Not every business has the roof or the land to host enough solar to cover its load. A mid-size textile or fabrication unit in Surat might consume far more electricity than its sheds could ever generate. Open access is how those businesses still buy cheaper renewable power: instead of building a plant on-site, they contract for power from a solar or wind farm located elsewhere and have it delivered over the grid. This guide explains how it works in Gujarat, who qualifies, what it costs, and how to decide whether it fits your business.
What is open access solar?
Open access is a regulatory right that lets large electricity consumers buy power from a generator other than their DISCOM — including a third-party solar or wind plant sited away from their premises — and have that energy wheeled to them over the existing transmission and distribution network.
In plain terms: a solar farm generates power off-site, the grid carries it to your factory, and you consume it there at a tariff negotiated with the generator, usually lower and more predictable than the DISCOM's industrial rate. You pay the generator for the energy and the network operator a set of charges for using the grid to deliver it.
There are two common commercial structures:
- Third-party open access — you sign a power purchase agreement (PPA) with an independent developer who owns the plant and sells you the output.
- Captive / group-captive — you (or a group of consumers) hold an equity stake in the generating plant, which can change the regulatory treatment and some charges.
How power wheeling works
The energy is not physically routed to your meter like water through a dedicated pipe; the grid is a shared pool. Wheeling works through accounting:
- The solar plant injects its generation into the grid at its connection point.
- Your facility draws power from the grid as normal.
- The state load-despatch centre and DISCOM net your consumption against the contracted generation over a settlement period.
- You are billed for the energy at the PPA rate, plus the applicable wheeling and other open-access charges, plus the DISCOM's normal supply for anything not covered.
Because generation and consumption are reconciled over time, open access pairs naturally with solar's daytime profile — and any shortfall is simply topped up from the grid.
Who qualifies in Gujarat?
Open access is meant for higher-load commercial and industrial consumers. Eligibility is defined by a contract-demand / connected-load threshold set in state policy and regulations — historically open access has been available to consumers above a defined load (commonly referenced around the 1 MW level for inter-state and many intra-state cases, with state variations). Gujarat has an active C&I open-access market served by multiple developers.
Because the exact threshold, the categories eligible, and the procedural requirements are set by GERC and the DISCOMs (Torrent Power, GUVNL/GEB) and are periodically revised, treat any specific figure as indicative: confirm the current eligibility threshold and application process against the latest GERC and DISCOM notifications before you plan around it. Our consulting team tracks these and can check your eligibility quickly.
The charges you actually pay
The headline PPA tariff is only part of the landed cost. Open-access power carries a stack of grid-use charges, and getting the net number right is the whole game. The typical components:
| Charge | What it covers |
|---|---|
| Energy / PPA tariff | The price you pay the generator per unit |
| Wheeling charges | Use of the distribution network to deliver power |
| Transmission charges | Use of the inter-state/intra-state transmission system |
| Cross-subsidy surcharge (CSS) | Compensates the DISCOM for losing a paying C&I consumer |
| Additional surcharge | Recovers the DISCOM's stranded fixed costs, where levied |
| Banking charges / settlement terms | Cost and rules for "banking" surplus generation for later use |
| Standby / backup demand charges | For grid supply when the open-access plant under-delivers |
The cross-subsidy and additional surcharges are usually the swing factors that decide whether open access beats your grid tariff — and they are exactly the charges that change with policy. Some are waived or reduced for certain renewable or captive structures as a policy incentive, which is why two similar deals can land at very different effective tariffs.
Open-access charges, surcharge waivers and banking rules evolve with GERC orders and DISCOM circulars. Always model the landed cost per unit against the latest notification — not last year's numbers — before signing a PPA.
Why businesses use open access
- Lower energy cost. A well-structured open-access PPA can beat C&I grid tariffs, often with multi-year price certainty against rising grid rates.
- No upfront capital or roof. You contract for power, not for a plant — no land, no civil works, no capex on your balance sheet (an OPEX-style model; see capex vs opex solar).
- Scale beyond your premises. You can source far more renewable energy than your own roof or land could ever host.
- Green credentials. Verified renewable supply supports ESG reporting and RE100-style commitments.
- Hedge against tariff hikes. Locking in a generation tariff insulates a large part of your bill from DISCOM increases.
Open access vs rooftop — and why most do both
Rooftop and open access are not competitors; they cover different slices of your load.
| Rooftop solar | Open access | |
|---|---|---|
| Location | On your building | Off-site farm |
| Capital | You own the asset (or OPEX PPA) | Contract for power, no asset |
| Value of each unit | Offsets retail tariff behind the meter | Generation tariff + wheeling charges |
| Scale limit | Your roof area | Effectively your whole load |
| Grid charges | Minimal | Wheeling, transmission, surcharges |
| Best for | Daytime self-consumption | Large remaining load |
Rooftop is unbeatable for daytime self-consumption because each unit cancels a unit you would have imported at full retail tariff, with almost no grid charges. Open access shines for the balance of load that your roof cannot physically cover. A typical industrial strategy is to put solar on every viable roof, then contract open access for the rest — and increasingly to add storage on top.
Combining open access with on-site solar and storage
The strongest energy strategy for a large consumer is layered:
- Rooftop solar for the cheapest daytime units behind the meter (our solar EPC).
- Open-access PPA for the bulk of load beyond what the roof can serve.
- Battery storage / BESS to shift solar into evening peaks, manage demand charges and firm up supply — see commercial battery storage for peak shaving.
- Grid as the residual top-up and standby.
Done well, this stack drives the blended cost of energy down while protecting against both tariff hikes and intermittency. The art is sizing each layer against your real load curve so you are not over-paying for any one of them.
How to evaluate an open-access deal
Before signing, work through:
- Landed cost per unit — PPA tariff plus every grid charge and surcharge, compared to your current effective tariff. This, not the headline rate, is the real number.
- Eligibility — confirm your contract demand clears the current GERC/DISCOM threshold.
- Charge stability — understand which surcharges are fixed, which can be revised, and any waivers your structure qualifies for.
- Banking terms — how surplus generation is credited and at what cost.
- Generator track record — the plant's reliability and the developer's standing for a 10–25 year PPA.
- Exit and standby — what happens, and what it costs, when the plant under-delivers or you want to leave.
FAQ
What is the minimum load needed for open access in Gujarat?
It is set by a contract-demand threshold in state policy, historically referenced around the 1 MW level with variations. Because GERC and the DISCOMs revise these rules, confirm the current threshold against the latest notification — we can check your eligibility during a consultation.
Is open-access power actually cheaper than my grid bill?
Often, but only once you include all wheeling, transmission and cross-subsidy charges. The headline PPA tariff can look very attractive and still land close to your grid rate after surcharges, so always compare the full landed cost per unit.
Do I need to invest any capital?
No. In a third-party open-access PPA you contract for power without owning the plant — an OPEX model with no roof, land or capex required. Group-captive structures, by contrast, involve an equity stake.
Can I use open access and rooftop solar together?
Yes, and most large consumers should. Rooftop covers daytime self-consumption at the best economics; open access covers the larger remaining load your premises cannot host. Adding storage lets you shift and firm the supply further.
What happens if the solar farm under-generates?
You draw the shortfall from the grid as usual, billed at the applicable supply and standby terms. This is why backup/standby charges and banking rules matter in the contract, and why pairing open access with on-site solar and storage improves resilience.
Plan the right energy mix
Open access can take a serious bite out of a large consumer's energy cost — but only when the eligibility, charges and contract terms are modelled accurately against the latest GERC and DISCOM rules, and balanced against on-site solar and storage. SilInfra advises C&I clients across Gujarat on exactly this mix, from rooftop and ground-mount to open access and BESS. Talk to our consulting team or request an assessment to find the lowest-cost, lowest-risk route for your load.