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Method for $1/Watt Solar Panels Will Soon See Commercial Use 502

An anonymous reader writes "A method developed at Colorado State University for crafting solar panels has been developed to the point where they are nearly ready for mass production. Professor W.S. Sampath's technique has resulted in a low-cost, high-efficiency process for creating the panels, which will soon be fabricated by a commercial interest. 'Produced at less than $1 per watt, the panels will dramatically reduce the cost of generating solar electricity and could power homes and businesses around the globe with clean energy for roughly the same cost as traditionally generated electricity. Sampath has developed a continuous, automated manufacturing process for solar panels using glass coating with a cadmium telluride thin film instead of the standard high-cost crystalline silicon. Because the process produces high efficiency devices (ranging from 11% to 13%) at a very high rate and yield, it can be done much more cheaply than with existing technologies.'"
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Method for $1/Watt Solar Panels Will Soon See Commercial Use

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  • by acdc_rules ( 519822 ) on Sunday September 23, 2007 @03:28PM (#20721227)
    ya, but for how long do they last
    • by arivanov ( 12034 ) on Sunday September 23, 2007 @03:31PM (#20721251) Homepage
      I agree. A few obvious questions: what is the actual performance deterioration curve, what is the efficiency after 5-10 years and what are the disposal requirements (it has the dirty "C" word in so do not expect them to be accepted at the tip).
      • by Lumpy ( 12016 ) on Sunday September 23, 2007 @04:14PM (#20721623) Homepage
        Exactly! $1 a watt panels are darn expensive if they only last 5 years.

        I run on 20 year old Solar panels here. I buy only used and discarded from solar plants out west and they look brown from the years of solar exposure but cost me far FAR less than buying new so I can afford more watts for the money. Decent used one approach $2.00 a watt but that is at higher voltages. and my panels will last another 30 years easily with care.
        • by Anonymous Coward on Sunday September 23, 2007 @06:05PM (#20722367)
          Well, if exposure to the sun is going to cause them to deteriorate and turn brown, you should probably try to install them in a shady location to prolong their life.

          Depending on the investment in the solar panels, I might even consider setting up some sort of permanent awning to protect them from the sun at all times - protecting my investment as it were.
          • by Anonymous Coward on Sunday September 23, 2007 @06:12PM (#20722401)
            But an awning can only offer so much protection ... really the only surefire way to protect your solar panels from sunlight-induced degradation is to install them in some kind of underground environment where they are completely isolated from the environments.
            • by MrNaz ( 730548 ) on Sunday September 23, 2007 @08:10PM (#20723163) Homepage
              You guys are amateurs. I have installed my solar panels in an underground cave with a sealed access point along with my wind turbines. My solar panels never deteriorate due to solar degradation and my turbines never suffer the terrible wear and tear that is caused by constant motion. I figure that they should last 10x as long as an irresponsibly deployed solar/turbine array, which means I'll get 10x the return on my investment!
              • by irtza ( 893217 ) on Sunday September 23, 2007 @10:33PM (#20723967) Homepage
                wow, I was reading this thread and was utterly shocked at how people could get things so backwards. solar panels were meant to be used - degradation is inevitable. There is no need to protect them from the environment; you need to expose them to more environment. With only 11% efficiency you need as much light energy as possible to capture. That is why I poor kerosene on mine and light them ablaze. With all that direct light from the fire, I get unbelievable amounts of power before the unit dies.
                • Re: (Score:3, Funny)

                  by Afecks ( 899057 )
                  ya but for how long do they last
                  • Re: (Score:3, Funny)

                    I agree. A few obvious questions: what is the actual performance deterioration curve, what is the efficiency after 5-10 kerosene burns and what are the disposal requirements (it has the dirty "C" word in so do not expect them to be accepted at the tip).
                    • Re: (Score:3, Insightful)

                      by russellh ( 547685 )

                      I think the most important question is what would mass adoption of solar power due to our power grid. Non-solar generated electricity would go through the roof, for starters - causing the adoption rate to increase - again causing rates on non-solar energy to increase - until at some point the power companies wouldn't be able to afford to operate their grids anymore.

                      It's an interesting thought, although I have to admit it reminds me of that guy in college who didn't want to work out because he didn't want

        • Re: (Score:3, Informative)

          by eonlabs ( 921625 )
          Why are you so concerned about the voltage in this case, Wattage describes the actual energy you're drawing out of the panel. A transformer (no comments on the series) provides 99+% efficiency to ramp voltage up at the cost of current, and a power inverter is needed in some form regardless if you intend to use any standard appliances on your clean energy source.

          Just for clarity for those who don't know:
          Watts are a rate of flow for Joules.
          Joules are a unit of energy (kg m^2 / (s^2)) which describe the dista
        • Re: (Score:3, Interesting)

          by RingDev ( 879105 )
          I pay about $0.05/kilowatt here. Assuming I spent $1000 for 1Kw worth of panels, they would have to generate 20Mw worth of juice to pay for themselves. I average 700Kw/month, or about 8.4Mw/year. So if 1Kw worth of panels could entirely offset my electrical bill (sell back extra in the summer, buy back more in the winter), they would only have to last 3 years to make a profit. Who cares if they only last 5-10 years, at $1/watt they'll be a net gain for the consumer before they burn out. Even if they can onl
      • Back of the envelope (Score:5, Interesting)

        by goombah99 ( 560566 ) on Sunday September 23, 2007 @04:32PM (#20721743)
        Lets see. Assume the competing cost is at present 10 to 25 cents per KW-hour. We'll use the upper end because future power prices will rise whereas the Solar panel is a fixed cost.

        So let's see the solar panels are 100000 cents per KiloWatt. if the last 4000 then that's breakeven. We'll assume that the power is available 10 hours per day. That's not realistic for individual use but perhaps with batteries, and selling back to the grid this could be done. So 4000 hours is 400 days. Or about 1 year. Not too bad.

        Now that ignores the efficiency of either pushing back to the grid or battery storage. Let's assume 50% loss. Then this is 2 years to payback on the cells. But now we also have to payback on the batteries. Let's assume the batteries needed const aout the same as the solar cells. That would double this payback to 4 years.

        Finally this is assuming capital is free. Assume one borrows at 8 % interest. Then this another 5 months to payback.

        So the whole operation needs to run undegraded for 4 to 4.5 years I estimate for break even.

        That figure could be cut in half if one could sell back to the grid rather than batteries. ( Fine--as long as there is a grid and every one does not do that!. )

        If the cells were down to 50% effiency after 4 years then this extends out to ~7 years to payback. If one cannot get that watt for the full ten hours then this gets even longer.

        It sounds to me, roughly speaking that at 1 dollar per what things are in the ballpark for breakeven.

        • Re: (Score:3, Interesting)

          by Biogenesis ( 670772 )
          10 to 25c/kwh ignores the connection fee though. My parents are considering solar for a small weekend house on a 40 acre property they own (on the North coast of NSW, Australia). The local provider (Country Energy) recently increased the cost of connection from ~40c to ~60c per day, and since we're there about 4 days a month, and just run an electric fence continuously, this equates to almost all of the bill, making solar power without a grid connection far more attractive, and shortening the payback time s
        • Re: (Score:3, Informative)

          by bcrowell ( 177657 )
          Your back-of-the-envelope calculation is fine, but it's just that, a back-of-the-envelope calculation. The present situation is that PV panels are already at the break-even point for some people -- we're the ones who have done more than a back-of-the-envelope calculation, and found out that it makes sense for us. It depends on your latitude, how much sunny weather you get every year, which way your roof faces, how much electricity you use, how much roof space you have, and the alternatives that you have ava
          • Re: (Score:3, Informative)

            by Firethorn ( 177587 )
            If it wasn't already at the break-even point for some people, the industry wouldn't exist.

            Doesn't have to be break-even. Most people don't buy the most efficient vehicle that will meet their needs, they go larger. Decisions are not always purely economic.

            Of course, how much value an individual puts into being green or grid-independent varies, so it's tough to calculate. Solar panels, perhaps unfortunately, aren't as sexy as hot cars.

            Still, solar has made sense in a number of remote locations for years no
      • by mdsolar ( 1045926 ) on Sunday September 23, 2007 @04:54PM (#20721883) Homepage Journal
        FirstSolar uses CdTe [] and the durability of the panels remains an issue, but one they are addressing. Their aim is to demonstrate 20 year performance above 80% of the initial efficiency. The trick is to do this in less time than 20 years and they are getting help from NREL to pull this off. Their cost of production is $1.19/Watt and headed down.
        Rent solar power for your home and save: []
    • by An Onerous Coward ( 222037 ) on Sunday September 23, 2007 @04:51PM (#20721857) Homepage
      According to this article [], they expect the things to last about twenty years, but they're still running stress tests. Same program, but a little over a year ago.

  • by cyfer2000 ( 548592 ) on Sunday September 23, 2007 @03:29PM (#20721239) Journal
    I have always been worrying the environmental impact of the cadmium. Could some one show me that the cadmium used in the photovoltaic has little or no environmental impact please?
    • by Dunbal ( 464142 ) on Sunday September 23, 2007 @03:42PM (#20721343)
      Could some one show me that the cadmium used in the photovoltaic has little or no environmental impact please?

            You don't need to worry about the environmental impact of cadmium, but rather the environmental impact of cadmium versus the environmental impact of current energy production from fossil fuels, etc.
    • by Anonymous Coward
      Let's be like China and make electricity the man's way - with coal! And let's go back to burning leaded gasoline so we don't have to fuck with this unleaded crap that limits engine compression. Also, catalytic converters suck. I always take mine off after inspection or go to shops that don't care. Also, we need to get rid of welfare and we need George W. Bush for another eight years! And fuck solar cells. Solar cells can't even power calculators properly.

      Anonymous Coward Sig 2.0:
      Write in George W. Bush in
    • Management of the environment is constant compromise since nothing is perfect. However. Since burning coal is the major SOURCE of Cd in the environment ...a quick web search reveals a sense of the tonnage: [] a balanced view considers the following. Which is cleaner? a) a highly controlled manufacturing process b) under-regulated coal bonfires belching Cd in the air and disgorging Cd in the ash. Bonus question: for extra credit what other nasty stuff
    • How about the environmental impact of all the two stroke chainsaws cutting down C02 absorbing trees in order to provide direct sunlight to the roofs where the solar panels will be installed? That is being said kinda "tongue in cheek" but it might be a consideration. An even greater consideration to me personally would be the effect of the loss of shade on my house during the hot summer months. I don't even want to think what my AC would cost without the wonderful shade of 30+ year old trees that surround
    • A 2003 study on French dietary intake showed an average intake of 3.6 micrograms cadmium per day. Multiply that by the us population of around 300 million, and the US population should be able to safely consume at least 9 grams of cadmium per day. Multiply that by 365 days a year, and we (as a nation) should be able to ingest at least 3.2 kilograms over the course of the year.

      Therefore, the solution to the cadium waste is obvious. Put it in the water. After all, dilution is the solution to pollution.
  • Impresive (Score:2, Insightful)

    by Jarik C-Bol ( 894741 )
    if it turns out to not be vaporware, it may very well actualy make a dent in our use of coal and other fuels for generating electricity.
    • Definitely. $1/W is impressive. Assuming electricity costs 10/kWh, you'd need it to run for 1000 hours to break even, which is under a year even if it only works for an hour or so either side of noon. This is a lot better than any I've seen elsewhere.
      • One thousand hours at one watt is one kilowatt hour, or ten cents; so you really need 10,000 hours to get back your one dollar per watt for the panels. In a good location this would take about five years, still a good return on the investment.
        • I realised that as soon as I posted. I was hoping it would get moderated -1 wrong before anyone saw it.
        • Re: (Score:3, Interesting)

          by Firethorn ( 177587 )
          Starts looking a little worse once you figure install costs - another $1-1.50/watt, generally speaking []

          Add another $.50-1/watt for the inverter [] and miscellaneous, and you're up to $3/watt of capacity.

          10k hours, figuring 8 hours a day, 365 days a year would be 3.4 years for raw payback on the panels. If you're not that optimum, it'd stretch to 4-5 easily.

          Figure in the cost of the inverter and installation, and it jumps to 12-15 years easily, before any cost of capital expectations.

          They not only have to make
      • Re:Impresive (Score:4, Interesting)

        by kesuki ( 321456 ) on Sunday September 23, 2007 @05:01PM (#20721921) Journal
        with conventional solar pannels the cost per watt is around $3-$5. so the $1 per watt price isnt that impressive, what is impressive is the scale at which they can produce these new panels... they could sell self install kits at wal-mart and still have no problem with inventory..

        conventional panels have always been restricted by the amount of pure silicon that can be produced, and with microprocessors using the same pure silicon its been tough for solar panel makers to have enough supply to meet demand. in fact the major tech companies have multi year contracts on 99% of the pure silicon being produced world wide.

        btw this technology does not cheapen solar power to utility electric rates.. according to a website about solar energy Around 59% of world solar product sales installed the last five years were in applications that are tied to the electricity grid. Solar Energy prices in these applications are 5-20 times more expensive than the cheapest source of conventional electricity generation, although they may only be 3-5 times the electricity tariff that utility customers pay. By contrast, PV can be fully cost competitive on economic grounds in remote (off-grid) industrial and habitational applications. []

        so cutting the solar panel cost to 1/2 of what it was before makes solar a preffered method of off-grid electrical applications, and brings the total consumer cost down to levels (15cents/kwh) that they would actually pay for electricity. still not ideal, if they can bring the cost down further with economies of scale, then this will start a revolution for earth-friendly consumers who will be able to take out a loan to buy a $10k system that cuts their electric bill by 25% (to fully power a house with typical energy usage would run about $40k with these pannels, or $80k with normal solar pannels) which means the pannels would have to last at least 34 years to recoup the cost invested in installing a solar system. (theyd have to last for 68 years with normal solar panels) now if youre using a grid+solar setup you can probablly keep using those solar panels as long as theyll crank out energy, but of course they do degrade over the years, producing less energy... and widespead solar power adoption will cause winter energy spikes, but if they have to have coal fired plants that they only run 3 months a year, because of widespread solar adoption... well itll be an improvement.

        $1 per watt is frankly about 10 times more expensive than we need to get solar energy for solar electric companies to adopt the technology without government subsudies/regulation.

        this is why companies like excell energy are turing to wind turbines to meet the 20% renewable energy production mandate minnesota has put them under by 2020.. wind turbines are ALREADY produced around the COST per kwh of coal fired plants. (theyre sold for more obviously though)

        wind energy is a natural byproduct of solar energy, and with the new tidal stream generators it is possible that the uk and scottland could see more than 10% of their total electrical consumption produced entirely from rapidly moving undersea currents.

        tidal projects obviously have less problems with home owners that wind farms, and since areas with high tidal streams tend to be far from good scuba diving sites there should be little complaint about installing tidal stream generators.. in the handful of places where they are genuinely viable.

        its nice to know that more californians will be able to afford a basic solar install, but this isnt something so revolutionary that were going to stop building coal fired plants because of it.
  • by fymidos ( 512362 ) on Sunday September 23, 2007 @03:34PM (#20721285) Journal
    The article doesn't mention how many watts per square meter this panel will produce. The cost of the panel is important, but so is the cost of the land required and the return of your investment.
    • by Alioth ( 221270 )
      The land required is probably taken up by your roof already, so there's no cost to the land (because it's already occupied by something else).
    • If everyone put them on their roofs, that would probably go a long way.
      • by fymidos ( 512362 )
        Not so much, how many roofs/citizen do you think there are in major population centers? (Most of which are not in very sunny places anyway)
    • Simple conversion (Score:5, Insightful)

      by Khyber ( 864651 ) <> on Sunday September 23, 2007 @03:49PM (#20721393) Homepage Journal
      One square meter of land on a bright sunny day will get appx 1.6kW of light in an hour. Assuming 11-13% efficiency as mentioned in the article, you'd get just a little over 160 watts per square meter per hour.
      • Re:Simple conversion (Score:5, Informative)

        by Zebra_X ( 13249 ) on Sunday September 23, 2007 @03:53PM (#20721429)
        1.6 is very high. A more practical estimate is between 800W and 1.2kW.
      • One interesting thing that occurred to me is that at $1/W it's close to the cost of a battery for my laptop. If they can be folded up, it would be a nice power supply for the summer. Make it into some form of parasol, and let me sit outside in its shade, with my own source of power.
      • by BlueParrot ( 965239 ) on Sunday September 23, 2007 @04:19PM (#20721659)

        One square meter of land on a bright sunny day will get appx 1.6kW of light in an hour

        Eh? Power = Energy / Time
        1.6kW is a measure of power, not energy. You probably meant that 1 square metre receives 1.6kW hours of energy in an hour, which would give 160W hours per hour per square meter, or in power terms, 160W/m^2. That is, about the same power as would be necessary to power 3 strong light bulbs.

        Somehow I think a 1m^2 window would be simpler, and if you use a triple glazed argon filled one ( as the Germans do for the passive-house standard) then you can neglect heat loss (in fact, you can get a net heat-gain ), making them considerably more efficient than chaining a 11% solar panel to an energy saving light bulb with 7%-8% efficiency (giving an overall efficiency of about 0.8% ).

        No, really, in the vast majority of cases your money is better spent on insulating your house.
        • Re: (Score:3, Interesting)

          by jesup ( 8690 ) *
          Trust me, I have ~80 windows (a fair number of them large, 7' x 4', and a lot of 2'x6', all double-pane), and you can not ignore heat loss from windows. South-facing windows with the right makeup and coatings can be net energy-gains - but I guarantee you that north-facing ones don't, and heavily-shaded ones don't, and cloudy days don't help... And they don't help at night (nor would solar, except that you get to "store" the power in the grid via net-metering). Plus you have to size the heating system for
      • Re: (Score:3, Informative)

        by jbengt ( 874751 )
        The number you quote seems to be closer to the extraterrestial solar flux of between 1.3 and 1.4 kW/square meter. []
        According to ASHRAE, a horizontal surface on the earth will get around 256 btuh/sq ft peak at noon on a clear, sunny day. By my calcs, that's about 800 Watts/sq meter.
        For yesterday's data on actual insolation at the surface in the Western US, see this: []
      • by Solandri ( 704621 ) on Sunday September 23, 2007 @09:51PM (#20723713)
        ~1600 W/m^2 is the solar energy flux in space (I've heard 1500, but let's go with your figure). The atmosphere absorbs a good chunk of that, so on the ground you're talking more like 700-900 W/m^2. Then you factor in:
        • Night (50% averaged for the year).
        • Suboptimal angling on the panel relative to the sun throughout the day (guessing pi/4 since I'm too lazy to do the integral).
        • Weather (highly dependent on location but this report [] says 54% in the northern hemisphere, let's use 30% to account for light that manages to get through the clouds).
        • Panel efficiency (12%).
        • Conversion losses. I should be including losses converting solar panel DC into the AC most household appliances use, but let's be optimistic and say these panels spur development of DC appliances.
        • Battery efficiency. Unless you plan to use your lights only during the day, you're going to have to store electricity for night use. Lead acid batteries are about 90% efficient. Wild guess, but say a half of your daily electricity use will be drawn off the batteries, yielding an average 95% battery efficiency. Yeah you could draw electricity off the grid at night, but since we're hypothesizing DC appliances and throwing away conversion losses, I think this is the smaller of the two.
        Phew. So what do we have? 1600 W/m^2 * 0.5 (atmosphere) * 0.5 (night) * pi/4 (angling) * 0.7 (weather) * 0.12 (panel) * 0.95 (battery) = 25 W/m^2. That's probably a more realistic figure to use if you want to calculate how much electricity use the panels will save you over a year. The average U.S. home consumes about 1 kW (averaged over the year), so to completely take each home off the grid would require about 40 m^2 of panels. You'd probably want more than that to get you through the Winter months and long bouts of bad weather, but that's very location-specific. We'll just use 40 m^2 and calculate a minimum.

        Assume the $1 per Watt figure is under ideal conditions (companies love to do that). 800 W/m^2 * .12 = 96 W/m^2. So a square meter of this stuff will run you $96. Multiply by the required 40 m^2 to yield $3840 per home.

        Figure an average electricity cost of $0.13 per kWh (in the higher priced areas where this stuff will be used first). Average home burning 1 kW (yearly time-average) would thus spend 24*365*1 kWh = 8760 kWh for the year. At $0.13 per kWh, that's $1139/yr in electricity costs. Ignoring installation labor, the panels would pay for themselves in 3 years and 4.5 months at earliest. Adjust up depending on your latitude and weather. Adjust down if you aren't as power-hungry as homes in the U.S.

        I think we have a winner.

    • It lists the efficiency. The watts per square meter will depend on the amount of sunlight in your location. 13% is mid-range, people have made up to 60%, but those are state-of-the-art and expensive.
    • by rcw-home ( 122017 ) on Sunday September 23, 2007 @03:58PM (#20721487)

      The article doesn't mention how many watts per square meter this panel will produce.

      It did mention efficiency, so you can calculate it. Find an insolation map [], find your location on it, find the average kWh/day you get, and multiply by the 11-13% figure mentioned in the article.

  • by saterdaies ( 842986 ) on Sunday September 23, 2007 @03:40PM (#20721325)
    Well, 1 kilowatt for an hour costs me 25 cents (thereabouts). To make a kilowatt, I would need to spend $1,000 on these. That means that they would have to operate for 4,000 hours for me to make my money back (well, 4,000 hours of electric usage).

    Basically, it looks like, if they last a couple years, they would pay for themselves (166 days of full utilization, but that's not going to happen in the real world). Not bad. If they're durable (and last 5-10 years), they could really cut down on electric costs.

    Oh, plus the whole saving the planet from destruction thing. I guess that might have some value.
    • Oh, plus the whole saving the planet from destruction thing. I guess that might have some value.
      That depends heavily on durability, too, and the process required to make this stuff.
  • by BlueParrot ( 965239 ) on Sunday September 23, 2007 @03:43PM (#20721349)
    a)How long do they last
    b)How fragile are they
    c)What temperature ranges can they survive
    d)How strong light do they need
    e)What environmental impact will the cadmium have

    Sure, if it works all will be happy and dandy, but I somehow suspect there are some catches not mentioned here.
    • Found some. (Score:3, Insightful)

      by BlueParrot ( 965239 )
      From TFA:
      The cost to the consumer _could_ be as low as _$2_ per watt.

      Anybody spot the weasel word? Then there is the $2 cost to the consumer, rather than the $1 which is the cited production cost. Also, the article makes no mention of what levels of incoming radiation these numbers were calculated for. $1/W means something quite different in Egypt than it would mean in Sweden. Is the $2/W derived from the peak efficiency under ideal weather conditions, or is it the average over a year?

      Essentially, if you wa
    • by ahfoo ( 223186 ) on Sunday September 23, 2007 @04:15PM (#20721631) Journal
      Here in Taiwan, we just had the annual solar trade show which is becoming a really big deal on the silicon island. Solar has become a huge because it dovetails right in with other semi industry players that get put together in industrial parks.
              So this year there was a big dollar-per-watt announcement from Oerlikon. If you don't know who they are, they're a Swiss provider of turn-key thin film or amorphous silicon solar panel factories. They've got several partners in Taiwan already including, most recently, some of the large-scale optical media manufacturers who already use similar techniques and equipment and have some cash to invest.
              The local Oerlikon rep was saying that producers will be at sixty cents per watt within forty eight months and that this will mean actual product at the dollar a watt level. Hey, I'm just passing along what the sales rep said. Obviously he's got a reason to overstate his case, but that's what he claimed was coming down the piple.
              I think it's also worth noting that a former Slashdot sweetheart that went by the name of Spheral Solar has basically dropped off the map because they realized that amorphous silicon was going to take over.
              Oerlikon bought up Excimer laser of the UK last year. One of the repeated steps in doing thin film solar is laser etching.
              I'm not too sure about the tech being referred to in this piece, but dollar-a-watt PV, which is what the UN and other agencies have said is the tilting point where solar is cheaper than coal or natural gas, is already being spoken of at industry trade shows and shouldn't be seen as a wildly implausible announcement.
  • 10% - 15% is not high efficiency for photovoltaic panels, 30%+ is high efficiency.
  • Approvals (Score:3, Interesting)

    by Alioth ( 221270 ) <no@spam> on Sunday September 23, 2007 @03:45PM (#20721363) Journal
    Cadmium... so not RoHS compliant, so not saleable at all in Europe and many other parts of the world. Oh dear.

    I wonder if RoHS will be relaxed for solar energy?
  • $2/watt retail? I'm there. I'll take 5Kw worth of panels, a couple wind turbines, and backup diesel generator and the power company can kiss my big, white butt. Already have my battery boxes built, best start working on those wiring diagrams!

  • Interesting (Score:5, Informative)

    by m.dillon ( 147925 ) on Sunday September 23, 2007 @04:03PM (#20721523) Homepage
    The real question here is how will these panels stack up to current poly panels with regards to their life span? All solar panels degrade over time - that is, produce less power as they get older. Rule of thumb for a poly panel is around 25 years. While there are many types of panels only a few are actually in mass production and have the required life spans. If you are looking to install solar now, polycrystalline panels are what you want to get.

    1.5 to 2 KW worth of panels is enough to run a typical house unless you have a machine room. Even if you use more power then your panels can produce, it's actually all to the good because it means the panels are recovering the highest-tier electricity costs for you, dropping you down to a lower tier with your utility company.

    You don't want batteries unless you are off-grid, and most people will be on-grid. There are many grid-tie solutions available and costs have come down considerably over the years. Batteries are of course essential if you are off-grid but knowing the many hackers here I'm sure many of you would like to be able to disconnect from the utility completely, survive blackouts, and so forth... but generally speaking, the batteries and equipment required to do that adds a lot to the cost of the system and involve considerably more maintenance and worry.

    A straight grid-tie system is completely maintenance free. I literally have not had to touch my system since the day it was installed. I just pop into the garage and stare at the cumulative power display every so often :-) []

    • Re:Interesting (Score:5, Informative)

      by bcrowell ( 177657 ) on Sunday September 23, 2007 @06:07PM (#20722371) Homepage

      The real question here is how will these panels stack up to current poly panels with regards to their life span? All solar panels degrade over time - that is, produce less power as they get older. Rule of thumb for a poly panel is around 25 years.

      Like you, I have a residential grid-tied system. The panels cost roughly $5/kW, plus a similar amount for the inverter, installation, etc., and I decided it was a reasonable investment if the lifetime of the panels was 25 years. If the panels only cost $1/kW, then the whole thing would have been a reasonable investment even if the projected lifetime of the panels was 5 years. Actually I find it a little frightening to have so much of my money tied up in this physical object sitting on my roof. It's covered by insurance in case of an earthquake, etc., and by warranty under some other conditions, but in general, if someone offered me a system with much cheaper panels, and told me I might have to get them replaced more often, I would probably prefer that, because it would tie up less of my capital in the system.

      Even if you use more power then your panels can produce, it's actually all to the good because it means the panels are recovering the highest-tier electricity costs for you, dropping you down to a lower tier with your utility company.

      This may vary from place to place. I live in Southern California, and my electric company is SCE. The way the deal here works, it's a really bad idea to pay for a system that generates more in a year than you use in a year. SCE bills me yearly. If I generate a little less than I use, they send me a small bill at the end of the year, which is fine. (If you realize you're consistently generating less than you use, you can always add more panels later, assuming you have the roof space. You've already invested in the inverter, so it's not a big deal to add more capacity.) If I generate more than I use, then they don't send me a check, they just say, "Thanks for the free electricity." If I overproduce, it means I goofed big-time, because I spent more money than I needed to on my system, and it isn't returning any more on my investment than a smaller system would. Basically if you do things right, you end up with something that almost exactly covers your yearly electricity, and that means you couldn't care less what the rates are on your schedule (schedule D, TOU, whatever) -- when you pay zero, you don't care what rate you're paying at.

      • Re: (Score:3, Interesting)

        by Jeremi ( 14640 )
        If I generate more than I use, then they don't send me a check, they just say, "Thanks for the free electricity."

        That rule has always annoyed me, since it removes the incentive to use your roof's insolation to the extent possible. I wonder if there is some way around it, perhaps by going co-op with your neighbors (e.g. so that if you overproduce, your bill goes to zero and your neighbor's bill is reduced by the extra amount... then at the end of the year your neighbor send you a check for the difference, o

  • by cdn-programmer ( 468978 ) <> on Sunday September 23, 2007 @04:11PM (#20721587)
    The solar constant is about 1300 watts per square meter (in space). On earth the best you can hope for is about 1000 watts peak. So on average we will look at about say 50% of 50% and less on a cold winter day when we need both heating and more lighting. In fact on a winer day at about 51 degrees latitude we get about 8 hours of light and even then its less than 250 watts per square meter.

    If we take 10% of 250 we get 25 watts. This is about as much as a high efficiency mini florescent uses.

    To run a toaster we will need 40 square meters of solar panel and to roast a turkey and cook on top of the stove as well we look at 40 amps @ 240 volts (check your main panel folks) which is about 385 square meters at 25 watts per square meter.

    Thing is that we might want to roast the xmas turkey after dusk, so we better plan on batteries.

    A deep cycle 12 volt battery (lead acid) can be expected to hold 60 amp-hours.... at least this is what the Hawker batteries I use for my UPS system are rated for.

    12*60 = 720 watts hours. To roast the turkey say takes 4 hours at a draw of say 30% of 40 * 240 which is about 11,250 watt hours. So we need 15 batteries for this. Next if we draw them down any more than about 20% the number of cycles goes into the toilet so we'll need about 5x as many so we can draw each to about 20% of their max rating. We'll need 75 batteries.

    New these batteries cost more than $250 bux so that is a battery investment of $18,750.

    Clearly one will not be running an electric range off that solar system.

    I'm not scoffing at the idea. I think its good but one has to find a way to store that energy and perhaps the best use of it will be to create hydrogen.

    The thing is that sure it can feed into the grid during the day. All this does is put idle the current generating infrastructure and we still need that infrastructure for night operation. Of course it would save the fuel needed to operate the plant.

    But then what would we use the existing generating stations for when they are idle? Generating hydrogen?

    Somehow it doesn't make sense to burn fuel to create electricity to make hydrogen when we can simply for instance chemically take the Methane apart and get hydrogen that way.

    One really has to think about how this cheap solar technology fits into the full cycle of energy needs.

    Nevertheless I think it is good and maybe we should use it to pump water up hill. Then at night we can let the water flow back through the pump and turn it into a motor-generator. Batteries are just one way to store energy. It can be stored as compressed air, water at the top of a hill, chemically such as hydrogen gas... but it will need to be stored and in great quantities if this technology is going to go anywhere.

    Plants such as trees are another good solar collector. We tend not to use them. They are reasonably efficient and serve as their own battery system because if you need more heat you can chuck another log on the fire. Since most of us tend not to use the solar collectors mother nature already created for us, I suspect that there will be huge issues to overcome in order to deploy even cheap man-made ones.

    Now here is another thought. The best efficiency of these collectors is say 10%. If we capture the same energy for space heating our houses we can easily get over 80%. Yet, most of us do not even do this.

    A super heated house with R70 in the ceiling and R50 in the walls costs about $1 dollar per square foot of building envelope extra during construction. This will eliminate the vast majority of summer cooling and winter heating loads. Here in Calgary for instance a house like this does not need a furnace and we can have winter days that are 40 below for weeks on end. A house like this can get by with a nice fireplace and wood heat and will burn less than 1 cord of wood per year. That wood costs about $100 dollars.

    But, most of us don't even do this.

    I think solar is a great idea but a low
  • by Animats ( 122034 ) on Sunday September 23, 2007 @04:27PM (#20721709) Homepage

    OK, let's see if this is for real.

    First, the "story" is a regurgitated press release. [] For an more critical story by a local reporter, see "AVA Solar enters crowded field", by Tom Hacker [].

    The AVA Solar web site has almost no useful information. But they have a patent on the manufacturing process [], which discloses what they're trying to do. Among other things, the patent tells us that "AVA" stands for "Air-Vacuum-Air". The process is mostly conducted in a low grade vacuum, with some preprocessing in air before the vacuum chamber and some final steps after vacuum processing. The big deal is supposed to be that there's only one trip in and out of vacuum, which simplifies the production process. This patent was filed in 2000, so they've been working on this for a while now.

    They're trying to make cadmium-telluride solar cells, which aren't new. The new thing is making them with a continuous process, instead of in batches.

    AVA Solar has some job ads on Dice. [] They're looking for a plant manager, and on Dice they say "200+" employees, rather than the "500+" mentioned in the press release. AVA Solar doesn't seem to actually make anything yet, so they have to build and run a new kind of manufacturing plant of their own design without an organization experienced in doing that. That's hard.

    They're supposedly building a pilot plant, to be running by the end of 2007. So wait a few months. If that works, it's worth looking at them again.

  • by Whuffo ( 1043790 ) on Sunday September 23, 2007 @04:40PM (#20721789) Homepage Journal
    Assuming this actually turns into something that you can really buy - and it actually is 15% efficient for $1 per watt then this should be the "push" that starts the large-scale conversion of homes and businesses to solar electric power.

    More is needed, though - even with cheap and plentiful solar cells you're still up against some physical limits. You've only got so many square feet of southern exposure you can put panels on - and it's not anywhere near enough to support your current level of electric power consumption. Keep in mind that solar panels are rated at "full sun" and in the middle of winter you'll be lucky to get 10% of that on a bright sunny day.

    So a good place to start is to find ways to reduce your power consumption. Not "feel good" little reductions, but serious cutbacks. Think about things like skylights in kitchens / bathrooms (free lighting), better insulation and weather stripping, and even some automatic controls on things like lighting, heating, etc. - these will remember to shut off the lights, turn down the heat, etc. even when you forget.

    Pick up a small watt meter; something like the "Kill a Watt" can help you discover where the power is going. You'll find that a lot of it is pure waste and easily eliminated. Use task lighting instead of lighting up the whole room / house, look for more ways to reduce consumption.

    You'll have to make some concessions and adjustments to live a low power consumption lifestyle - it's up to you to determine how far you can comfortably go. But if you can cut your consumption by 50% or more (very possible) then you're getting to the point where those solar panels can supply enough power to keep you going.

    And you're going to need some kind of backup generation for those dark and dreary winter days. House sized generators are usually NOT cost effective, battery banks are expensive and troublesome. Grid-tied systems are clean and easy - but get the facts from your local utility before going this way. Some are very reasonable, some want to pay you their "generated cost" (less than wholesale) for the power you put into the grid - but charge you peak rate for the power you pull from the grid. This can wipe out your solar savings; be careful. Choose which ever of these best fits your needs and hope you never need to use it.

  • by cdn-programmer ( 468978 ) <> on Sunday September 23, 2007 @06:25PM (#20722495)
    A 2 foot by 2 foot chunk of window glass in the store is $17.40 at Rona. A square meter is 10.76 square feet. So a 1 meter square piece of glass would cost $46.82 at these rates.

    Even the cheapest solar cell should be expected to cost more than plain glass since it includes at a minimum plain glass.


    Solar constant is 1300 watts per square meter in space and max 1000 on the surface of the earth.

    One can expect on average 12 hours of darkness. Then we can expect only 50% of this max because most of the time its not high noon. One actually has to integrate the sin curve.

    So we can say 12 hours at 500 watts average maximum collection and at best we can hope for about 50% of this. This 50% discount takes into account rainy days and snow blowing on it and maybe it gets a little dirty because people don't wash it often enough.... there are lots of things that can go wrong here. So I pick 50% out of the air as a practical fudge factor to convert to what is theoretically possible to what one might expect.

    This is 3000 watt hours per day falling on the panel in a useful way, and the efficiency of the panel is say 10-13% so I'll use 10%. We can expect to get say 300 watt hours per day per square meter. This is 0.3 kwh which in worth say about 3 cents at a rate of 10 cents per kwh. This is still 25 watts per square meter for 12 hours and this is what a mini florescent draws.

    But from the article - they say $1 per watt so I assume they mean per watt peak capacity.

    This would be 100 watts per square meter since we have 10% of 1000 and the 1000 is peak. The duty cycle is at best 1/4 of this. Nevertheless, $1 per watt * 100 watts is $100 per square meter.

    Thing is $100 per square meter is only 2x the cost of a plain glass windowpane so its actually unreasonable to expect they will be able to sell these panels at anywhere near 2x the cost of plain glass. A complete window assembly is in the order of a few $100 bux. Maybe we get the complete panel retailing at $200.

    What should we expect to really get out of a $200 panel in terms of energy?

    At best, 25% of max and this is about 25 watts per square meter and this is over 12 hours. Hence one should expect the thing to capture at most say 300 watt hours per day.

    As I calculated before this is about 0.3 kwh = 3 cents worth of power. $0.03 * 365 = $10.90

    Invest say $200 in a panel when it retails and get $10 per year from it in electricity. This is a 20 year pay back not counting installation, maintenance, and so forth. At a 5% interest rate (cost of capital) it has a ZERO Return on Investment (ROI).

    Now the real issue. Suppose everyone does this. It will have the effect of destabilizing the grid because it puts the power company in the position of standing by ready to supply energy at night and when the sun doesn't shine but meanwhile when the sun is shinning their expensive infrastructure sits idle. So long before this gets deployed the rules get rewritten.

    The thing is that we can already capture solar energy passively and build houses that will save way more than $1000 per year in energy and do this for a capital investment of less than $5,000. All we need to do is put R50 and R70 in the walls and ceilings. We can do a LOT more than this. To capture say $1000 per year with say these high efficiency panels will cost 100x$200 bux = $20,000 of capital and this does not include the control systems.
    • Re: (Score:3, Informative)

      by drew ( 2081 )
      $1/W to manufacture. The actual cost to the consumer would be quite a bit higher (probably at least double), so your comparison to the price of a piece of glass in a store is not exactly meaningful.

Disks travel in packs.