CERC’s storage tariff makes the value of a charged battery visible

A battery can be installed at a power station and still be unable to deliver electricity when the grid needs it. The Central Electricity Regulatory Commission’s second tariff amendment, published in April, supplies a framework for specified integrated storage at generation and interstate transmission facilities whose tariffs fall under the commission’s jurisdiction. The economic test is whether payment reflects the ability to discharge in valuable hours and accounts for the electricity required to charge. The investment is worthwhile where the resulting service costs less than a credible alternative. CERC tariff second amendment, Gazette 257 of 2026 · CERC, draft tariff regulations amendment

A power rating is one part of the product

The amendment addresses integrated storage that uses a common connection with eligible generating stations or transmission systems. It defines measures including declared capacity, the battery’s ability to discharge and relevant energy consumption. The scope matters. Its arrangements address regulated projects within the stated framework. A standalone merchant project with a different contract and revenue sources can have a different incentive to charge or discharge. CERC tariff second amendment, Gazette 257 of 2026

A 100 MW device can deliver 100 MW at an instant under its rated conditions. A 200 MWh usable energy budget can sustain that rate for two hours when fully charged. During a four-hour shortage, another device with the same power rating and twice the energy can provide a different service. A device already used in an earlier hour has less remaining energy unless it can recharge. For the buyer, capacity means an amount available at a specified time for a specified duration.

Charging carries a price

Suppose a battery delivers 200 MWh at a time when the avoided cost of energy is ₹8 per kWh. At an assumed round-trip efficiency of 80%, it requires 250 MWh of charging energy. If that energy costs ₹3 per kWh, it costs ₹7.5 lakh and the discharged energy has an illustrative gross value of ₹16 lakh. The energy spread is ₹8.5 lakh before fixed costs, degradation, charging constraints and any reserve value. If the charging price rises to ₹6.50 per kWh, the input cost becomes ₹16.25 lakh. The energy spread alone becomes slightly negative. A separate reliability value could still justify keeping the battery charged.

Who decides to charge and who pays are important questions. A service provider paid for availability has a reason to preserve charge for contracted hours. If someone else pays the energy cost, the provider’s charging choices need rules or incentives that discourage unnecessary expense. When the dispatch centre can call the device for grid support, accounting has to show who received the benefit and when a call displaced another promised service.

Compare the service with the next-best asset

The strongest argument for a predictable tariff is that an integrated device can provide benefits that are difficult to sell separately. It may defer an upgrade, help a generating station vary its output or provide a service to the wider network. Stable compensation can finance an investment that a volatile short-term price would undersupply. The danger is paying for capital and assuming the operating benefit. Record usable energy at the required times, actual dispatch, charging input and degradation, and compare performance with the alternative the project was intended to replace.

In a location with repeated short-duration constraints, measured availability and reliable discharge might justify additional storage. Where constrained periods last longer than the asset can serve, a grid upgrade, longer-duration resource or demand response could have more value. The relevant comparison includes the full life of each option and its effect on expected scarcity, including the value of services that can be provided at the same time without double counting.

Battery life makes the comparison dynamic. Calling an asset more often can earn additional revenue while advancing the date at which usable capacity falls below the contract requirement. Reporting both delivered energy and retained capability makes it easier to compare a heavily used project with one kept mostly in reserve.

A regulated tariff can make integrated storage financeable. Its economic value is the availability of usable electricity in the hours a purchaser would otherwise have to cover at greater cost.