I plan on having the following array in my system:

Screenshot of solar array

Vmpp voltage at max. power point for each cell is 1.67 V

Impp current at max. power point is 18.4 mA

As the number of cells in the right "Parallel String" is greater than the one on the left, is it ok to assume that the final array Impp current will be somewhere around 92 mA (18.4 mA * 5) and the Vmapp voltage will be 3.34 V (1.67 V * 2,) or do I need to use the parallel string with less cells for this calculation?

I need at least two cells in series to have the voltage for the SPV1040 MPPT IC and would like to use all available space on the board, this is why I have a maximum of 9 cells.

EDIT: Here is the link for the solar cell's datasheet

  • 5
    \$\begingroup\$ This is ineffcient. Suppose each cell wants to output 1 A. Then the circuit of SC1,3,5,7 will output 4 A. The circuit of SC2,4,6,8,9 will try to output 5 A but they cannot, they will be forced to 4 A by the other circuit. It will be more efficient to make sets of 3 in parallel and connect those 3 sets in series. Then all cells can output their full 1 A. My 1 A is just an example, feel free to replace by 18.4 mA. \$\endgroup\$ Sep 30, 2021 at 14:16
  • 1
    \$\begingroup\$ The smallest solar panel I heave ever seen is 2V on my solar garden lights. It has four 0.5V solar cells in series on one panel. Maybe you have nine of these 2V solar panels that you say are cells. Solar panels with ten cells in series making 5V are available. Wouldn't that be smaller than many of your separately packaged cells? \$\endgroup\$
    – Audioguru
    Sep 30, 2021 at 14:35
  • 1
    \$\begingroup\$ 3 strings of 3 cells ( or even 9 cells in series) and a buck converter, would be better. (Also, what kind of cell emits 1.67V? I suspect it's already 3 or 4 cells in series, but you should have linked its datasheet.) \$\endgroup\$
    – user16324
    Sep 30, 2021 at 15:07
  • 3
    \$\begingroup\$ What prevents you from putting them all in parallel and boost from there or all in series and buck from there? Assuming a suitable IC choice. Optimizing the panel instead of picking and IC and let the panel suffer. \$\endgroup\$
    – winny
    Sep 30, 2021 at 15:53
  • 1
    \$\begingroup\$ @winny Unless I'm missing something, it seems like the SPV1040 is a suitable choice for boosting all 9 modules in parallel! \$\endgroup\$
    – Theodore
    Sep 30, 2021 at 16:12

1 Answer 1


I believe it would be (18.4 mA*4) i.e the total current from left side and voltage would be 3.34 V. In series connection of mismatched current and voltage ratings modules, the minimum current of the module will come into effect while the voltage of each module adds up. Similarly, in parallel connection, minimum voltage would come into effect while current of each module adds up.

Let me know if I’m wrong.


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