I have this design using SPV1040
It uses SM102K06L solar panels, that have Vmpp = 3.35V, Impp = 0.406 A (Pmpp = 1.36W). The output must charge a 4.2 Li-Ion battery.
At direct sunlight with one panel, I am measuring 0.39 A, and 1.81 V (voltage measurements in parallel with panel, current measurement in series with panel). That's just 0.7 W, half of what I expected.
The interesting thing is that if I connect TWO of these panels in PARALLEL, I get 0.7 A and 3.37 V. That's 2.36 W, much closer to the 1.36 * 2 = 2.72 W that I would expect.
Why could the single panel configuration having so poor performance? Is the SPV1040 chip failing to track the maximum power point in this scenario?
EDIT: Forgot to add that when testing the two parallel panels configuration, I lowered Rs to 75 milliohm, in order to achieve a higher output current.
