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JA Solar Percium or SolarWorld installation? Plus "efficiency" question.

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  • JA Solar Percium or SolarWorld installation? Plus "efficiency" question.

    I have been looking into having a solar PV system installed, and have narrowed my surveys and quotes down to two companies.

    Both companies say that the roof space, based on making measurements from below, looks like we should be getting a 12 panel installation. We live in a terraced house, and while there is almost enough space for an extra row to allow for 15 panels, there is quite a high chance that this would mean the edging would encroach on our neighbours' roofs slightly, so we should be prepared to have just 12 panels.

    Company 1 initially proposed:
    12 x SolarWorld Sunmodule Plus 250W poly (blue) panels, total all inclusive cost 5500 UKP.

    This company only works with SolarWorld panels, so wouldn't be able to spec another manufacturer. I asked the representative if they supply a panel with a higher wattage, and she said yes they do have a 280W panel, which she would also quote me for, but her recommendation is the 250W panel because I would find them to be much more efficient.

    This statement doesn't make sense to me. I can appreciate that different panels from the same manufacturer will vary slightly in efficiency, but surely efficiency is taken into account in order to calculate the 250W/280W figure? I understand (I think) that this number is expected peak output, and that different panels may perform better in low light conditions etc, but I would have expected a 280W panel from the same company to give me roughly the proportional increase in output that those numbers suggest. Anyway, the second quote she sent me was:

    12 x SolarWorld Sunmodule SW 280W mono panels, total all inclusive cost 5900 UKP.

    Company 2 has provided me a quote of:
    12 x JA Solar 285W Percium black frame, total installation cost 6283 UKP.

    The representative from company 2 was very keen to stress that these are the new Percium panels, released this year, and his company is one of the first to have them in the UK. They are apparently 17.43% efficient with cell efficiency of "an amazing" 20.4%. He also said, once I'd told him that my other proposal was with SolarWorld panels, that although SolarWorld make good panels, "everyone in the industry" knows that SolarWorld are financially unstable, so I could end up with panels that are not guaranteed if SolarWorld go under. He said company 1 would be going for these because they are cheap, and that he would never supply them.

    So, everything else being equal, which of these three proposals looks best? Is the "amazing efficiency" of the JA Solar worth the extra money, or am I not really going to notice much difference compared to the 280W SolarWorld? And is there any truth in the 280W/250W efficiency statement? And should I be worried about SolarWorld's supposed financial instability?

    Desperate for advice from someone who doesn't have a financial incentive for telling me certain things!

    Many thanks!

  • #2
    Many of your questions about the difference between standard and premium modules are discussed in other threads that you might find helpful to read.

    This statement doesn't make sense to me. I can appreciate that different panels from the same manufacturer will vary slightly in efficiency, but surely efficiency is taken into account in order to calculate the 250W/280W figure?
    Yes, if both the 250 W and 280 W panels are the same size, then the 280 W panel must be more efficient. Under standard test conditions, they would both be exposed to the same amount of sunlight.

    With a data sheet, it might be possible to figure out how much improvement in low light conditions there might be. To some extent, the inverter you choose matters as well. Chances are good it won't amount to much difference.

    When comparing systems, you might find it helpful to break it down into price per watt. For example:

    SW 250: 5500 / (12 x 250) =
    SW 280: 5900 / (12 x 280) =
    JA 285: 6283 / (12 x 285) =

    12 panels of 250 watt will clearly generate less than 12 panels of 285 W. How much of your electric bill are you trying to replace? Are there other installers from whom you can get quotes to see how they compare?
    CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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    • #3
      That's the question that we all must ponder when dealing with space issues. If your goal is the most kw in the small space you have then buy the higher rated ja panels. There are higher rated ones avail. 300watts and 345 if you continue to look. If the solar world meet your needs then you may be able to find cheaper 250s. With that said, her saying the 250s were more efficient sounds silly to me and I would personally be wary.

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      • #4
        Both salesmen seem to talk a lot more than the knowledge they have. Might try more parties - someone must know what they are talking about.
        [SIGPIC][/SIGPIC]

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