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Indian power generators face a structural DISCOM settlement reconciliation gap — state DISCOMs pay on 90 to 180 day cycles under PPAs that split tariff into fixed capacity and variable energy components (or a single levelised renewable tariff), SLDC energy accounting in 15-minute blocks creates DSM exposure on scheduled-vs-actual deviation, REC inventory accumulates monthly with trade settlement on IEX or PXIL day-specified sessions, and the Late Payment Surcharge Rules 2022 entitle a base MCLR-plus-2 percent recovery escalating 0.5 percent per month capped at MCLR plus 5 percent — each rail has its own data source and an audit-readable close needs all four reconciled to the generator's revenue ledger.
Tie each monthly DISCOM invoice to the SLDC energy accounting statement (scheduled MUs in 15-minute blocks) and to the SCADA-recorded actual generation, decompose tariff into fixed capacity and variable energy under PPA terms with deemed generation events flagged separately, compute the DSM charge or credit per 15-minute block on the regional slab against the day-ahead forecast, age each invoice from due date and apply the LPS Rules 2022 slab progression for the LPS receivable booking, tie REC issuance in the registry to generation MUs and tie REC sales on IEX or PXIL sessions to trade proceeds net of exchange fee and TCS reaching the generator bank account, and keep the GST exemption on electricity sale (Notification 2/2017 entry 104) separate from any taxable ancillary service component under SAC 998633.
PPA master per DISCOM offtake with tariff structure (fixed plus variable or levelised), deemed-generation clauses, billing cycle and dispute resolution clause, SLDC energy accounting ingest by 15-minute block with scheduled and actual MWh per period, DSM rate table by regional slab and frequency band updated per CERC notification, REC registry account with issuance pending and issued status, IEX and PXIL trade settlement ingest with exchange fee and TCS line items, LPS ageing buckets keyed to PPA due date with MCLR-plus-X slab progression, PRAAPTI portal monthly outstanding ingest for cross-check, and GST line-treatment table separating exempt electricity sale from taxable ancillary services.
A monthly reconciled view per DISCOM showing invoice raised vs SLDC energy accounting vs SCADA actual generation with deviation flagged, DSM charge or credit by 15-minute block aggregated to the period, REC inventory with issued-pending-sold status reconciled to generation MUs and to IEX or PXIL trade proceeds tied to bank credit, an LPS receivable schedule aged by invoice with the slab-progression LPS rate applied and the receivable separated from principal, and a GST classification view splitting exempt electricity sale from any taxable ancillary line for GSTR-3B 3.1(c) versus 4(A)(5) routing.
A 50 MW solar IPP in Karnataka closes its books for May 2026 and tallies its DISCOM receivable position. Monthly energy supplied: 9.6 million units (MUs) at a levelised PPA tariff of ₹2.88 per kWh, gross invoice value ₹27.65 crore. Cash actually received against the May invoice: zero — the DISCOM’s last realised payment cleared the December 2025 bill, leaving five months of invoices ageing ₹138 crore in principal alone, with LPS receivable computed under the Electricity (Late Payment Surcharge and Related Matters) Rules 2022 adding a further ₹6.4 crore. Anyone running DISCOM settlement reconciliation India at scale recognises the pattern. The PPA looks bilateral on paper. The settlement is a four-rail reconciliation against a regulated payment counterparty whose default risk is structural.
Quick reference
| Item | Value |
|---|---|
| Governing framework | Electricity Act 2003 · CERC and SERC regulations · PPA between generator and DISCOM |
| Typical DISCOM payment cycle | 30 to 45 day billing due date · realised cycle commonly 90 to 180 days |
| Tariff structure (thermal IPP) | Two-part — fixed capacity charge plus variable energy charge |
| Tariff structure (solar / wind IPP) | Single levelised tariff per kWh, often with a deemed-generation clause |
| Scheduling and energy accounting | SLDC under POSOCO regional control · 15-minute time-block granularity |
| Deviation Settlement Mechanism | CERC-notified slab linked to grid frequency and reference rate |
| REC issuance | Central Agency registry · one REC per MWh of CERC-accredited generation |
| REC trading venues | IEX and PXIL day-specified sessions, typically last Wednesday of each month |
| LPS framework | LPS Rules 2022 — base SBI MCLR plus 2 percent, escalating 0.5 percent per month, capped MCLR plus 5 percent |
| GST on sale of electricity | Exempt — Notification 2/2017-Central Tax (Rate), entry 104, HSN 27160000 |
| GST on ancillary service line | Taxable at 18 percent under SAC 998633 where billed separately |
| TDS on PPA payments | Sale of electricity treated as sale of goods — generally outside Section 393 services-TDS framework |
| PRAAPTI portal | Monthly outstanding disclosure mandated under LPS Rules 2022 |
How does the DISCOM settlement architecture work?
A power generator under a PPA with a state DISCOM (Karnataka’s BESCOM, Maharashtra’s MSEDCL, Tamil Nadu’s TANGEDCO, and so on) raises a monthly invoice on the offtaker computed from three artefacts. First, the SLDC energy accounting statement — the regional or state load despatch centre, operating under the Grid Controller of India (POSOCO) framework, publishes a monthly statement of scheduled energy in 15-minute time blocks against the day-ahead and intra-day revised schedules, alongside actual injected energy at the metering point at the periphery of the generating station. Second, the PPA-contracted tariff — either a two-part fixed-plus-variable structure for thermal capacity or a single levelised tariff for solar and wind. Third, any deemed-generation entitlement triggered by grid backdown, force majeure, or planned outage of the transmission corridor for which the PPA holds the DISCOM responsible.
The invoice flows to the DISCOM with a contractual due date typically 30 to 45 days from invoice. In practice, realisation is 90 to 180 days for most state DISCOMs — and longer for the structurally distressed ones. The gap between due date and realisation is the principal-and-LPS reconciliation problem. The Late Payment Surcharge Rules 2022 framed under Section 176 of the Electricity Act 2003 specify a uniform LPS framework so the LPS becomes a contractually enforceable recovery line, not a negotiation.
What are the four reconciliation rails?
Rail 1 — PPA tariff and SLDC energy accounting
The PPA’s tariff structure determines what the invoice is composed of. A thermal IPP with a two-part tariff bills two distinct lines — fixed capacity charge per MW of contracted capacity (compensating debt service and fixed O&M, payable regardless of dispatch subject to availability), and variable energy charge per kWh of scheduled energy linked to the prevailing fuel cost. A solar or wind IPP under a levelised tariff bills a single rate per kWh of scheduled energy, with no fixed-variable split.
The SLDC energy accounting statement is the source of truth for scheduled energy. The generator’s reconciliation must tie each invoice line to the SLDC statement at the 15-minute block level — and to the SCADA recording at the generator’s own metering point. A gap between SLDC scheduled energy and the SCADA actual injection is a metering or telemetry exception that needs to be raised with the load despatch centre under the energy accounting dispute resolution. Deemed-generation events — for example a transmission corridor outage during peak solar hours that prevents evacuation — are flagged separately on the invoice with the SLDC’s corroborating event log.
See DISCOM tariff true-up reconciliation under MERC/KERC for the periodic SERC-driven tariff revision process that feeds back into the levelised rate over the PPA tenor.
Rail 2 — Deviation Settlement Mechanism (DSM)
The Deviation Settlement Mechanism, notified by CERC and operated through regional load despatch centres under POSOCO, charges generators and buyers for the gap between scheduled energy and actual injected energy in each 15-minute block. For thermal generators, deviation outside a permitted band attracts a slab-based charge linked to the grid frequency at the time of the block — under-injection during a low-frequency event is penalised more heavily, and over-injection during a high-frequency event likewise.
For renewable generators under forecast-and-schedule obligations (mandated in most states since 2019), the DSM regime is differentiated. The generator submits a day-ahead forecast for each 15-minute block, the SLDC revises in intra-day windows, and deviations are charged on a separate renewable-DSM slab structure. A solar IPP that overstates a cloudy-afternoon forecast and under-injects by 20 percent on a particular block can see DSM charges of ₹0.25 to ₹0.75 per kWh on the off-the-mark block, depending on the regional slab and the prevailing reference rate.
Reconciliation ties each block’s deviation to the DSM slab, computes the DSM charge or credit, and either nets it against the monthly invoice or books it as a separate ancillary service line — depending on the regional billing convention.
Rail 3 — REC inventory and IEX or PXIL trade settlement
A renewable generator that elects the REC mechanism instead of a preferential tariff accumulates Renewable Energy Certificates issued by the Central Agency at one REC per MWh of CERC-accredited generation. The issuance is lag-adjusted to the verification cycle — typically monthly, with the generation month’s RECs issued mid-way through the following month.
RECs are traded on the day-specified power exchange sessions on IEX and PXIL, typically the last Wednesday of each month. The settlement file for each session shows RECs sold, weighted-average clearing price (the floor and forbearance price band is set by CERC), exchange fee deducted at the prescribed rate per REC, TCS where applicable, and the net credit reaching the generator’s bank account on T plus two.
The reconciliation ties generation MUs in the SLDC statement to RECs issued in the registry, RECs issued to RECs sold per session, and trade proceeds net of exchange fee and TCS to the bank statement credit. RECs that remain unsold at the end of a session roll into the next session’s inventory, subject to validity tenor under CERC’s REC framework.
See IEX and PXIL power exchange reconciliation for Indian open-access buyers for the buyer-side mirror reconciliation where an open-access consumer ties RPO-obligation purchases to RECs received in the registry account.
Rail 4 — Late Payment Surcharge and PRAAPTI cross-check
The Electricity (Late Payment Surcharge and Related Matters) Rules 2022, notified by the Ministry of Power under Section 176 of the Electricity Act 2003, fixed a uniform LPS framework that replaced the heterogeneous PPA-by-PPA late payment clauses of earlier eras. The base LPS rate is the prevailing one-year SBI MCLR plus 2 percent on the first month of continued default after the bill due date. For each successive month of default, the rate escalates by 0.5 percent. The total LPS rate is capped at SBI one-year MCLR plus 5 percent.
The Rules also impose monthly outstanding disclosure on the PRAAPTI portal — the Ministry of Power’s online dashboard for DISCOM dues to generators — and provide for graded supply-curtailment triggers where dues remain unpaid through prescribed instalments. For the generator’s reconciliation, every DISCOM invoice is aged in monthly buckets from the PPA-specified due date, the applicable LPS slab is computed for each ageing bucket, and the LPS receivable is booked as a distinct line item separate from principal receivable.
The PRAAPTI portal cross-check is operationally important — the generator’s internally-tracked DISCOM outstanding should reconcile to what the DISCOM itself discloses on PRAAPTI each month. Persistent mismatches between internal ageing and PRAAPTI disclosure surface invoice acceptance disputes that need resolution under the PPA’s dispute clause before the LPS recovery can be enforced.
Worked example — 50 MW solar IPP, May 2026
A 50 MW solar IPP in Karnataka under a 25-year PPA with BESCOM at a levelised tariff of ₹2.88 per kWh.
May 2026 numbers:
- Scheduled energy (SLDC monthly statement, aggregated from 15-minute blocks): 9.62 million units (MUs).
- SCADA actual generation at the periphery meter: 9.60 MUs (0.2 percent loss within tolerance — no metering exception).
- DSM charges for forecast deviations across the month: 18 blocks flagged with under-injection of 8 to 22 percent (cloud cover), aggregate DSM charge ₹14.4 lakh net of one block of over-injection credit.
- Gross monthly invoice on BESCOM: 9.60 MUs × ₹2.88 = ₹27.65 crore, less DSM net charge ₹14.4 lakh = ₹27.50 crore net invoice.
DISCOM payment position at end-May:
- May invoice ₹27.50 crore — due date 30 June, currently within billing window, no LPS.
- April invoice ₹26.4 crore — overdue 1 month, LPS at MCLR plus 2 percent on outstanding.
- March, February, January, December invoices — overdue 2, 3, 4, 5 months respectively, LPS slabs escalating 0.5 percent per month per slab progression.
- Principal receivable: ₹138 crore (5 unpaid months at slightly varying monthly invoices).
- LPS receivable: ₹6.4 crore, computed on the slab progression — booked separately from principal.
Assume SBI one-year MCLR at 8.85 percent. April’s overdue invoice LPS at MCLR+2% = 10.85 percent annualised on one-month outstanding = approximately ₹23.9 lakh. March’s LPS at MCLR+2.5% on two-month outstanding ≈ ₹61.6 lakh. February’s at MCLR+3% on three-month outstanding ≈ ₹1.05 crore. And so on through the December invoice at MCLR+4% on five-month outstanding ≈ ₹2.16 crore. Total LPS booking on the month: ₹6.4 crore receivable.
PRAAPTI cross-check: BESCOM’s monthly disclosure on the PRAAPTI portal at end-May shows ₹141 crore outstanding to this generator — a ₹3 crore reconciliation gap. Investigation reveals two disputed invoice line items where BESCOM has not accepted the deemed-generation charges raised by the generator for a March transmission outage; the disputed line is being escalated under the PPA’s dispute clause. The principal-LPS recovery ledger continues on the accepted invoice value until the dispute is resolved.
REC position (where applicable for an open-access component of the same plant) and IEX trade settlements would track on Rail 3 in parallel.
Quantify the cost of unresolved DISCOM invoice exceptions
For power generators where every unaccepted invoice line on PRAAPTI represents a frozen LPS recovery and locked working capital, the three-way match exception cost calculator quantifies the rupee value of the lock and the chase hours required to clear it.
Open the Three-Way Match Exception Cost Calculator →What are the operational controls that close the gap?
The power generator who runs a clean DISCOM settlement reconciliation does six things:
- Daily SLDC ingestion and 15-minute block tie to SCADA — the energy accounting statement is published monthly but the underlying block-level data is available daily through the SLDC interface. Ingest daily so metering or telemetry exceptions surface within 24 hours, not at month-end.
- PPA master under change control — tariff escalation indices, deemed-generation triggers, billing addresses, due-date convention. A stale PPA master is the most common source of invoice mis-billing.
- DSM slab table refreshed per CERC notification — frequency-linked slabs and the renewable forecast-and-schedule slab structure are revised periodically; an out-of-date table books wrong DSM expense.
- LPS ageing buckets keyed to PPA due date — not invoice date and not bill receipt date — with monthly slab progression applied per the LPS Rules 2022.
- PRAAPTI portal monthly reconciliation — internal outstanding vs DISCOM’s disclosed outstanding, with disputed line items tracked to PPA dispute-resolution timelines.
- REC registry tie to generation — RECs issued vs RECs sold per IEX/PXIL session vs bank credit on T plus two, with unsold inventory rolled and validity tracked.
These are operational controls, not technology controls. The reconciliation layer makes them auditable and chase-able. Without the layer, LPS receivable goes unbooked, deemed-generation disputes get lost in the queue, and DSM exposure compounds.
How does DISCOM reconciliation interact with the broader power sector tax and regulatory stack?
A power generator does not run the DISCOM offtake rail in isolation. The same generator carries:
- Transmission charges from the central and state transmission utility — see transmission charges reconciliation: CTU/STU/PGCIL billing for the periodicity, the regional pool sharing, and the long-term access vs medium-term open access components.
- GST exemption on electricity sale under Notification 2/2017 entry 104, with taxable ancillary lines under SAC 998633 where billed separately — the reconciliation layer must hold the split at invoice level.
- Open-access trade exposure where the generator sells a portion of its capacity on IEX or PXIL day-ahead or term-ahead markets — see IEX and PXIL power exchange reconciliation for Indian open-access buyers for the buyer-side mirror.
- SERC tariff true-up cycles — see DISCOM tariff true-up reconciliation under MERC/KERC for the periodic regulatory revision process.
The DISCOM settlement reconciliation is one rail in a five-rail stack — DISCOM offtake, DSM, REC trading, transmission charges, and SERC true-up. A clean rail-by-rail close is what auditors look for in a CARO 2020 internal financial controls walk-through for a power generation business. See bank reconciliation in India for the foundational bank-side discipline that ties all rails to the audit trail.