Assuming you are generating electricity for the sole use of mining:-

The general understanding is that 7 hours of sunshine alone is not enough to offset your usage in such a way that the solar side of the system will ROI not in 3years unless you have a grid-tie setup. That money could infact be invested in more energy efficient (hence expensive) miners. So do your math carefully considering your electricity provider's policies around grid-tie.

But if you are a solar farm and want to mine, that's a different aspect altogether - which I believe is not the case.