voiding the warranty.

The inverter I have chosen is a WAECO SinePower MSP352/MSP354 which allows the inverter to be switched on and off remotely from the digital thermostat controller, with the possibility of implementing a 3-term temperature control law for tighter set point temperature regulation. The thermostat controller could even chill the fridge even cooler down to 1-2 C during the day when there is plenty of solar energy and draw down less energy during the night time so that the temperature rises slowly up to 5-6C overnight thus saving the lifetime of the battery array by minimizing deep cycling effects. A relay could also be used, so as to switch from the Solar Battery Array/inverter 240V source to mains if the batteries become too discharged.

Thank you. Got it.

I always thought about that!

I wonder how long the stuff will last constantly switching on and off???

Due to the better insulation and design of the freezer it doesn't cycle on and off much. According to the author the compressor only runs 90 seconds per hour.

-Blast

The guy uses hanging or stacking baskets to put his food in. They're really for freezers, so they fit. He puts his most-used stuff in the top baskets and least-used ones in the bottom baskets.

Some look like this: http://stockingthelarder.blogspot.com/2009/04/how-i-organized-my-chest-freezer.html Sometimes you can find them on Craigslist, and you might be able to find them at a place that accepts discarded freezers/refrigerators.

That's a lot of savings for a little bit of inconvenience.

Sue

I saw this a few years ago. Very interesting and worthwhile experiment, from an energy efficiency point of view.

A friend tells me you can order conversion kits online, but I have no info regarding cost or quality.

In a big-trouble scenario, I think super-energy-efficient freezing is what counts the most. Refrigeration is a novelty more than a necessity, except for certain meds. (I.e., take some ice from your freezer and put it in a super-insulated box with today's leftovers.) My 0.02.

If someone wants to try it, perfectly serviceable freezers are free for the taking. They work great, but suck too much juice to keep around. Block of ice in the bottom third, a sealed and thick insulating blanket, and a timer that runs ten minutes every three hours. Boom, it's a chest fridge.

There's no inherent value to a digital thermostat over analog other than precision. If a few degrees either way don't matter - and they won't here - then analog would seem simpler and more efficient.

He never seems to have looked into the insulation properties of his freezer vs. refrigerator. I bet that freezer leaks heat a lot less, and that this accounts for a lot of the efficiency gains.

A neat idea, but it needs a lot of space. I don't have room anywhere indoors for such a thing.

"He never seems to have looked into the insulation properties of his freezer vs. refrigerator. I bet that freezer leaks heat a lot less, and that this accounts for a lot of the efficiency gains."

He used a Vestfrost freezer, which has the rep of being one of the most efficient brands around, using half the power of a regular freezer. I would assume that he took that into consideration when he made his choice.

Sue