Solar and wind start with a resource study. A battery starts with a merchant or contracted use: shifting energy, holding capacity, or providing a grid service. Mixing those revenues into one cell hides which assumption you are actually betting on.

Name the revenue, then the contract

Capacity payments, energy arbitrage, and ancillary services do not fail the same way. A capacity contract can be dull and financeable. Arbitrage depends on a spread that the model often freezes. Ask which dollars are contracted, for how long, and which dollars are a view on volatility.

Degradation is the production estimate

Every cycle spends life. Augmentation capex is not optional color. It is how the project keeps the duration it sold. If the model holds revenue flat while the battery fades, the out years are fiction.

Underwrite the job the battery is paid to do. Then ask what is left when that contract ends and the cells are older.