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Open access is a real cost-saving lever for eligible industrial consumers in AP and Telangana, but the terminology around it — STOA, LTOA, wheeling, CSS, group captive — trips people up before they even get to the savings question. Here is the practical version.
Short-term open access (STOA) covers periods from a single day up to about a month at a time, filed and scheduled with the SLDC on a rolling basis. Long-term open access (LTOA) is a multi-year commitment with its own application process and different priority in transmission allocation. The choice is less about product type and more about how much scheduling flexibility versus long-term price certainty a consumer wants.
The State Load Despatch Centre approves applications and manages the day-ahead and intra-day scheduling that makes open access power actually flow. Every open access transaction — regardless of which generator or trader is on the other side — has to be scheduled through the SLDC, which is why ongoing scheduling coordination, not just the initial approval, is a real part of the workload.
Open access only makes financial sense once wheeling charges (for using the DISCOM network) and cross-subsidy surcharge are netted against the price advantage of the sourced power. APERC and TGERC publish these rates in their tariff orders, and they change periodically — a savings estimate that does not reference the current tariff order is not a reliable one.
Source: APERCGroup captive is a different route: the consumer (or group of consumers) takes at least 26% equity in the generating plant and consumes at least 51% of its output, which qualifies the arrangement for captive status and exempts it from cross-subsidy surcharge. In high-CSS states like AP and Telangana, group captive is often the more economical structure for consumers who can commit the equity, while pure open access suits those who want a shorter-term or more flexible arrangement without an equity commitment.
When the generator sits outside the state, the transaction moves from state open access to ISTS (inter-state transmission system) open access — regulated by CERC rather than the state commission, with NLDC and the regional load despatch centre added to the scheduling chain. Renewable power sourced this way currently benefits from a waiver on ISTS transmission charges, which is a major reason ISTS open access for solar or wind can be more competitive than it first appears once conventional generation is compared on the same route.
Open access is generally available to consumers above roughly 1 MW contracted demand, though the exact eligibility and category-wise rules are set by the state commission (APERC or TGERC) and can vary by consumer category.
Yes — open access is not a one-time approval. It requires ongoing monthly scheduling, billing reconciliation, and periodic renewal to remain valid, alongside compliance with any deviation settlement mechanism (DSM) obligations.
