1. Subscribersonhouse
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    07 Apr '17 13:51
    https://phys.org/news/2017-04-crystalline-material-silicon-efficiency-solar.html#nRlv

    Big news if it works out.
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    07 Apr '17 18:44
    I cannot wait until 99% energy efficient cheap solar cells are made and out of only cheap materials with only common readily available chemical elements such as carbon, silicon etc.
    That will change everything.
  3. Cape Town
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    08 Apr '17 07:55
    Originally posted by humy
    I cannot wait until 99% energy efficient cheap solar cells are made and out of only cheap materials with only common readily available chemical elements such as carbon, silicon etc.
    That will change everything.
    We will will be producing all our power from renewables long before then, so it won't change much at all.
    What we need now is about a 50% drop in the price of household solar. But keep in mind that the price of the panels is only about a third or less of the cost. The inverter and battery are just as important and don't forget installation costs. That is why utility scale solar is quite a bit cheaper than household solar. But even with prices where they are, the uptake of household solar will continue, and hopefully we can get builders to include it as part of the new buildings. The fact is that solar is cheaper than what is available from the utilities, but most people just don't know that yet, or are too stubborn to change (I bet sonhouse hasn't called solar city yet, even though they could drop his monthly electricity bill).
  4. Standard memberDeepThought
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    08 Apr '17 17:12
    Originally posted by humy
    I cannot wait until 99% energy efficient cheap solar cells are made and out of only cheap materials with only common readily available chemical elements such as carbon, silicon etc.
    That will change everything.
    From what I've read 68% efficiency is a hard limit. The sunlight reaching solar cells is a blackbody spectrum which has some consequences. First any radiation with a frequency less than that corresponding to the band gap energy won't excite electron hole pairs. Photons with an energy greater than the band gap produce super energetic electrons whose energy can't be harnessed, the excess energy is lost as heat. So one can get 1.1eV per photon from silicon. What the material advanced by the group sonhouse's OP referenced has done is find a material that can harness more of the energy from the super energetic charge carriers. This still leaves photons whose wavelength is less than the bandgap, as well as losses from electron hole recombination.

    It's explained reasonably well on the Wikipedia pages on the Shockley-Queisser limit.
  5. Cape Town
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    08 Apr '17 18:29
    The reality is that except for particular situations where space is at a premium, efficiency is not important. What is important is price per Watt. The goal of high efficiency has mostly had to do with the fact that higher efficiency can mean lower cost per Watt. If the price is low enough, doubling the area covered really doesn't matter in most situations. Where one would love to have highly compact solar panels (on a cell phone or car for example) the reality is that even 100% efficiency isn't good enough. Traditionally, high efficiency cells have been valued for use in space, but that is more about mass than area. Lighter materials might be easier to find than higher efficiency.
  6. Subscribersonhouse
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    08 Apr '17 20:041 edit
    Originally posted by twhitehead
    The reality is that except for particular situations where space is at a premium, efficiency is not important. What is important is price per Watt. The goal of high efficiency has mostly had to do with the fact that higher efficiency can mean lower cost per Watt. If the price is low enough, doubling the area covered really doesn't matter in most situation ...[text shortened]... is more about mass than area. Lighter materials might be easier to find than higher efficiency.
    If you double the efficiency, for homes it means half the physical size for the same power. That alone has to lower the cost per watt since there is less installation time and cost.
    One question yet to be answered, even if they make a 60% cell, is lifetime, resistance to moisture which is a huge problem with Perovskites. Time will tell.
    Part of the renewable equation is home installations with excess power available to put back into the grid. If you had 60% cells and used the same area collected and double the power generated, that could go straight to the grid and still power a house.
  7. Cape Town
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    09 Apr '17 05:132 edits
    Originally posted by sonhouse
    If you double the efficiency, for homes it means half the physical size for the same power. That alone has to lower the cost per watt since there is less installation time and cost.
    It only lowers the cost if doubling the efficiency is achieved with similar costing materials.
    Halving the manufacturing costs can be just as effective - and for the higher efficiencies will be much easier to achieve. More importantly, there is a hard limit on efficiency. There isn't one on manufacturing costs.

    Part of the renewable equation is home installations with excess power available to put back into the grid. If you had 60% cells and used the same area collected and double the power generated, that could go straight to the grid and still power a house.
    That is just as true for cheaper cells with a greater area.
    You can have five times the area. You can't have five times the efficiency.

    Most houses, however, can produce enough solar without covering their whole roof, using current efficiencies. The key problem is the up front capital cost. In the US that has been solved by Solar City and others by providing financing, so there is no capital cost and you see an immediate drop in your electricity bill - its a no brainer. That leaves simple resistance to change.
  8. Subscribersonhouse
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    09 Apr '17 12:58
    Originally posted by twhitehead
    It only lowers the cost if doubling the efficiency is achieved with similar costing materials.
    Halving the manufacturing costs can be just as effective - and for the higher efficiencies will be much easier to achieve. More importantly, there is a hard limit on efficiency. There isn't one on manufacturing costs.

    [b]Part of the renewable equation is hom ...[text shortened]... diate drop in your electricity bill - its a no brainer. That leaves simple resistance to change.
    True but some of us can't get solar no matter how much we want it. Financial situation for us right now is dire. May lose home, much less getting solar. A lot of people in the US are in that boat right now. I would have to get a grant of some kind to contemplate solar.

    But doubling the efficiency will put more power into the grid whether it is roof top or solar farms. Install costs are coming down along with the rest. Humy says the limit is 68% so this new generation is withing that limit.
  9. Cape Town
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    09 Apr '17 14:27
    Originally posted by sonhouse
    True but some of us can't get solar no matter how much we want it. Financial situation for us right now is dire. May lose home, much less getting solar. A lot of people in the US are in that boat right now. I would have to get a grant of some kind to contemplate solar.
    Have you tried contacting solar city? If I am not mistaken, they, or other companies like them, can install solar for you, at no cost whatsoever, and your monthly electricity bill will go down. If that is the case it will help your financial situation not harm it.


    But doubling the efficiency will put more power into the grid whether it is roof top or solar farms.
    So will doubling the area. My point is that doubling the area is easier to achieve. Quadrupling the area is possible, quadrupling the efficiency is not.
  10. Subscribersonhouse
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    10 Apr '17 10:12
    Originally posted by twhitehead
    Have you tried contacting solar city? If I am not mistaken, they, or other companies like them, can install solar for you, at no cost whatsoever, and your monthly electricity bill will go down. If that is the case it will help your financial situation not harm it.


    [b]But doubling the efficiency will put more power into the grid whether it is roof top ...[text shortened]... area is easier to achieve. Quadrupling the area is possible, quadrupling the efficiency is not.
    On roofs you can't arbitrarily double the collecting area. Most solar installs I see cover 90% of the roof now, at least on the sun side. I only see a few installs with say 20% coverage. I imagine those would be done by the homeowners who could not afford full roof coverage.
  11. Cape Town
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    10 Apr '17 11:15
    Originally posted by sonhouse
    On roofs you can't arbitrarily double the collecting area. Most solar installs I see cover 90% of the roof now, at least on the sun side. I only see a few installs with say 20% coverage. I imagine those would be done by the homeowners who could not afford full roof coverage.
    Maybe so. I don't see many solar installs here in SA. The fact is that the vast majority of roofs are empty.
    So, given that most installs you see are at 90%, why would they want to double that? Surely they have 90% because that is what they thought they would need. Or are you suggesting that individual home owners should be the primary source of power for industry?
  12. Standard memberwolfgang59
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    10 Apr '17 11:33
    Originally posted by sonhouse
    On roofs you can't arbitrarily double the collecting area. Most solar installs I see cover 90% of the roof now, at least on the sun side. I only see a few installs with say 20% coverage. I imagine those would be done by the homeowners who could not afford full roof coverage.
    Houses of the future will have bigger roofs and need less heating so the
    heat produced will contribute to global warming. A solution is to use solar
    energy to power refrigeration units around the world.

    This is particularly needed at the poles (and efficient as they have "days" of 6 months)
  13. Subscribersonhouse
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    10 Apr '17 15:231 edit
    Originally posted by twhitehead
    Maybe so. I don't see many solar installs here in SA. The fact is that the vast majority of roofs are empty.
    So, given that most installs you see are at 90%, why would they want to double that? Surely they have 90% because that is what they thought they would need. Or are you suggesting that individual home owners should be the primary source of power for industry?
    That would be one goal, rooftop units powering civilization. Of course that is a pipe dream.
    I was talking about 90% of the roof area filled with cells. If you go from 20% cells to 60% cells you triple the power output and the excess can go directly back to the grid.

    Power companies don't really like that for several reasons, one, they have to pay for the electricity generated so they screw the homeowner and only pay 1/3 or so of what they would pay a fill in power company for the same energy and they also bitch about safety issues where if a power line goes out and a dude has to come out to fix it there would be power on the line even though the input power side is disconnected so there has to be extra disconnects in each block to ensure a linesman can work on it. Whoppie deal so built the extra switches. And pay the people what they pay another company for fill in power.

    If we say in the US for instance, there are about 300 million people and about 100 million homes and there might be about 40 meter square area available for cells and at 100% that could be around 40 kilowatts generated, so maximum at 20%, 8 kw and of course that would be divided by at least 3 to call it power 24/7 so about 2.5 kw. Now a house typically uses about 2 kw or 48 kwh so that leaves 500 watts or about 12 Kwh to the grid.

    Now multiply that to 60%, triple everything, and you have 7.5 Kh for about 180 Kwh and 5.5 kw to the grid, or 132 Kwh per day to the grid. That is over 10 times the actual Kwh output to the grid and still giving the house its 48 Kwh it needs.

    Seems like a win win to me. Of course those numbers are just max and it would be less in practice, say half over the space of a year but still that gives over 60 Kwh to the grid average. Still 5 times the result to the grid from 20% cells for the same roof area.
  14. Cape Town
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    11 Apr '17 06:39
    Originally posted by sonhouse
    Power companies don't really like that for several reasons, one, they have to pay for the electricity generated so they screw the homeowner and only pay 1/3 or so of what they would pay a fill in power company for the same energy and they also bitch about safety issues where if a power line goes out and a dude has to come out to fix it there would be power ...[text shortened]... so built the extra switches. And pay the people what they pay another company for fill in power.
    There are two main reasons why power back to the grid is unpopular. There is the question of who pays for the grid and there is the question of profits.
    Currently, the grid is payed for out of the power companies income and they and the local governments share the profits. It is perfectly reasonable for them to pay the home owner less for power onto the grid than they charge for power off the grid. But if enough people have rooftop solar, the loss of profit is unavoidable as the 'profit' is essentially going to the homeowners in form of a reduced power bill.
    In the long term we need to ask whether or not we should keep the grid at all. It has many advantages, but they might not be worth the cost.
  15. Subscribersonhouse
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    11 Apr '17 11:40
    Originally posted by twhitehead
    There are two main reasons why power back to the grid is unpopular. There is the question of who pays for the grid and there is the question of profits.
    Currently, the grid is payed for out of the power companies income and they and the local governments share the profits. It is perfectly reasonable for them to pay the home owner less for power onto the ...[text shortened]... ot we should keep the grid at all. It has many advantages, but they might not be worth the cost.
    Seems we would still need the grid because of industrial use of electricity goes way beyond that of homes, megawatts and more. I used to work at Firestone tire and rubber in LA and one of my machines was the 'Banbury 27', a system that ground rubber and other stuff in a huge mixer, with a 1500 horsepower electric motor that ran at 200 RPM, big as a house. It was geared down to 16 RPM to run the actual mixer that took in 500 pounds of rubber and oils an stains in a given recipe and ground them all up and such then feeding the output to a continuous production line. That motor had a megawatt power meter on it that pegged when it started up and then settled in to a couple of megawatts. You need grid for that kind of usage. If you have a production plant using say 50 megawatts you would be hard pressed to get that with solar. say 1000 watts hits the ground per square meter so 1 megawatt needs 1000 square meters times whatever efficiency percentage so 20, 5000 square meters times 3 for 24/7 and now it's 15,000 square meters just for one megawatt and then times 50 to get that 50 megawatt number and you are talking 750,000 square meters of collection space at 20%. 60% = 250,000 square meters and even that is a half kilometer by half kilometer space.
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