During the past 10 years of working on V2G, the question posed to me the most, invariably always centers on battery degradation.
The good news: it is low
We now have a much better understanding from simulations, laboratory tests and actual V2G commercial deployments.
Nuvve/Nissan/Enel have deployed 10 Nissan e-NV200 EVs (24 kWh), 10 Enel V2G chargers (10 kW) and a Nuvve aggregator at a utility customer site in Denmark. The deployment was started Sep. 6, 2016 and has been in successful operation for more than 4 years logging 250,000+ hours V2G operation (10 EVs) delivering Frequency Regulation (regulation every second) to the Danish TSO – 118 hours per week (heavy energy flow).
The EV batteries have been analyzed by the independent Danish Technical University and run through battery models by Nissan Corporate Research and the results published in the ACES project.
Summary: After 5 years 7%-12% battery degradation incl V2G of 1%-2%. Main degradation is from aging, driving and fast charging (figure).
An analysis from Honda and Prof. Willett Kempton, University of Delaware comes to similar low degradation from V2G.
Nissan feels so confident that it warrants its batteries for V2G use (use must be pre-approved by Nissan).