Even though that joke is wrong… graphite breaks off and is a fire hazard… in this case using dispensers seem to eliminate this problem and the massive apparatus used to support it.
Maybe Hilton guests just really like their bar soap? How many people don’t bring their own anyway?
Another idea: assuming you have an electric water heater, when your battery has been fully charged and you still have excess generation, use the excess to heat your water heater up to a very high temperature like 80 degrees C. You'll then be using very little hot water in the evening for showers and dishwashers, etc, and the water heater basically won't need to turn on at all.