Some curiosities about optimizers that I can't seem to find info on

Matthew Hebb

• 2021年10月24日 00:05
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I see that the optimizers are described as allowing a bypass tunnel to keep one panel from dragging the rest down. This works for shading but their must be more for mismatched panels, it says the optimizers runs from 0volts to the VOC. So if the panels are mismatched slightly is it just forcing thoes panels to stay a bit above their mppt voltage in order to match the rest of the strings voltage? Also it mentions different length strings as well which makes me wonder how that would work as it would have to boost the output well above the panels VOC to make the strings work. 

 

I guess to put it simply is this just only acting as a MPPT per panel or does this actually have  boost/buck electronics in it as well to help with the mismatches and shading? 

1

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  Gary Hethcoat

  • 2021年10月26日 17:11

  Hi Matthew,

  Tigo is a buck-only architecture.  Our optimizers will buck (lower voltage and boost current) on underperforming PV modules.  This is the same action for any kind of mismatch in the string(s).  We try to keep the current the same across the string by bucking.  For the case you mention where you have different length strings in parallel, say a string of 12 and a string of 10 in parallel.  If you have optimizers on all panels, the optimizers on the longer string will buck the voltage down to match the other string, and you will get the full power available due to the boosted current on the longer string.

  We have a white paper on Optimization in the "Technical Documentation" section of our Downloads area:

  • Whitepaper – Maximizing Energy Harvest

  • DC Optimization with Tigo will normally allow you to reclaim an average of 36% of power lost due to mismatch.  Mismatch can be caused by shading, soiling, clouds, snow and differential degradation, among other things.  So for example, if you are losing 100 kWH of energy to mismatch in a year, you can expect to gain about 36 kWH of that energy back through optimization.  That 36% figure comes from an NREL paper, “Partial Shading Assessment of Photovoltaic Installations via Module-Level Monitoring”

  See also:

  • Design and Overcoming Mismatch
  • “Uneven Strings”
  • “Different Orientations”
  • “Mix and Match Different PV Module Types”

  Hope this helps!

  Gary

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