Could we make a practical solar fridge?

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Discussion Overview

The discussion revolves around the feasibility of creating a practical solar-powered refrigerator, particularly for off-grid living. Participants explore various designs, components, and energy storage methods, focusing on refrigeration technology and solar energy applications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant suggests using a chest freezer divided into two compartments, with a variable speed BLDC compressor powered directly by solar panels, aiming to store enough energy to keep food cold for several days without sunlight.
  • Another participant questions whether adding antifreeze to the water for thermal storage would negate the benefits of the latent heat of freezing.
  • A different approach is proposed involving a shell structure around the freezer to hold ice packs, which could provide a more uniform temperature and allow for expansion of the freezing liquid.
  • There is a suggestion to consider using a nonimaging solar heat collector to power an absorption refrigerator, along with the idea of incorporating phase change materials for thermal mass.
  • One participant emphasizes the importance of making the design user-friendly for maintenance and repair, advocating for a system that allows users to manage thermal storage with easily accessible materials.
  • Concerns are raised about the practicality of swapping out the compressor in modern freezers, highlighting the need for special equipment to handle refrigerants.

Areas of Agreement / Disagreement

Participants express a variety of ideas and approaches without reaching a consensus. Multiple competing views on design and functionality remain, particularly regarding the use of different materials and methods for thermal storage and energy efficiency.

Contextual Notes

Participants note limitations related to the assumptions about energy storage capacity, the efficiency of different compressor types, and the practicality of DIY modifications to existing refrigeration systems.

Who May Find This Useful

This discussion may be of interest to engineers, DIY enthusiasts, and individuals living off-grid who are exploring sustainable refrigeration solutions.

  • #31
The Bill said:
Another option is to use a nonimaging solar heat collector (maybe something similar to the evacuated glass tube collectors on solar water heaters) to power an absorption refrigerator.
I think that could be a good way to go. Absorption fridges were popular for camping because they could use gas, 12V or mains, depending on the circumstances.

But what about using a totally thermoelectric (Seebec / Peltier) system, with a solar furnace beamed onto a large area of Peltier panels (pretty cheap and modular) and some thick cable, routed round the house, to similar panels in the fridge?

The temperature of the hot source should be as high as possible, consistent with the panel not getting over-cooked (<320C or less for cheap units). That could be taken care of with a bimetal strip to defocus or deflect the incident sunlight. Efficiency could be a problem but hot weather would supply more cooling than cold - which is the right way round.

Any system with interrupted power supply could use water / ice as a thermal store but, in a static situation, a water tank wouldn't be a problem.
 
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