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  • Optimizers for modules connected in series.

    I heard they are helping with shading, keeping currents equal or something, but that's only what I heard. Does anybody know how they work?
    Utility interactive system with string inverters

  • #2
    Originally posted by abelov1984 View Post
    I heard they are helping with shading, keeping currents equal or something, but that's only what I heard. Does anybody know how they work?
    Utility interactive system with string inverters
    Most optimizers are either Tigo or SolarEdge. SolarEdge uses its own inverter, Tigo can work with any inverter. If it is SolarEdge that you are talking about, they have a white paper that does a good job explaining what they are doing. The total voltage in the string is held constant, and each optimizer contributes whatever power it can from its panel.
    CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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    • #3
      Optimizers with full shading

      I looked at the white paper form Solar Edge where they evaluate partial shading scenario, but what happens when you have full shading on one or more panels in a string?

      My recent experience with Tigo shows that it depends upon which panel of the 2 attached to the maximizer is effected. Tigo are a dual maximize meaning that one Tigo module controls 2 PV panels. There is a A and B channel. The Tigo installation literature does not tell you, but the Tigo is powered only from the A channel so if the panel on the A channel is completely blocked the maximizer is not functioning and this impacts the entire string. I learned about this due to the heavy snow cover that we had this winter. We had selected Tigo as my roof area are very broken up. I have sections that have SE and SW exposures as well as dormers creating different slopes. Main roofs are 40 degrees and dormers are 20 degrees. The 40 degree roofs clear the snow very quickly whereas the 20 degree roofs have stayed snow covered until now. Some of my strings are on both the 40 degree roofs and the 20 degree roofs and some of the A channel panels for these strings were on the 20 degree roofs. I noted that I had strings that were producing consistent power and that I had panels on the same roof that were not. The poor performing panels were on strings that crossed to roofs with heavy roofs snow cover. B channel panels that should be producing a lot of power were not because their A channel counterpart was blocked.

      We learned that with Tigo that the string design needs to take into consideration potential blocking and to set up the A channel connection on the panel that has the greatest probability of being powered.

      We reconfigured my strings to put the A channel on the steeper roofs. I will have panels and one complete string that will not produce power when we have snow cover like we had this winter, but should have it configured as best as it can be. Of course we have no snow cover now so we may have to test it using blankets or wait until next winter.

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      • #4
        Originally posted by graeckm View Post
        I looked at the white paper form Solar Edge where they evaluate partial shading scenario, but what happens when you have full shading on one or more panels in a string?
        Solaredge is at its best when some panels, but not all, are in full shade. It allows those shaded panels to operate at their maximum potential (as documented by the I-V curve with traces showing the response to different level of irradiance), while allowing the panels in full sun to continue to fully produce. In a normal series string inverter, the fully shaded panels force the inverter to find a non-optimum power point that reduces what the unshaded panels might otherwise produce.

        When a panel is partially shaded, an optimizer's results are more mixed, it is easy to lose 1/3 or 2/3 of the panel to the bypass diodes, and there is nothing an optimizer (or microinverter) can do about that.
        CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

        Comment


        • #5
          Originally posted by graeckm View Post
          I looked at the white paper form Solar Edge where they evaluate partial shading scenario, but what happens when you have full shading on one or more panels in a string?

          My recent experience with Tigo shows that it depends upon which panel of the 2 attached to the maximizer is effected. Tigo are a dual maximize meaning that one Tigo module controls 2 PV panels. There is a A and B channel. The Tigo installation literature does not tell you, but the Tigo is powered only from the A channel so if the panel on the A channel is completely blocked the maximizer is not functioning and this impacts the entire string. I learned about this due to the heavy snow cover that we had this winter. We had selected Tigo as my roof area are very broken up. I have sections that have SE and SW exposures as well as dormers creating different slopes. Main roofs are 40 degrees and dormers are 20 degrees. The 40 degree roofs clear the snow very quickly whereas the 20 degree roofs have stayed snow covered until now. Some of my strings are on both the 40 degree roofs and the 20 degree roofs and some of the A channel panels for these strings were on the 20 degree roofs. I noted that I had strings that were producing consistent power and that I had panels on the same roof that were not. The poor performing panels were on strings that crossed to roofs with heavy roofs snow cover. B channel panels that should be producing a lot of power were not because their A channel counterpart was blocked.

          We learned that with Tigo that the string design needs to take into consideration potential blocking and to set up the A channel connection on the panel that has the greatest probability of being powered.

          We reconfigured my strings to put the A channel on the steeper roofs. I will have panels and one complete string that will not produce power when we have snow cover like we had this winter, but should have it configured as best as it can be. Of course we have no snow cover now so we may have to test it using blankets or wait until next winter.
          You also may want to do some research on snow removal practices and equipment. Even if you rewire there is always a possibility the A channel panel gets less sun due to snow cover.

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