These days it's becoming common for solar to be installed at "non-optimal" angles, designed to maximize the amount of solar produced at the start and end of the day, rather than the middle of the day where there's already more than enough power.

Mining Bitcoin with solar is kinda similar: we're finding a way to maximize the amount of solar available during non-peak-production. With Bitcoin, you do that by finding an economic use-case for the excess peak power, allowing you to be able to afford to install more solar overall, and thus have more energy available at non-peak-production times.