Just charging your car when the demand is low is probably enough to drastically reduce the overall cost of the system. And this has basically no impact on the battery lifespan.
A trial in the UK resulted in customers earning up to £725/year [1]. With increased renewables on the grid leading to increased flutucations in the wholesale price of electricity, providing V2G/V2H will further reduce a customer's electricity bill on top of the savings offered by smart charging eg. Charge Anytime Tariff is 7p per kWh for EV charging [2] vs 27p kWh average Apr - Jun 2025 [3].
Just charging your car when the demand is low is probably enough to drastically reduce the overall cost of the system. And this has basically no impact on the battery lifespan.