An Unchallenged Regulatory Order Bars a Fresh Petition on the Same Tariff — Appeal No. 325 of 2026

Haryana Power Purchase Centre v. M/s Siwana Solar Power Projects Ltd. & Haryana Electricity Regulatory Commission decided on 18 September 2026 

Background

HPPC and Siwana executed a PPA in 2014 for a 5 MW solar plant. Clause 4.1 fixed the applicable tariff as the lowest of three options: the HERC (State Commission) generic tariff, the lowest tariff accepted in HPPC’s first long-term competitive bidding tender, or the lowest tariff in HAREDA’s first reverse-bidding tender. A tariff of Rs. 6.44/kWh was discovered. HERC, by order dated 20.01.2026, held Siwana bound by the PPA and directed year-to-year tariff corresponding to a levelized Rs. 6.44/kWh. That order was upheld by Appellate Tribunal for Electricity on 27.05.2019 in Appeal No. 150 of 2016.

Separately, PPAs with four other developers under the same tender were initially rejected by HERC and Appellate Tribunal by judgment dated 09.03.2018 in Appeal Nos. 278 and 307 of 2016 directed their approval at Rs. 5.68/kWh. The Hon’ble Supreme Court dismissed the developers’ appeals on 10.10.2023. HPPC thereafter paid Siwana at Rs. 5.68/kWh  and HERC by order dated 10.05.2019 permitted that rate as an interim arrangement.

Siwana’s Petition No. 26 of 2024, seeking implementation of Rs. 6.44/kWh was dismissed in limine by HERC on 12.11.2024 on the principles of res judicata. No appeal was filed against that order. Siwana then filed Petition No. 78 of 2025 and HERC by the impugned order dated 14.05.2026 granted Rs. 6.44/kWh from 1 April 2019, with differential tariff, interest at 9.15% per annum and late payment surcharge.

Findings

On res judicata. HERC’s order dated 12.11.2024 had held that the sum and substance of all of Siwana’s petitions was the grant of Rs. 6.44/kWh, that the issue had attained finality and that res judicata applied. That order went unchallenged. Comparing the prayers in Petition No. 26 of 2024 and Petition No. 78 of 2025, the Appellate Tribunal found them identical, the parties the same and the subject-matter the same. Applying Section 11 CPC and Syed Mohd. Salie Labbai v. Mohd. Hanifa, (1976) 4 SCC 780, Satyadhyan Ghosal v. Deorajin Debi, 1960 SCC OnLine SC 15, Sulochana Amma v. Narayanan Nair, (1994) 2 SCC 14, Swamy Atmananda v. Sri Ramakrishna Tapovanam, (2005) 10 SCC 51, Bhanu Kumar Jain v. Archana Kumar, (2005) 1 SCC 787 and M. Nagabhushana v. State of Karnataka, (2011) 3 SCC 408, the Appellate Tribunal held that the doctrine operates even where the earlier decision may be erroneous, the remedy lying in appeal or review and not in fresh litigation.

The “past dues versus prospective tariff” distinction drawn by HERC in the impugned order was held to be legally unsustainable. The impugned order was set aside.