Power wash and pressure washing is such a common thing now, apart from pressure washers there is specific equipment now which is just used for pressure washing and similarly detergent which is used in power wash is also specifically designed for this purpose, it has the right mix of chemicals which works perfectly with high pressure and heated water so you cannot use just any soap and hope for the best, remember that any soap or detergent is mixture of chemicals and every different sort of chemical would have an impact on the surface, choosing the right soap at the right surface would only bring better results.
With green cleaning now being the most sought after type of cleaning you should select biodegradable soap for pressure washing your house because that is best for your own and your family’s safety but it has the least amount of environmental footprint and that is what every responsible human being should do, detergent is just any cleaning agent and you should select from a wide range, in the initial days of power wash even the professionals would not give much attention to selecting the right detergent or soap, but as competition grew and since there is so much more focus on saving the environment because we have already done some grave damage to it, the professionals would ask specific questions regarding the type of service you need and what the surfaces include and select the right type of pressure washing soap.
Apart from the environmental footprint and the safety of the surface it is also important to remember that the power washer would not bear just any sort of soap, only the ones which are biodegradable and specifically designed for power washing work best in such situation.