So they can substitute for conventional tinted glass skylights and windows. It results in a maximum volts-amp product. At maximum sunlight, the bottom end point shifts right, and the top end point shifts down a bit. It adds another input power source. When it exceeds loads, it can reverse utility power.
Some inverters turn off solar powered output when grid power is off.
So then you have no power when the grid is down. We can do far better. So total current sum is I max and it is constant. Industrial buildings usually have significant loads from 3-phase machines. A 3-phase inverter to power them would likewise draw constant DC current, without significant ripple.