This true on any planet with any constant rotation relative to the star. No matter the location on the planet or it's axis inclination, or whether the planet wobbles on it's axis.
Generally topgraphy has a more exaggerated affect as one moves poleward. And the atmosphere with block more radiation as one goes towards the poles.

But with longer day, one would a longer block of time in which power could come from solar panels. But more important then perhaps this minor matter, would whatever affect a longer day would have on average cloud cover.

As one example, in coastal regions in Califorina, one has a cloud cover which burns off in the morning or even late as afternoon, if there was a longer daylight, could this could burn off well before noon.
But the question is globally would the result of a longer day cause more cloud cover or less. And I guess in terms of solar power, would cloud cover be less in tropics and regions near the tropics [such as the "sunbelt" in America].