You're likely going to require two or maybe three 2500 watt heating elements.
https://www.ebay.com/itm/223969713822
https://www.huoltopalvelu.com/Elect...shing-machine-heater-2500W?PageSpeed=noscript
Much is going to depend upon programming available for wash cycles.
That is if max wash cycle is say 12 minutes you're going to need lots of power to heat water quickly.
Then there is will you be doing starting from cold (expensive and time consuming) or beginning with hot water and boosting it up to 140F or above.
Most commercial laundries don't bother with starting from cold, but have hot water from tap and use heaters to boost temps to desired range.
Where available commercial/industrial laundries will go with steam because it's usually faster and cheaper. Of course such laundries are also using steam for ironers, dryers, ironing, steam tunnel finishers, so they have other reasons to have onsite boilers.
Contrary to what many would believe commercial/industrial washers actually inject steam into wash water for heating. In past this was done manually by opening and closing steam valves. Modern machines however have built in controls to operate said steam valves.
One consequence of injecting steam is water levels are slightly below what ought otherwise to be, this is to take into account steam injected into washer will condense back into water, which in turn will raise level.