Thursday, November 24, 2011

Freezerator Update

Have everything now for the system with the exception of the inverter and battery. The freezer went on sale just after I made the last post and I got it for just over $100.00 off the original price of $499.99. Got the solar panel from ebay along with the updated thermostat. The charge controller is a cheaper unit from Harbor Freight but does the job.

The freezer worked great as a freezer and after putting in the new thermostat, it appears to work great as a refrigerator as well. According to my kill-a-watt meter it draws just under 8 amps for a few seconds at startup and then drops to 1.2 amps. It only runs about 5-6 minutes each hour and after running it for
24 hours it pulled 150 watts of power. I reset the meter and ran it for a second day with the same results.

So what does all this mean? Well if you were to use this on the grid for your normal refrigerator you'd have 14.8 cubic feet of cold storage at the cost of about 96 cents per month. More importantly it means that running it off grid will mean no monthly bill at all. Is the overall cost of the parts to run it off grid cheaper than running it on the grid if you have that option?

The solar panel, inverter, charger controller, and battery cost $372.00. Adding in for the battery box, cabling, and a diy panel mount we can round that up to $400.00. With a monthly cost of $0.96 to run it on grid, it would take almost 35 years to get to the profitable point. However, with replacing the battery every 5 years that's another $600.00 added in so in reality, you'll never get to the point of it being cheaper to run on solar. In fact it'll eventually cost you more.

The real weak point in the entire system is the batteries. Until they solve the battery issues, solar will always be more expensive. Come up with a super capacitor that will hold enough stored energy  to last a few days to cover cloudy days and make it the same cost (or less) than a battery and you've got it made.

The key for us will be to continue to place money in a utility fund each month that we'll be able to pull from when we need new batteries or need to replace water pipes, repair tanks, etc. We won't have to pay the crazy up front costs, and if we have to skip a month of the bill, it's no big deal and nothing gets shut off.

I just see this as one step closer to us getting there......

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