By the end of 2025 storage in Chile had doubled its presence in the national electricity market, reaching 3.2 GW of installed capacity and 9.1 GWh of storable energy; in April 2026 the pipeline closed with a portfolio of more than 10 GW of BESS projects in active deployment, close to 44 GWh. The expansion concentrated on short-duration batteries —on the order of 4 to 6 hours— located where solar penetration is high and transmission is congested.
The document settles a concrete question: how stored energy should be valued while the new dispatch architecture is still being implemented. Today BESS operation rests on the incurred charging cost. If a battery charged at zero marginal cost during an hour of curtailment, that energy carries a zero variable cost into real-time operation, and discharging it at night artificially depresses marginal costs. The incurred cost measures what it took to acquire the stored energy; the opportunity cost measures what is given up by using it now rather than later. For a dispatchable resource, it is the latter that guides efficient operation.
The gap shows up on three planes
- Short-term and intraday scheduling: valuing only by charging cost can induce premature discharges or allocate energy that would be more valuable in later, more demanding hours.
- Real-time operation: early discharges, manual instructions and relevant deviations from the program are observed without sufficient traceability to assess whether they were efficient.
- Price formation: the disconnect between program, actual dispatch and intertemporal valuation delivers incomplete signals both for operation and for investment in flexibility.
The enabling framework already exists
Chile is not starting from scratch. Opportunity cost has been applied to reservoir water for decades, and in 2025 reservoir plants set the price close to 40% of night hours. The Coordinator already uses it for plants with regulation capacity and relevant impact on operation, and applied a cost-minimization logic with intertemporal signals to the BESS El Salvador case. The amendments to DS125/2017 require computing opportunity cost and automating dispatch, but their implementation may take two to three years. Simulations of the Chilean system for 2027 run in AMEBA show that from 1 GW of installed capacity onward BESS already produce relevant effects on the system's marginal costs and operating costs.
Four priority measures
- Adopt an explicit intertemporal valuation methodology based on opportunity cost as the general rule, possibly excluding units operating under self-dispatch.
- Add intraday rescheduling triggers tied to early discharges, state-of-charge variations and significant differences between program and actual operation.
- Strengthen real-time traceability: systematic records of instructions, operational justifications and expected effects on security, congestion or marginal cost.
- Align modeling, dispatch and pricing, incorporating real operating constraints, greater temporal granularity in critical hours and public criteria for breaking ties among degenerate solutions.