This paper provides a practical framework to help regulators and policymakers understand how renewable energy (RE) mandates affect utility finances and electricity tariffs under cost-of-service regulation. Rather than forecasting specific country outcomes, it isolates the structural cost drivers that determine whether adding renewables raises or lowers the annual revenue requirement relative to a 0% RE case. Moderate RE targets can reduce costs when fuel prices are high, but the same targets may increase the ARR when fuel is inexpensive or WACC is elevated. The study also demonstrates that ownership structure matters: IPP-based models often accommodate higher RE shares, while utility ownership places earlier pressure on the regulated asset base. By situating these effects across different country conditions, the paper provides regulators with a structural basis for assessing how ambitious RE targets may influence revenues.
