How to determine the nameplate capacity when you have the demand?

I am using Plant Simulation to model a manufacturing system and got its monthly demand in KWh. I want the PV system to provide me with this monthly energy output. I dont want to play with the nameplate capacity to see everytime I match that demand. Is there an accurate way to exactly get the nameplate capacity for the corresponding energy output KWh?

Thank you.

It may not be an accurate method but it is good enough for a first cut.

We have to do that type of analysis all the time since we look at the technical feasibility of rooftop PV that is constrained by rooftop obstructions and such. The problem with determining the amount of capacity that you can fit on a rooftop is only half the story since you also don't want to oversize your system to your load. This problem in exacerbated in utility territories where there is no their are special restrictions placed on the amount of PV a customer is allowed to interconnect in net-metering policies. The policies generally restrict the PV capacity to some percentage of of the building load generally anywhere from 80%-130% of the building load.

That being said. What we do is determine the capacity factor of the site and then use that to back into the nameplate capacity. The formulas we use is: Nameplate Capacity (kW) = (Percent of Building Load * Annual Building Load (kWh)) / (8760 * Capacity Factor ).

Hope that helps.