The central standard makes co-located storage compulsory. At least one State gives that same asset a deviation band of Nil.
On 3 September 2026 the Central Electricity Authority published for comment the draft (Technical Standards for Construction of Electric Plants and Electric Lines) 2nd Amendment, Regulations, 2026 — F. No. CEA-TH-17/1/2021-TETD Division, under section 177 of the Electricity Act, 2003. The proposed Regulation 106B(20) would require ground-mounted solar and on-shore wind plants commissioned after 1 July 2027 to carry a co-located energy storage system of at least two hours' duration and ten per cent of installed capacity, rising to four hours for plants commissioned after 1 July 2029 and up to 30 June 2031.
I filed objections and suggestions on 16 September 2026. They are reproduced below in full, and the filed document is linked at the foot of this page. I have no commercial interest in any generator, developer, supplier, licensee or financier, and take no fee, commission or consideration from any party in this field.
Karnataka has notified the Forecasting, Scheduling, Deviation Settlement Mechanism and related matters for Sellers of Wind, Solar and WS-Hybrid Generation sources Regulations, 2026 — Notification No. KERC/WS(DSM)/2026-27/2150 dated 19 June 2026, published in the Karnataka Gazette of 22 June 2026. Clause 13(e) sets the permissible deviation:
| Generator / seller | Deviation range |
|---|---|
| Wind generators / sellers | ± 10% (within >90% and <110%) |
| Solar generators / sellers | ± 5% (within >95% and <105%) |
| Hybrid generators / sellers | ± 10% (within >90% and <110%) |
| ESS (with wind or solar or WS-hybrid) | Nil |
The asset the Authority proposes to make compulsory is, in that State, the only class of asset with no tolerance band at all. A wind plant may deviate by ten per cent without charge and a solar plant by five; a storage system attached to either has none.
By clause 4 of the same regulations, they reach sellers supplying the distribution licensees, third parties under open access, and captive users alike — wind at 10 MW and above, solar and hybrid at 5 MW and above. Clause 4 also provides that the battery capacity shall not exceed the MW connectivity granted at the interface point: a limit in MW, where the Authority's requirement is in hours of storage at a percentage of capacity. The two instruments measure the same asset on different axes.
The draft does not say at what point energy discharged from the mandated storage is deemed generated for scheduling, metering and accounting — at the hour of discharge, or at the hour of charging. Where banked energy is settled slot by slot, that single question decides what the energy is worth. Clause 12.e(ii) of the Karnataka (Terms and Conditions for Open Access) Regulations, 2025 provides:
The energy banked during TOD Slot-1 & Slot-3 … shall be permitted to be drawn during TOD Slot-1, Slot-2, Slot-3 and Slot-4. The energy banked during TOD Slot-2 & Slot-4 shall be permitted to be drawn during TOD Slot-2 & Slot-4 only.
On the slot periods in the illustration at clause 12.e(iv) — Slot-1 is 6 am to 9 am, Slot-2 is 9 am to 6 pm, Slot-3 is 6 pm to 10 pm, Slot-4 is 10 pm to 6 am — energy banked in the solar hours cannot be drawn in the evening peak at all, and the regulations contain no provision permitting it on payment of any additional charge. Whether a co-located battery alters that turns entirely on the deemed hour of generation, and no instrument I have read answers it.
The second proviso bounds the four-hour requirement at 30 June 2031. The first proviso, requiring two hours, carries no end date. Read together, a plant commissioned on 1 July 2031 appears to fall back to two hours, having been preceded by plants required to carry four. A developer taking a financing decision in 2027 for a plant commissioning in 2031 or later cannot size the asset on the draft as it stands.
Three pages. Sent by email to the Chief Engineer (Legal), Legal Division, Central Electricity Authority, on 16 September 2026.
Three pages. Sent to the same address on 22 September 2026, adding evidence from Tamil Nadu and one point on Karnataka.
Three pages, including an annex of the instruments cited. Dated 25 September 2026 and sent to the same address on 26 September 2026, on the metering of co-located storage.
The Karnataka regulations cited above were read from the notified texts. The wider position — banking charges, drawal restrictions, quantum caps and expiry across Karnataka, Gujarat and Andhra Pradesh — is set out with its sources in Report No. 2, the India Renewable Banking Index, published 13 September 2026. Free, and open to correction.
If you think any statement on this page is wrong, write — research@dsnikam.in. Corrections are published with attribution.