Sunday, May 3, 2015

Tesla Battery Powered home. Payback time.

Tesla has announced a big battery, big enough to run your house overnight, for $3000.  Right now, my electric bill is $100 a month, so it would take 30 months, call it three years, to pay off the battery.  And that's just the battery.  To live off-grid, I need solar panels or a windmill to charge the battery, and some fairly heavy duty electronics to regulate the charging and convert DC into AC.   Let's guess another $3000 before I am off grid all the way and have reduced my electric bill to zero.  It will take 60 months, five years, before I recover my costs, and then I am ahead $100 a month.  I could invest $6000 in the stock market, and with 6% per year, that oughta be worth $8029 after five years.
   You know, that battery is almost making economic sense. 
   I could cut my electricity use a lot by putting in a propane or natural gas tank, and buying new gas appliances, stove, water heater, refrigerator.  Maybe $2000 for all that.  Plus who knows how much for propane.  Wouldn't help my electric bill much since half the bill is a fixed connection charge, but it might reduce the size and hence the cost of the battery I need to get thru a winter night.  The battery HAS to keep the oil burner running so my pipes (and I) don't freeze before dawn.  Dark lasts 14-15 hours in winter around here.  The oil burner uses maybe 5 kilowatt hours over the night.  The battery is advertised to be good for 7 kilowatt hours.  That leaves 2 kilowatt hours for lights, TV, web surfing, and the like. 

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