4 ms·

They have a calculator. Check it out instead of guessing wildly

semi-extrinsic 9y ago
FWIW, I have some colleagues who are researching how to reduce energy usage in buildings. It's a lot harder than you would assume just based on pure math, since you have to take Jevon's paradox [1] and other "psychological" effects into account. I.e. when energy gets cheaper, you use more of it. In my area (same latitude as Anchorage, ~ 65% of the incoming solar energy as in San Francisco), they calculated that solar roof panels on a typical house doesn't break even over a 25 year period, you're still thousands of dollars in the red. Only the "cheap" air-to-air heat pumps (AC in reverse) and solar heating of your hot water give good ROI. What both these have in common is that the purchase and installation cost is much lower than e.g. rooftop solar. [1] https://en.wikipedia.org/wiki/Jevons_paradox https://en.wikipedia.org/wiki/Jevons_paradox
- FeepingCreature 9y ago
  Why would you take those into account? Using more energy doesn't mean it "takes longer to recoup", because now you're getting value in the form of additional energy to use.
  - semi-extrinsic 9y ago
    Are you really getting value? Or are you just not bothering anymore to conserve a resource when it's less expensive to waste it?
    - FeepingCreature 9y ago
      Well, you could argue the same if I double your income, but you spend the increase. Like it or not, demand through consumption is the root source of value in capitalism.
- dogruck 9y ago
  Reminds me of this 2010 New Yorker story about Saul Griffith: http://www.newyorker.com/magazine/2010/05/17/the-inventors-dilemma http://www.newyorker.com/magazine/2010/05/17/the-inventors-d...
  - seltzered_ 9y ago
    Saul did a more recent long now talk on some of the rough numbers for homes: http://longnow.org/seminars/02015/sep/21/infrastructure-and-climate-change/ http://longnow.org/seminars/02015/sep/21/infrastructure-and-...
    - dogruck 9y ago
      Ah, thanks -- hadn't seen that before.
  - deleted 9y ago
    [deleted]
11thEarlOfMar 9y ago
I did the calculation back in May when this article [0] came out and recalled the rough numbers correctly for my home (they changed the calculator on their web site, now only talks about the value of electricity the roof would produce). The quote from the article is: "The average home in the United States is 2,467 square feet. According to Tesla’s handy solar calculator, the new system will set an average homeowner back $51,200 for a 70% solar roof. The company also recommends purchasing the additional, but optional, Powerwall battery to store all that new energy at $7,000, bringing the grand total of installation to $58,200." My roof is much larger than the average (2,750 livable + roof over garage) because mine is a ranch and the average includes 2-story homes which will have much smaller roof area for the same home square footage. So it's quite reasonable to get from an average cost of $58,200 to $75,000 for my specific home. [0] https://www.forbes.com/sites/sleasca/2017/05/16/tesla-solar-roof-cost/ https://www.forbes.com/sites/sleasca/2017/05/16/tesla-solar-...

FWIW, I have some colleagues who are researching how to reduce energy usage in buildings. It's a lot harder than you would assume just based on pure math, since you have to take Jevon's paradox [1] and other "psychological" effects into account. I.e. when energy gets cheaper, you use more of it. In my area (same latitude as Anchorage, ~ 65% of the incoming solar energy as in San Francisco), they calculated that solar roof panels on a typical house doesn't break even over a 25 year period, you're still thousands of dollars in the red. Only the "cheap" air-to-air heat pumps (AC in reverse) and solar heating of your hot water give good ROI. What both these have in common is that the purchase and installation cost is much lower than e.g. rooftop solar. [1] https://en.wikipedia.org/wiki/Jevons_paradox https://en.wikipedia.org/wiki/Jevons_paradox

FeepingCreature 9y ago
Why would you take those into account? Using more energy doesn't mean it "takes longer to recoup", because now you're getting value in the form of additional energy to use.
- semi-extrinsic 9y ago
  Are you really getting value? Or are you just not bothering anymore to conserve a resource when it's less expensive to waste it?
  - FeepingCreature 9y ago
    Well, you could argue the same if I double your income, but you spend the increase. Like it or not, demand through consumption is the root source of value in capitalism.
dogruck 9y ago
Reminds me of this 2010 New Yorker story about Saul Griffith: http://www.newyorker.com/magazine/2010/05/17/the-inventors-dilemma http://www.newyorker.com/magazine/2010/05/17/the-inventors-d...
- seltzered_ 9y ago
  Saul did a more recent long now talk on some of the rough numbers for homes: http://longnow.org/seminars/02015/sep/21/infrastructure-and-climate-change/ http://longnow.org/seminars/02015/sep/21/infrastructure-and-...
  - dogruck 9y ago
    Ah, thanks -- hadn't seen that before.
- deleted 9y ago
  [deleted]

11thEarlOfMar 9y ago

I did the calculation back in May when this article [0] came out and recalled the rough numbers correctly for my home (they changed the calculator on their web site, now only talks about the value of electricity the roof would produce). The quote from the article is: "The average home in the United States is 2,467 square feet. According to Tesla’s handy solar calculator, the new system will set an average homeowner back $51,200 for a 70% solar roof. The company also recommends purchasing the additional, but optional, Powerwall battery to store all that new energy at $7,000, bringing the grand total of installation to $58,200." My roof is much larger than the average (2,750 livable + roof over garage) because mine is a ranch and the average includes 2-story homes which will have much smaller roof area for the same home square footage. So it's quite reasonable to get from an average cost of $58,200 to $75,000 for my specific home. [0] https://www.forbes.com/sites/sleasca/2017/05/16/tesla-solar-roof-cost/ https://www.forbes.com/sites/sleasca/2017/05/16/tesla-solar-...