It's not 3.5kW. It's during the day more like 9 average. In summer, lots more than that. If the factory shuts down during the night, then in summer, it is considerably better than 3.5kW. (but plastering those same solar panels onto the roof would work considerably better still)
30,000 KWh over a year (8760 Hrs) is an AVERAGE of 3.42 Kw. May be PEAK of 9Kw (We don't know, all we know is it 30MWh/yr).