Quote:
Originally Posted by dablack
[snip]1. To save on battery wear, can't I just flip the breaker off at night. If I do it before I go to bed and then turn the breaker back on when the sun is shining, as long as the doors aren't openned too many times, the stuff in the fridges and freezer should stay very cool/frozen. Basically, they wouldn't have power for maybe 12 hours. [/snip]
|
Don't do this! You can get away with losing power to your fridge for 12 hours once in awhile, such as when you come across a power outage but they aren't nearly as well insulated as they need to be for you to get away with this daily. Your refrigerated goods, especially milk last longer the colder they are. I managed to keep standard milk bought from the store and opened the day I bought it for almost 6 weeks when my refrigerator was on the edge of freezing it. With the temperature set to high 30's, I'm lucky to get even its standard shelf life 'sell by' date out of the milk.
Also if your refrigerator goes into a defrost cycle(they do this more often than you think!) and your 12 hour period starts before it has recovered back to temperature after, you'll have spoiled food well before the 12 hours is up.
With my defrost cycle disabled and the house kept at my winter temperature, my fridge uses about 1kwh per day if I never open the door during that day. I'd figure you want some wiggle room. Also don't forget you'll get a couple cloudy days in a row, you really need something automatic to switch back to the grid when your battery pack gets low or you'll be throwing away food if you make a mistake on sun estimates or how much battery you thought you had left. If you want to treat your batteries nicely(especially if going lead-acid) you need to size the system for very shallow cycles and plan for the cloudy days, also plan for the days you actually open and use the fridge, hot days of the year, and the ~300wh defrost cycles. I'd seriously consider oversizing to figure 2kwh per day unless you've got better than just energy star type stuff. You'll be spending more money on lead-acid and the solar PV modules than you'll probably ever save by running the fridge. You'd probably want to make the system big enough to power other things and then on days that aren't so sunny, scale it back down to the fridge.
I've considered going direct solar myself using a 1.2kw solar setup using 4 96 cell modules of the appropriate voltage for a ~48v LiFePO4 pack in parallel but decided to specifically exclude the fridge if I didn't have an automatic way of pushing it back onto the grid when my pack was low. I decided that life would be easier and I'd get more out of the system and the money spent going to solar by going the grid-tied route. 3.3kw grid-tied setup going on my roof this year.