I can't imagine a scenario where you've got a large enough solar system that you'd want to be running a dishwasher off it, and you don't already have some battery storage elsewhere in that system.
The money efficiency isn't great - if you had control of the design of the dishwasher, simply having a hot block of concrete inside that you heated when there was spare energy would work out far cheaper.
Concrete costs far fewer $$$'s than batteries do, per kwh of heat stored, it also doesn't require inverters, balancing or safety systems, ad lasts millions of cycles rather than thousands.
