The user-side energy storage investment under subsidy policy uncertainty

We develop a real options model for firms' investments in the user-side energy storage. After the investment, the firms obtain profits through the peak-valley electricity price spreads. They face a choice between making this irreversible investment and holding an option to delay the investment because of the uncertainty in the future price spreads. The government tries to encourage the firms to invest immediately by providing subsidies to this irreversible investment. The subsidy policy, however, can be activated or terminated at an uncertain time and therefore, the firms face additional policy uncertainty when making the decision. We derive the investment thresholds of the market spread that the firms use to make a decision on investing immediately or holding an option. To validate and demonstrate the model, we collect data from China's pilot project for energy storage and use it as an example. This dataset allows us to calibrate the model and numerically demonstrate the impacts of price-spread uncertainty and policy uncertainty on the firms' investment decision at different policy stages. For example, if the Chinese government unexpectedly announces a 30% subsidy and promises no subsidy in the near future, it can lower the spread threshold by 0.3950 RMB/kWh (or 39.8%), thus stimulating more immediate investments. This calibration exercise provides valuable policy measures that a government can use to incentivize an immediate investment in the user-side energy storage elsewhere.