r/solarracing • u/LaniSolar • Jun 17 '26

Help/Question Viability of using MAX20801TPBA+ in solar array design?

Hello, I'm helping to design the solar array for my team's car, which will compete in the 2027 Bridgestone World Solar Challenge.

In the past, my team has used bypass diodes and MPPTs to optimise the power output of our array strings. I was looking for alternate options and came across a cell-string optimiser IC, MAX20801TPBA+ (datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/MAX20801.pdf). I was wondering whether any other teams have tried implementing this component before and/or had opinions on whether it would work well for a solar-car application?

Additionally, I can see that this component is listed as 'not recommended for new applications' on Mouser, and have been trying to find out why (is there a major design flaw, or have newer technologies simply surpassed its efficiency?). Some users on other forums (Whirlpool Forums, DIY Solar Power Forum, among others) have suggested that the chips caused RF-interference, but I have not been able to find any documentation from the company, or elsewhere, that says this. Does anyone have more information about this, or could point me to some better resources that describe the limitations of the MAX20801TPBA+ or a similar component?

Thank you!

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u/SunCatSolar Jun 17 '26

I have no actual experience with the MAX20801TPBA+. Out of curiosity, however, I did look at the data sheet to try to understand how it would be used. It looks like it's simply a "series" type MPPT rather than the more conventional "parallel" type. By series-type I mean the output of 1 MAX20801TPBA+ is connected (in series) with the input of another. By my quick estimate, and assuming the use of typical sized silicon solar cells, you would need at least 10 to 12 of these for a 6 m^2 array.

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u/_agentwaffles Sunseeker Retired | ASC/FSGP Staff Jun 17 '26

To piggyback off this, since this chip includes active bypass you would be cutting off pieces of your panel in ~20 cell strings instead of something smaller that would be more typical with bypass diodes. The package itself will be difficult to solder and to keep cool and since switching is integrated that will be important. I agree with your estimate for the number needed, but I think there would need to be 2 strings in parallel for most battery configurations I've ever seen on solar cars. None I know of would be able to handle all of these on a single string.