I've got a 5kW array of panels so yea, piddly stuff like charging USB is nothing - it's more the principal of the thing.
My EV charger is definitely the biggie. The system will dynamically adjust charging current in 1A steps to make use of available excess generation. It works pretty well - 16kWh spinning my meter backwards would earn me a whole $1.50 - instead it added ~20% charge to the car.
Huh, I thought it was just me that did that - I just assumed everyone else was so much more disciplined than me...