My next brewery plan will be able to handle 25 gallons in the MLT for Stouts plus have 15 gallons in the corny's after fermenting. The ability to handle a big grain bill with 15 gaoolon on down to 5 gallon batches. Why limit myself from the start of the build?
I was planning on two 5.5KW elements in all three keggles. Start heating with 11KW, near the set temp switch over from the HLT to the MLT and repeat again at 11KW of heating. Once the MLT is near strike temp switch to one 5.5KW element in the HLT and MLT each to come up and maintain their set temps. This all controlled by the BCS460 unit that can handle up to 6 heating outputs signals to the SSRD's. This was my plan with all the keggles insulated for quick heating with 11KW the maximum heating at any given time not counting the pump, BCS unit and any lighting controls of additional wattage. The same with the boil keggle starting with 11KW then maintain the boil with one 5.5KW element. After going thru a few friends propane, natural gas as well underpowered electric systems I chose to go with higher wattages. Waiting for long temp increases isn't what I call a fun brew day with low wattage element systems I want to brew not watch the sun cross the sky waiting for temps to rise.
I already have the free cords and the power so why not? Better to have extra power than under powered and unhappy with your time and investment brew project. JMO here.