Portable solar powered fridge goes off-the-grid
By Paul Ridden
July 15, 2009
A fridge that positively thrives in direct sunlight might seem a bit of a strange idea, but if you find yourself in a baking hot country where keeping your medical supplies cool and fresh could mean the difference between life and death, or you just want to sell some chilled refreshments to passers-by, then you need a portable, stand-alone chill solution. Industrial Insulation Systems (IIS) has developed a solar powered fridge/freezer which can be tailored to meet the needs of these off-the-grid scenarios.
The custom, made to order IIS solution will maintain temperatures as cold as -5F (-20C) for at least 24 hours between charge, but with the (up to) 400 amp hr battery capacity and the solar panels working in harmony and regular exposure to sunlight, you should be able to go completely off-grid indefinitely.
Gizmag asked VP of Corporate Accounts Jason Luedtke what customers could realistically expect from the system and what would happen if extended periods poor light were experienced. This is what he had to say: "Our initial goal was to create a unit that would maintain the power source to the fridge/freezer for three full days with no sun exposure. That was our goal, the clouds come out you get a three day buffer. Our prototype testing proved that the unit maintained adequate power to hold temperature for nine days before we drifted out of proper temp range. We considered this a success.... but each unit (based on size/therefore power draw) and ambient temperature will have slightly varying results. Ambient temp during the above mentioned test was on average +/-77F. The batteries are a crucial element even during consistent full sun, both elements (panel/batts) must work in a regulated balance, if so and there is consistent sun then the system is nearly perpetual."
Putting it all together
According to a company brochure, "Solar technology delivers a long-term solution for freezing and refrigerating on or off the grid." As you might expect, this particular solution will work with any refrigeration unit in the IIS range but if you already have your own low voltage (DC) fridge and would rather not cough up any extra cash for a new one, don't worry as you can just buy the solar kit and fit it to that.
With the fridge chosen you'll then need to decide how it is going to be housed. Will you need a trolley with castors for portability? Or would you like it stationary, outside in your yard or in your garage perhaps? On your boat or yacht? Or something else entirely? Armed with this information IIS will then help you to work out your exact power draw. The solar panel canopy works in balance with batteries to make sure that your chosen unit doesn't run out of juice so it's important to get those sums right.
Once those basics are in place it's time to customize. If you want your fridge kept out of the sun then you'll need extra long cables to link it up with the solar canopy, which can then be optimally placed to get the most direct sunlight. You might need extra storage space on your trolley if you intend to use your unit for street vending. You might also need some AC outlets. All these options and more are taken care of in this stage.
Or as Jason puts it, "pick the model of fridge/freezer, tell us how to mount it, then how to power it, then customize it to fit your optimal needs."
See the IIS website for further info.