I think the clear gelcoat (and textured gelcoat even more so) may cut the output more than you would expect. I say this because I talked to the architect of the local botanical gardens' big addition, and he explained that they had to use single-glazed glass instead of double-glazed because the extra layer of glazing would have meant that all the plants would starve to death in the winter. Who would have thought a layer of glass would substantially reduce insolation?
Not to say that it's a bad idea, you just have to overbuild the capacity. Pretty cool, imo.
I tested the change in output before I went ahead. It was not measurable with my voltmeter. The reason is that there is no air between the gelcoat and the solar cell. If there had been, it would have created specular reflection and a loss. However, the addition of too much blue pearl did lower the output a bit, I have yet to measure how much.