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View Diary: Solar Energy Cheaper than Coal? (351 comments)

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  •  efficiency not the be-all and end-all. (9+ / 0-)

    it matters if the panels themselves are expensive.
    but if you can afford to roof your house with the aluminum sheets, the relative efficiency is less significant, as long as they are efficient enough for a rooftop-full to power your home.

    there is another company (google ovonics) that has a technique for putting relatively inefficient cells on sheets of steel.

    in the end, the bottom line that matters is the $/watt.

    I am further of the opinion that the President must be impeached and removed from office!

    by UntimelyRippd on Tue Dec 18, 2007 at 06:17:44 PM PST

    [ Parent ]

    •  Agreed (8+ / 0-)

      It's the price per watt installed that is the question - it doesn't matter how efficient they are if the end product is cheaper.

      Mind you, oil isn't really efficient itself.  Here's the efficiency of oil:

      Algae receive sunlight.  They convert about 6% of this sunlight into energy through photosynthesis.  Algae die in a swampy area where they don't fully decay.  Swampy area is crushed under the weight of geological formations, which take enormous amounts of energy to move.  Guy sticks a pipe in the ground, oil shoots up.  Perhaps one millionth of one percent of the energy necessary to create the oil actually is released when you fill up at the local Lukoil.  

      Oil is only cheap because we didn't have to pay for the land on which the algae grew hundreds of millions of years ago, and because we are free riders on the geological process.

    •  No, but it is critically important (1+ / 0-)
      Recommended by:
      wondering if

      Efficiency (in the sense of power per unit volume) is why electrics and other such technologies aren't near supplanting petroleum for vehicle fuel: gas has such a high energy density that at the moment it easily outcompetes other portable fuel sources.

      Efficiency in terms of of power generated per area is a similar issue.  Not everyone lives in sunny southern California.

      Of course I'm all for people using as much solar as possible, but there are trade offs and limits on what's possible with it.

    •  Efficiency wasn't really the point (0+ / 0-)

      My point was really that solar hot water right now has the best return on solar investment.  Both in terms of energy return per square-meter and also in terms of energy return per dollar invested.

      So if people want to make an immediate impact for the least investment, hot water is the right first step.

      There are two payback periods for solar.  The carbon neutral point and the cost neutral point.  Carbon neutral is how long it takes to regain the energy cost of manufacturing the panels and associated equipment.  And cost neutral is how long it takes before you get more saving in utility bills than it cost to install.

      Solar PV is about 2-4yrs for carbon neutral.  And depending on area, it's 15yrs (california) - over 30yrs for cost neutral.  So that's a problem.

      Solar hot water is normally one season for carbon neutral.  And 3-5 years for cost neutral.  So from a home owner or tax policy perspective, we can make a big gain at low cost by starting with solar hot water.

      Even bigger gains possible by using solar radiant heat instead of natural gas or heating oil.  But that requires new construction or significant remodeling.

      Hopefully technology like Nanosolar will continue to be developed.  I'd like to see solar PV be a good financial investment for every home owner.  But too much focus on PV diminishes the focus on getting energy from the already mature and excellent ROI offerings available for hot water.

      For links, google "evacuated tube solar" or "solar hot water"

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