Sounds like a cool project. Generally when there aren't any features, like there would be in the presence of a nasty glare, that part of the image won't be used for in the model texturing.
As long as you get a couple clear shots of everything, it should be OK. A cloudy day is going to be your best bet though.
Depending on what kind of solar array it is and how they are mounted, you might be able to find a point in the day where it won't make much of a difference. This is one of the rare instances where mapping late in the day might be preferable.