Open access solar is one of the most cost-effective mechanisms for large C&I consumers to reduce their electricity bills — but the economics vary dramatically from state to state, and the regulatory landscape changes frequently. This guide covers the applicable charges and regulatory framework for five key states in 2025.
Understanding the charge structure
An open access solar project involves generating power at one location (the solar plant) and consuming it at another (the industrial or commercial facility), using the state's distribution and transmission network as the carrier. The charges levied for this service determine whether the open access economics are positive.
The primary charges are:
- Wheeling charges: The per-unit charge for using the DISCOM network to carry the power from generation point to consumption point
- Cross-subsidy surcharge (CSS): A charge levied to compensate the DISCOM for the revenue it loses when a large consumer exits its supply
- Transmission charges: For projects using the state transmission network (above the DISCOM level)
- Banking charges: If the project owner wants to bank excess generation and draw it back later (subject to state-specific limits), a banking charge applies
- Reactive energy charges: For maintaining required power factor at the consumption point
Rajasthan
Rajasthan is one of the most attractive states for open access solar due to its high irradiance and relatively lower CSS. The state's renewable energy open access framework allows banking of energy for up to one month, with a banking charge of typically 2% of banked units. Wheeling charges are levied at DISCOM rates for intrastate projects. CSS has been a point of regulatory uncertainty — it was waived for renewable energy open access projects in earlier years, and C&I consumers should verify the current applicable rate with RERC before financial modelling.
Gujarat
Gujarat's open access framework is well-established, and the state has a clear regulatory process for open access approvals. Wheeling charges vary by voltage level (HT consumers at 33 kV attract lower wheeling rates than LT consumers). Banking of solar energy is permitted quarterly, with banking charges of approximately 5% of banked units. CSS in Gujarat has been among the higher rates nationally — a significant factor in project economics that must be modelled carefully.
Karnataka
KERC has historically been supportive of open access solar, and Karnataka's high industrial power tariffs make the economics of open access particularly attractive. However, CSS has been a source of dispute between open access consumers and BESCOM, with surcharge rates revised periodically. Banking is permitted on a monthly basis. C&I consumers in Karnataka should verify current CSS rates under the applicable KERC tariff order before committing to project economics.
Maharashtra
Maharashtra (MSEDCL jurisdiction) has active open access solar development, particularly in the Pune and Nashik industrial corridors. The state levies wheeling charges, CSS, and standby charges. A notable feature of the Maharashtra framework is the standby charge — levied for the backup supply capacity that the DISCOM must maintain even when the open access consumer is drawing from its own solar plant. This charge can be significant and is often overlooked in initial economic assessments.
Tamil Nadu
TANGEDCO has processed a significant volume of open access approvals for C&I consumers in the automotive, textile, and technology sectors. The state's framework includes wheeling, CSS, and transmission charges. Tamil Nadu's banking policy has been more restrictive than other states — energy banked in a given month must typically be consumed within the same month or the following month, with limited carry-forward provisions. This affects the economics of projects where generation and demand are not well-matched on a monthly basis.
Open access solar economics must always be modelled against the current regulatory order in the applicable state — not against historical rates or industry assumptions. Regulatory risk is real, and a project that is financially viable under today's open access framework may be marginal if CSS rates are revised upward after commissioning.