7 ms·

Payback of 6 years with the new cost, even for your low electric bill.

toomuchtodo 10y ago
Excellent example of why solar panels (in the right locations) and LEDs are a better investment than the S&P500 right now. You spend dollars now to eliminate the need for future dollars.
- antisthenes 10y ago
  While that is true, keep in mind that future dollars are less expensive than present dollars. But it stands to reason that the prices of energy will rise faster than the rates of inflation, so it would still be a good investment.
  - Someone 10y ago
    If everybody buys solar, electricity prices will only rise faster than inflation in periods without much sun. It might even be profitable to play a 'buy when it is free or cheaper, use when it costs money' strategy. You can get there by buying large batteries, charging them from your neighbor's solar panels when there is lots and lots of sun (they may even sell at prices below zero), and discharging them, selling to you neighbors, when there is little sun and wind.
    - toomuchtodo 10y ago
      I'm already investigating buying 50+ MW at a time of Tesla Powerpacks in certain markets exactly for this purpose, as an independent generator. Buy power when people are paying you to take it, releasing it back to the grid at the most expensive times.
mrec 10y ago
And presumably a lower bill implies lower energy usage, so he'd need fewer panels to cover it.
dragontamer 10y ago
Unlikely. Solar Panels don't replace all of your electricity costs. Naturally, you'll still run your refrigerator at night, right? And during the day, when you have peak-solar energy, you'll be at work and won't be taking advantage of it. You'll recoup some of the costs through net-metering, but you usually buy back at wholesale prices and not at retail prices. Finally, I'd expect utility companies to change their pricing scheme in the near future to account for solar. They service your electrical wires for example, and you'll likely have to pay a certain amount of money for that. So while you're not buying "power" (or at least, as much power) as before, you'll still have the service cost of being hooked up to the grid.
- kragen 10y ago
  Unless it's dorm-fridge-sized, you can definitely run your refrigerator only during the day, generating ice to cool it during the night. Building HVAC systems often work this way, running the chiller to generate ice during the night (when electricity prices are low or even negative) and running the resulting chilled water through heat-exchanger coils during the day. And superinsulated fridges like Sunfrost models can stay cool during the night even without such extra thermal reservoirs. A thing I haven't seen, but which ought to be practical, is a solar thermal fridge — for example, using the ammonia-absorption cycle that propane-powered fridges use, but heated with sunlight instead of flames. PV panels are typically 16% efficient, but it's easy for solar thermal collectors to reach 50% efficient, and they're also about five times cheaper per unit area (still). So you'd think it would make sense to power the fridge directly from sunlight.
  - coredog64 10y ago
    As an EMH guy, I'd like to think that if an Einstein–Szilard cooler was more economical than grid power for A/C and/or food refrigeration that there'd already be systems for sale.
    - kragen 10y ago
      There are absorption refrigerators for sale for food refrigeration — I had one in my Volkswagen — but I don't think they use the Einstein-Szilard design, but a simpler one. Here's one: http://www.amazon.com/Norcold-Inc-Refrigerators-N841-Refrigerator/dp/B002OW6WYU/ref=sr_1_5?ie=UTF8&qid=1462304535&sr=8-5 http://www.amazon.com/Norcold-Inc-Refrigerators-N841-Refrige...

Excellent example of why solar panels (in the right locations) and LEDs are a better investment than the S&P500 right now. You spend dollars now to eliminate the need for future dollars.

antisthenes 10y ago
While that is true, keep in mind that future dollars are less expensive than present dollars. But it stands to reason that the prices of energy will rise faster than the rates of inflation, so it would still be a good investment.
- Someone 10y ago
  If everybody buys solar, electricity prices will only rise faster than inflation in periods without much sun. It might even be profitable to play a 'buy when it is free or cheaper, use when it costs money' strategy. You can get there by buying large batteries, charging them from your neighbor's solar panels when there is lots and lots of sun (they may even sell at prices below zero), and discharging them, selling to you neighbors, when there is little sun and wind.
  - toomuchtodo 10y ago
    I'm already investigating buying 50+ MW at a time of Tesla Powerpacks in certain markets exactly for this purpose, as an independent generator. Buy power when people are paying you to take it, releasing it back to the grid at the most expensive times.

mrec 10y ago

And presumably a lower bill implies lower energy usage, so he'd need fewer panels to cover it.

dragontamer 10y ago

Unlikely. Solar Panels don't replace all of your electricity costs. Naturally, you'll still run your refrigerator at night, right? And during the day, when you have peak-solar energy, you'll be at work and won't be taking advantage of it. You'll recoup some of the costs through net-metering, but you usually buy back at wholesale prices and not at retail prices. Finally, I'd expect utility companies to change their pricing scheme in the near future to account for solar. They service your electrical wires for example, and you'll likely have to pay a certain amount of money for that. So while you're not buying "power" (or at least, as much power) as before, you'll still have the service cost of being hooked up to the grid.

kragen 10y ago
Unless it's dorm-fridge-sized, you can definitely run your refrigerator only during the day, generating ice to cool it during the night. Building HVAC systems often work this way, running the chiller to generate ice during the night (when electricity prices are low or even negative) and running the resulting chilled water through heat-exchanger coils during the day. And superinsulated fridges like Sunfrost models can stay cool during the night even without such extra thermal reservoirs. A thing I haven't seen, but which ought to be practical, is a solar thermal fridge — for example, using the ammonia-absorption cycle that propane-powered fridges use, but heated with sunlight instead of flames. PV panels are typically 16% efficient, but it's easy for solar thermal collectors to reach 50% efficient, and they're also about five times cheaper per unit area (still). So you'd think it would make sense to power the fridge directly from sunlight.
- coredog64 10y ago
  As an EMH guy, I'd like to think that if an Einstein–Szilard cooler was more economical than grid power for A/C and/or food refrigeration that there'd already be systems for sale.
  - kragen 10y ago
    There are absorption refrigerators for sale for food refrigeration — I had one in my Volkswagen — but I don't think they use the Einstein-Szilard design, but a simpler one. Here's one: http://www.amazon.com/Norcold-Inc-Refrigerators-N841-Refrigerator/dp/B002OW6WYU/ref=sr_1_5?ie=UTF8&qid=1462304535&sr=8-5 http://www.amazon.com/Norcold-Inc-Refrigerators-N841-Refrige...