[int_19h]

There's also the angle of the sun to consider, it changes quite a bit in higher latitudes between summer and winter so if you want maximum efficiency you need to tilt the cells accordingly. But I don't think most residential solar does that.

[Marsymars]

The way the math works for grid-connected residential here, if you're not adjusting the angle, between seasons, you'd be best off leaving it at the optimal winter angle all year, which would minimize the difference between peak/trough generation.