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How-To · 11 min read

Transmission Charges Reconciliation: CTU/STU/PGCIL Billing for Open-Access Customers

An open-access industrial consumer drawing power from an inter-state IEX trade pays a stack of transmission charges that almost no purchasing manager fully ties out: CTU PoC charges allocated by withdrawal node, STU wheeling, transmission losses in kind, reactive energy charges, banking charges on surplus carried forward, cross-subsidy surcharge under Section 42, and an additional surcharge for stranded DISCOM capacity. The PGCIL bill and the State Transco bill arrive on different cycles, in different formats, and a 10 MW consumer routinely sees a 4-7% variance between expected and billed transmission cost.

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Published 12 June 2026
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Knowledge Card
Problem

Indian open-access industrial consumers face a structural transmission reconciliation gap — PGCIL bills inter-state PoC charges quarterly with node-wise rates under the CERC Sharing Regulations 2020, the State Transco bills intra-state transmission monthly under a separate SERC tariff order, the DISCOM bills wheeling and cross-subsidy surcharge and additional surcharge on a third cycle, banking charges accrue in kind on injection-drawal mismatches, and transmission losses are settled in energy via the POSOCO Regional Energy Account. A 10 MW consumer routinely sees 4-7% variance between expected and billed transmission stack with no single ledger that ties the rails together.

How It's Resolved

Build a withdrawal-node and injection-node master with the applicable PoC rate per quarter, schedule drawal against trader confirmation and IEX/PXIL trade ID, apply the regional loss factor to derive required injection, reconcile PGCIL inter-state bill (PoC + loss + reactive) against schedule, reconcile STU bill (transmission charge per ₹/kW/month or ₹/kVAh) against connected load and energy drawn, reconcile DISCOM bill (wheeling + CSS + AS) under the current SERC tariff order with effective-date control, track banked injection against drawal claims with banking charge in kind, and tie the Regional Energy Account back to the trader's settlement confirmation.

Configuration

Connection-point master with withdrawal node code, sanctioned load, voltage level, host DISCOM and host state, PoC rate table by quarter and node (long-term ₹/MW/month, short-term ₹/MWh), regional loss factor table per POSOCO region, STU transmission tariff order with effective date and ₹/kW/month rate by voltage, DISCOM wheeling tariff with CSS and AS components by consumer category, banking regulation with charge percentage and time-window restrictions per state, trader/IEX/PXIL trade register with schedule ID, REA ingest per settlement period, and SERC tariff order register with effective-from and effective-to dates.

Output

A monthly reconciled view per connection point showing scheduled drawal vs REA actual vs trader confirmation, PGCIL bill ties under PoC rate × schedule + loss component, STU bill tie against tariff order × connected load and drawal, DISCOM bill tie showing wheeling + CSS + AS split with each rate validated against the current SERC order, banking ledger showing injected-banked-withdrawn-expired energy in kWh and the in-kind banking charge retained by DISCOM, and a transmission-stack variance bridge from expected to billed with each delta coded by reason — node reclassification, tariff revision, schedule deviation, loss-factor change, or banking expiry.

A 10 MW open-access industrial consumer in Pune, drawing power from an inter-state IEX trade originating in Chhattisgarh, closes its books for May 2026 and opens four bills: a PGCIL inter-state transmission bill for ₹38.4 lakh, an MSETCL intra-state transmission bill for ₹14.6 lakh, an MSEDCL wheeling-plus-CSS-plus-AS bill for ₹62.3 lakh, and a DSM (Deviation Settlement Mechanism) bill of ₹2.1 lakh net. Against the procurement team’s expected stack of ₹109.8 lakh, the four bills sum to ₹117.4 lakh — a 6.9% variance. Anyone running transmission charges reconciliation India at scale knows the pattern. The PoC framework looks elegant in the regulation. The reconciliation hides in the joins between four cycles, three regulators, and a Regional Energy Account that publishes settlement-period by settlement-period.

Quick reference

ItemValue
Inter-state transmission billingCERC Sharing Regulations 2020 (and amendments) — PoC framework
Central Transmission UtilityPGCIL (deemed CTU under Section 38, Electricity Act 2003)
Intra-state transmission billingState Transco (MSETCL, TANTRANSCO, KPTCL, GETCO, etc.) under SERC tariff orders
Wheeling, CSS, ASDISCOM-billed under Section 42, Electricity Act 2003 — SERC tariff order
PoC rate periodicityQuarterly, node-wise — published by CTU
Loss settlementIn kind (kWh) — POSOCO Regional Energy Account
Banking chargesState-defined percentage retained in kind, time-window restricted
Deviation settlementDSM bill under CERC DSM Regulations — 15-minute settlement blocks
Typical transmission-stack variance band4% to 7% of expected billed cost

How does the inter-state PoC architecture work?

The CTU (PGCIL) pools the Yearly Transmission Charges of all ISTS licensees and allocates them to withdrawal and injection nodes through the Point of Connection framework. Each node has a published PoC rate that varies by quarter — long-term and medium-term open access pay a ₹/MW/month charge on contracted capacity, short-term open access pays a ₹/MWh charge on scheduled drawal. Losses are billed in energy: a withdrawal in the Western Region against an injection in the Eastern Region applies the inter-regional loss factor, and the consumer (or its trader) arranges additional injection at the source to cover that loss.

POSOCO’s Regional Load Despatch Centres run the system operation. At the end of each settlement period (15 minutes under the current CERC framework), the Regional Energy Account is computed: entity-wise scheduled drawal, actual drawal at the metering boundary, deviation in MW and frequency band, and apportionment of inter-regional and intra-regional losses. The REA is the authoritative settlement record. The PGCIL bill is its rupee expression at the published PoC rate; the DSM bill is its rupee expression of deviation at the frequency-band rate.

What are the four reconciliation rails?

Rail 1 — Schedule vs trader confirmation vs IEX/PXIL trade record

The 15-minute schedule the consumer files with its trader has to match the trader’s confirmation to the RLDC and the trade record at the exchange. A common error is the trader’s confirmation being booked against a slightly different node code or a different injection source than the trade record — the schedule executes but the PoC rate applied at billing is for the wrong node. Reconciliation must tie schedule ID, trade ID, withdrawal node, injection node, and settlement-period block one-for-one before any downstream bill arrives. See IEX and PXIL power exchange reconciliation for Indian open-access buyers for the trade-side detail.

Rail 2 — PGCIL inter-state bill — PoC + loss + reactive

PGCIL’s monthly bill carries three principal lines. The PoC charge is rate × scheduled drawal (or contracted capacity for long-term). The loss line is the inter-regional and intra-regional loss in kWh, settled at the rate the regulation specifies for energy compensation. The reactive energy charge applies where the consumer’s monthly weighted power factor falls outside the regulatory band — typically below 0.95 leading or above 0.97 lagging. Reconciliation ties each line to the schedule and to the published rate notification. The most common variance is a quarterly rate revision applied mid-month without the procurement team’s rate table being refreshed.

Rail 3 — STU and DISCOM bills under the SERC tariff order

The State Transco bills transmission charges per the current SERC order — typically ₹/kW/month on connected load at the consumer’s voltage level. The DISCOM bills three additional components: wheeling charges (use of distribution network at the consumer’s voltage), cross-subsidy surcharge (Section 42 compensation for lost cross-subsidy), and additional surcharge (Section 42 compensation for stranded DISCOM capacity). Each component is in the current State Commission tariff order, each has an effective-from date, and several states publish mid-year true-up orders that revise CSS or AS retroactively. The reconciliation must hold the tariff order on file with effective-date control and reapply prior months when a true-up order lands.

Rail 4 — Banking ledger and Regional Energy Account

Where the consumer is a captive generator or has a renewable injection contract, banking enters the picture. The state regulation defines what percentage of injected energy can be banked, the time window within which banked energy can be drawn back (commonly the same month or the same tariff slot), the banking charge retained in kind by the DISCOM (commonly 2% to 8%), and the disposal of unbanked surplus (lapse or settlement at APPC). The reconciliation maintains an injection-banked-withdrawn-expired ledger per consumer per slot and ties the monthly position to the Regional Energy Account and the state utility’s banking statement.

See DISCOM settlement reconciliation for power generators in India for the generator-side mirror of this rail.

Worked example — 10 MW Pune consumer, May 2026

A 10 MW industrial consumer in Pune drawing 7,200 MWh in May 2026 from an inter-state IEX trade with injection at a Chhattisgarh node:

Expected stack (procurement-team build-up):

  • PGCIL PoC charge: 10 MW × ₹38,000/MW/month (illustrative Western Region withdrawal node rate) = ₹38.0 lakh
  • Inter-regional loss component: 5% on 7,200 MWh = 360 MWh additional injection, valued at ₹3.6/kWh procurement cost = ₹12.96 lakh (covered upstream in energy cost, not in PGCIL line — but tracked here)
  • Reactive energy charge: expected zero on a PF-corrected plant
  • MSETCL intra-state transmission: 10 MW × ₹14,500/kW/month (illustrative) on connected load = ₹14.5 lakh
  • MSEDCL wheeling: ₹0.85/kWh × 7,200 MWh = ₹61.2 lakh
  • MSEDCL CSS: ₹0.95/kWh × 7,200 MWh = (separately within wheeling envelope) included above
  • MSEDCL AS: ₹0.10/kWh × 7,200 MWh = (separately within wheeling envelope) included above
  • DSM: expected zero on a tight schedule
  • Total expected stack: ₹109.8 lakh (transmission + wheeling + CSS + AS — energy cost separately ₹2.59 crore at ₹3.6/kWh)

Actual bills received:

  • PGCIL bill: ₹38.4 lakh — ₹0.4 lakh higher due to a node rate revision in the third quarter notification applied mid-period
  • MSETCL bill: ₹14.6 lakh — ₹0.1 lakh higher on a minor connected-load reclassification
  • MSEDCL wheeling + CSS + AS: ₹62.3 lakh — ₹1.1 lakh higher because the State Commission true-up order revised AS upward retroactively from 1 April 2026 (₹0.15/kWh against ₹0.10/kWh in the prior order)
  • DSM bill: ₹2.1 lakh net — driven by under-injection during three settlement periods on 14 May when the source plant tripped

Variance bridge:

  • PoC rate revision: +₹0.4 lakh
  • Connected-load reclassification: +₹0.1 lakh
  • AS true-up retroactive: +₹1.1 lakh
  • DSM net charge: +₹2.1 lakh
  • Loss factor unchanged: 0
  • Banking position: nil (no captive injection this period)
  • Total variance: +₹3.7 lakh — 3.4% of expected billed stack, plus the ₹2.1 lakh DSM that wasn’t in the original build-up

A clean reconciliation surfaces each delta with a code: TARIFF_REVISION, NODE_RECLASS, TRUE_UP_RETROACTIVE, DSM_DEVIATION. Without the rail-by-rail tie, the procurement team sees only the ₹7.6 lakh aggregate overshoot and has no defensible response when the CFO asks what happened.

Interactive Tool

Quantify the cost of an unmatched transmission stack

For procurement and energy-management teams running open-access at scale, the three-way match estimator quantifies the rupee value of exceptions you currently chase by email — schedule vs trader confirmation vs bill — and the analyst hours sunk into them.

Open the exception cost calculator →

What are the operational controls that close the gap?

A procurement team running a clean transmission reconciliation does six things:

  1. Quarterly PoC rate refresh under change control — the CTU notification lands a week before the quarter starts; ingest it into the rate table before the first schedule of the new quarter is filed.
  2. Tariff order register with effective-from / effective-to dates — SERC orders for STU, wheeling, CSS, and AS each carry an effective date. Mid-year true-up orders revise rates retroactively; the register has to support retroactive re-billing.
  3. Schedule-to-trade tie at settlement-period granularity — 15-minute blocks, node-coded both sides. Errors caught at filing time cost nothing; errors caught at bill time cost the DSM premium.
  4. REA ingest per settlement period — POSOCO publishes the Regional Energy Account on a settlement cycle; ingest it for the variance bridge against trader confirmation.
  5. Banking ledger by slot — injection MWh banked, drawal MWh withdrawn against bank, banking charge in kind, time-window expiry. Stale balances lapse at month-end in most states.
  6. DSM exception triage — every settlement period with a non-zero deviation is logged with cause code (source-plant deviation, grid event, scheduling error). The DSM bill then ties period-by-period.

These are operational controls, not technology controls. The reconciliation layer makes them auditable and chase-able. Without the layer, the controls degrade to spreadsheet snapshots and the 4-7% variance band drifts toward double digits.

How does transmission reconciliation interact with the broader power-utility stack?

A 10 MW open-access consumer does not run transmission in isolation. The same consumer carries:

The transmission reconciliation is one rail in a four-rail power-utility close — energy, transmission, statutory duty, and deviation. A clean rail-by-rail tie is what auditors look for on a CARO 2020 walk-through for a power-intensive manufacturer, and what the procurement committee needs when defending the open-access vs DISCOM-tariff variance to the board.

Continue reading in the Power & Utility cluster

Primary reference: Grid Controller of India (POSOCO) — for inter-state transmission system operations, PoC framework implementation, and Regional Energy Account guidance under the CERC Sharing Regulations 2020.

Frequently Asked Questions

What is the CTU and how does PGCIL bill open-access consumers under the PoC framework?
The Central Transmission Utility (CTU) is the entity responsible for inter-state transmission planning, system operation coordination, and billing of the Inter-State Transmission System (ISTS) charges. Power Grid Corporation of India Ltd (PGCIL) is the deemed CTU under Section 38 of the Electricity Act 2003. Billing follows the Point of Connection (PoC) framework under the CERC Sharing Regulations 2020 (and subsequent amendments): the Yearly Transmission Charges (YTC) of all ISTS licensees are pooled and allocated to withdrawal and injection nodes based on a node-wise PoC rate published quarterly. An open-access consumer drawing power at a withdrawal node pays the applicable PoC rate (₹/MW/month for long-term and medium-term, ₹/MWh for short-term open access) multiplied by its scheduled drawal, plus its share of transmission losses billed in energy terms.
How is STU wheeling different from CTU PoC charges?
STU charges are levied by the State Transmission Utility — MSETCL in Maharashtra, TANTRANSCO in Tamil Nadu, KPTCL in Karnataka, GETCO in Gujarat — for use of the intra-state transmission network from the state periphery to the consumer's connection point. Wheeling charges are levied by the state DISCOM for use of its sub-transmission and distribution network where applicable. CTU PoC covers only the inter-state segment; once power lands at the state periphery, the STU and wheeling tariffs (set by the respective State Electricity Regulatory Commission) take over. A 10 MW industrial consumer in Pune drawing from an IEX inter-state trade pays PGCIL PoC plus MSETCL transmission charges plus MSEDCL wheeling charges — three separate bills on different cycles.
What is cross-subsidy surcharge and when does additional surcharge apply?
Cross-subsidy surcharge (CSS) and additional surcharge (AS) are levied on open-access consumers under Section 42 of the Electricity Act 2003. CSS compensates the host DISCOM for the cross-subsidy it loses when a large industrial consumer (who would otherwise pay a subsidising tariff) sources power from outside the DISCOM. AS compensates the DISCOM for the stranded fixed cost of capacity tied up under long-term PPAs that the DISCOM cannot avoid when the open-access consumer migrates. Both are determined by the State Commission, vary by state and consumer category, and are typically billed monthly along with the wheeling invoice. Reconciliation requires the State Commission's current CSS/AS order on file with effective-date tracking — rates change annually.
How do banking charges work when an open-access consumer carries surplus from one slot to another?
Most state regulations permit an open-access consumer (typically captive or wind/solar generator) to bank surplus energy with the DISCOM for withdrawal in a later time-of-day slot or settlement period. Banking comes with a charge — usually a percentage of the banked energy retained by the DISCOM as banking charges (commonly 2% to 8% depending on state, slot, and tariff order), and time-window restrictions on when banked energy can be drawn back. Reconciliation has to track injection energy banked, drawal energy claimed against bank, banking charge in kind, expiry of the banking window, and the residual that lapses or is settled at the state-defined Average Power Purchase Cost (APPC).
What transmission loss treatment applies and how is it reconciled in the Regional Energy Account?
Transmission losses on the inter-state system are billed in energy (kWh), not rupees — the open-access consumer is required to inject (or arrange injection of) additional energy at the source node to compensate for the loss between injection and withdrawal. POSOCO's Regional Load Despatch Centre publishes a Regional Energy Account (REA) for each settlement period showing scheduled vs actual drawal by entity, deviation, and loss apportionment. The applicable POC loss factor for the withdrawal region is applied to the scheduled drawal — for example, a 5% loss factor on a 10 MW × 720-hour monthly schedule means the consumer must arrange injection of 7,560 MWh against a drawal of 7,200 MWh. Variance from the REA against the trader's confirmation and the IEX schedule is the principal reconciliation rail.

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