Depends on what are you manufacturing. 200 watts from square meter roof is doable. 3x3 meter is about right space for a single machine with all the enclosures,

Depends on what are you manufacturing. 200 watts from square meter roof is doable. 3x3 meter is about right space for a single machine with all the enclosures, tables, etc (in Europe). The average sized machines can be used with single phase allowing 3,6 kW power consumption. Half of it comes from solar panels. Halving power consumption is good imho. This math does not work for steel factory. The math is much better for assembly line type plant where only power tools <1 kW are used.