High radiation but Low Power Generation

I’m simulating solar power generation for PV Louver.

I’m only checking the power generation at a certain point in time.

As I expected, the power generation of the top slat should be higher than that of any slat, but the result was not.

So when I checked the amount of solar radiation given to each slat, I found that the top slat had a lot of solar radiation as I expected.

As a result, we found that the trend of solar radiation and the trend of power generation do not match.

May I know why?

Thank you for your answers.
(I have attached a file.)
PV Louver.gh (1.5 MB)