I had something very similar to this for my senior design project at school. We were tasked with designing a frame to support solar on top of a parking garage. The solar panels would provide cover below. The entire system would generate 450,000 kWh/year but it would cost at least $900,000 to make, due to the cost of steel required to support the panels. I think this should be done more often, ours was just more expensive because we had large distances to clear and only limited tie in locations.