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High efficience rooftop PV, hybrid PV+Thermal solar, concentrating solar PV

Discussion in 'Energy, Environment, and Policy' started by macpacheco, Oct 14, 2015.

  1. macpacheco

    macpacheco Member

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    SolarCity's announcement of 22% efficient PV got me thinking.

    What matters is having top efficiency at a cost efficient price point. 22% efficient solar panels can cost more per Watt than 15% ones, but it can't cost 50% more/Wp.

    Anyone cares to predict when 20%+ efficient solar panels will make the other panels obsolete (due to lower installation costs and better utilization of roof space) ?

    Ultimately getting rid of fossil fuels will require those that both have the money and have the inclination to invest to convert their houses into a mini solar grid generator. I mean at 200% over generation whole year, ideally 500% or more. Having 200kWp of solar panels (or bigger). Unless you have a mansion, you're likely to be roof space constrained. Oh, and at one PowerPack for each 100kWp worth of panels (ideally 3 PowerPacks for each 100kWp so one can sell electricity at peak demand hours).

    Ok, I'm writing from the seat of my pants. I don't live in the USA. I live in Brazil where most people live in buildings 4-20 floors high. The solution here would by ultra high efficient hybrid solar PV+Thermal or PV concentrating generation in order to just break even for buildings with 10+ floors.
    Any thoughts would be interesting.

    There is an Israeli Solar Hybrid system advertised to achieve 72% efficiency, but at what price point ? Zenith Solar Israel.

    Thanks for any thoughts.
     
  2. Saghost

    Saghost Active Member

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    Random thoughts, not really strung together into conclusions:

    Legal issues prevent people from becoming power stations in the US - once you exceed your consumption by a significant percentage, you start having to follow the same laws as public utilities I believe.

    For most applications in the US right now space limits aren't critical so the lowest cost per watt wins, period. That will slowly continue to trend up in efficiency over time, but it's doubtful it'll ever approach the high end of the market (now, exceeding the high end of the current market in a few decades is not only possible but likely...)

    That 72% sounds really impressive - until you realize it's the combined electric and thermal and mostly (71%) thermal at 100C or less - to cold for steam cogeneration or industrial processes. The solar electric generation efficiency would appear to be in the mid 20s somewhere. (Dedicated solar thermal devices routinely run in the 90% efficiency range - it's just hard to make good use of the energy unless you get up into the 300C range.)

    Do the people living in apartment building drive cars? If so, carport roof solar is a logical choice - like the roof Tesla has on a few Superchargers now and hopes to put on most of them eventually.
    Walter
     
  3. macpacheco

    macpacheco Member

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    Brazil is likely to be the last country to get a lot of EVs. Brazil should be a net exporter of oil, our largest oil company is state owned, jobs/politics/corruption. So, right now we have a few Leafs being used as cabs in some capital cities, just because local municipalities are giving them substantial tax breaks. In theory a left wing govt shold be pro environment, but in fact they do it for show, only when they can profit with corruption on large $$$ projects.

    For instance from a Toyota corolla to a prius to a leaf... R$ 80k ... R$ 130k... R$ 200k. For R$ 130k you can buy a tiny apt. For R$ 200k you can buy a small apt. Minimum wage is less than R$ 1000/month. Middle class is considered above R$ 5000/month.
    Financing is crazy expensive, interest alone... We pay in a month interest americans pay in a year on a loan with full guarantees.
    Brazil has everything needed to be a developed country, except the lets just do it attitude of Americans and a minimum sense of morality.
     
  4. Robert.Boston

    Robert.Boston Model S VIN P01536

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    That's true only if (a) space is unlimited and (b) installation and balance-of-plant costs are the same. The latter is surely NOT true; high-efficiency panels require fewer racks, fewer inverters, and less time to install. The makers of high-efficiency panels can price to capture some (or all) of these savings. Furthermore, space MAY be at a premium in some applications. wk057 had to take over a big chunk of his lawn to install all the capacity he wanted; with high-efficiency panels, they all might have fit on his roof. Weight can also be a limiting factor: many large flat-roofed buildings (big box stores, warehouses, schools) weren't engineered with enough extra weight-bearing capacity to add lots of panels, so having high-efficiency panels makes the most of the available weight capacity.

    Bottom line: SolarCity will be able to charge a handsome premium for these panels until someone catches up.
     
  5. macpacheco

    macpacheco Member

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    Doesn't Solar City mostly sell energy rather than panels ?
    There already are competitors in the 20+% efficiency range.
    Those panels aren't yet in full production.
    Until then Solar City will prefer to use the early production on projects that are space constrained. Or when people want to buy the solution.
    So far they had to buy everything from third parties, I think.
    The advertised efficiency isn't the full story. Solar PV has temperature losses, so it might turnout a 22% efficient panel might perform better than a 22.5% depending on the whole picture.
    The full specs of the panels haven't been released yet. Once that's available a real comparison can be made.
    Solar City's announcement was much like PowerPack announcement. Bragging rights and mind share. It will take 6 months to a year before those hit the shelfs in big enough numbers.
    The other reason I like the concept of blanketing the sunniest side of your roof with high efficiency panels is you're actually cooling down your house quite a bit, less AC demands. Every kWh that becomes electrons or is reflected is less work your AC needs to perform.
     
  6. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Active Member

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    Indeed. The combination of retrofitting and limited roof space places a premium on efficiency. SolarCity's aim is to lower system cost per kWh, because they price per kWh.
     
  7. omgwtfbyobbq

    omgwtfbyobbq Member

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    Does anyone have any $/W figures on the Solar City or SunPower high efficiency panels?
     

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