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Questions about SolarEdge inverter for 9.9kW system

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  • Questions about SolarEdge inverter for 9.9kW system

    I have a quote for a system with 36 SolarWorld 275W panels with SolarEdge OP300-MV optimizers and SE7600A-US inverter.
    The system has a nameplate output of 9.9 kW STC and the inverter has a recommended max DC power input of 9.5 kW STC.

    The installer said the 7600 inverter would work well with the 36 panels because they won't produce 9.9kW in real world conditions.
    I tried modelling the system with the 2014.9.30 version of NREL's SAM, which warned that the inverter would clip for about 100 hours during the spring.

    Questions:
    Is it OK to use the SE7600A inverter in 9.9 kW nameplate system? Or is it better to use a larger inverter or even 2 smaller inverters?

    Are the SolarEdge OP300-MV optimizers and SE-7600A-US inverter good choices?

    Also, how loud are the cooling fans in the SE7600A and SE10000A?

  • #2
    Hi Apollo - Welcome to Solar Panel Talk!

    To reply to your post it would help the guys if they know your general location - temp makes a difference.
    [SIGPIC][/SIGPIC]

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    • #3
      The installation is near Boston, MA.

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      • #4
        Originally posted by apollo100 View Post
        I have a quote for a system with 36 SolarWorld 275W panels with SolarEdge OP300-MV optimizers and SE7600A-US inverter.
        The system has a nameplate output of 9.9 kW STC and the inverter has a recommended max DC power input of 9.5 kW STC.

        The installer said the 7600 inverter would work well with the 36 panels because they won't produce 9.9kW in real world conditions.
        I tried modelling the system with the 2014.9.30 version of NREL's SAM, which warned that the inverter would clip for about 100 hours during the spring.

        Questions:
        Is it OK to use the SE7600A inverter in 9.9 kW nameplate system? Or is it better to use a larger inverter or even 2 smaller inverters?

        Are the SolarEdge OP300-MV optimizers and SE-7600A-US inverter good choices?

        Also, how loud are the cooling fans in the SE7600A and SE10000A?
        100 hours clipping doesn't sound like you'll be missing much power. If you are comfortable with SAM, try modelling it with the 7600, and then with the next size up. I just took a stab with it, and found that there was only 0.6% gain (<100 kWh) by eliminating the clipping. As the panels degrade, that will be even less each year.

        Using SolarEdge's own design software, it suggests the difference between the 7600A and the 10000A is more like 175 kWh. I would guess that works out to about $35 worth of clipped electricity in the first year, and less each year after that. It looks like the difference in price (per one online shop) is only around $100 to go from the 7600A to the 10000A, so really, either one is probably going to net you the same value.

        There might be installation or permitting issues that would come into play if you choose an inverter capable of supplying 10 kW. You could weigh that against possible benefit to reliability that operating the 10000A with some overhead might bring.

        In any case, why are they choosing the OP300-MV optimizers, instead of the newer P300's?
        Last edited by sensij; 11-10-2014, 02:29 AM. Reason: Edit, updated SolarEdge simulation results.
        CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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        • #5
          Originally posted by sensij View Post
          You could weigh that against possible benefit to reliability that operating the 10000A with some overhead might bring.
          I agree with Sensij, I would be more concerned with reliability implications from operating the 7600 inverter at high capacity than clipping <$50 of electricity.

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          • #6
            Originally posted by subdriver97 View Post
            I agree with Sensij, I would be more concerned with reliability implications from operating the 7600 inverter at high capacity than clipping <$50 of electricity.
            I think he meant that operating a operating an inverter close to maximum is more economical than operating well under - the additional overhead can be substantial.
            [SIGPIC][/SIGPIC]

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            • #7
              Originally posted by russ View Post
              I think he meant that operating a operating an inverter close to maximum is more economical than operating well under - the additional overhead can be substantial.
              Could you elaborate on this? Are inverters less efficient at energy conversion at capacities lower than full?

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              • #8
                Originally posted by sensij View Post
                There might be installation or permitting issues that would come into play if you choose an inverter capable of supplying 10 kW. You could weigh that against possible benefit to reliability that operating the 10000A with some overhead might bring.

                In any case, why are they choosing the OP300-MV optimizers, instead of the newer P300's?
                The efficiency curves for the 7600A and 10000A look similar so the efficiencies of both should be fairly close when the 7600A is near 100% rated output vs. when the 10000A is near 80%, right?
                Won't the 7600A run hotter at near 100% rated output compared with the 10000A at the lower % rated output? If so, will the higher internal temperature cause the 7600A to be less reliable?

                The inverter will be in the basement next to the electrical panel. How loud are the internal fans of the 2 models?

                BTW, they will be using the P300.

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                • #9
                  Originally posted by apollo100 View Post
                  The efficiency curves for the 7600A and 10000A look similar so the efficiencies of both should be fairly close when the 7600A is near 100% rated output vs. when the 10000A is near 80%, right?
                  I ran a google search on "SolarEdge Inverter Efficiency Curve" but all I could turn up was the data sheet that doesn't show the curve or the three phase curve. Where can I find the single phase curve. Interested because I'd like to have some room to grow my system.

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                  • #10
                    Originally posted by apollo100 View Post
                    The efficiency curves for the 7600A and 10000A look similar so the efficiencies of both should be fairly close when the 7600A is near 100% rated output vs. when the 10000A is near 80%, right?
                    Won't the 7600A run hotter at near 100% rated output compared with the 10000A at the lower % rated output? If so, will the higher internal temperature cause the 7600A to be less reliable?

                    The inverter will be in the basement next to the electrical panel. How loud are the internal fans of the 2 models?

                    BTW, they will be using the P300.

                    SolarEdge writes about the tradeoffs to oversizing in a recent whitepaper. They discuss to potential for shortening the life due to over working it, but also the benefit of better low light performance. For Boston area, they are fine with the 7600A with 9.9 kW of panels. For San Diego, it wouldn't be allowed.
                    CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

                    Comment

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