Commercial and industrial (C&I) entities, large institutions, and residential complexes are increasingly turning to clean power solutions that offer greater cost efficiency than conventional grid tariffs. Rooftop solar has long been an attractive option for reducing operating expenses and enhancing sustainability credentials. However, beyond on-site installations, solar open access is rapidly emerging as a scalable alternative, enabling businesses to procure renewable energy at larger volumes while optimizing long-term cost savings.

Growth of Open Access Across the C&I Segment

Tamil Nadu has emerged as a strong market for solar open access, with approximately 2.7 GW installed as of September 2025, accounting for nearly 9.6% of India’s total installations. The state’s supportive regulatory framework, combined with a growing portfolio of hybrid (solar + wind) projects, has made it an attractive destination for C&I consumers seeking reliable and competitively priced green power.

Rahul Makahaniya, Chief Marketing Officer at Soleos Energy, shares that before opting to procure green energy via open access, companies must decide on the appropriate procurement model – captive, group captive, or third-party. The group captive model, which is widely preferred, requires consumers to hold at least 26% equity in the project and commit to a long-term power purchase agreement (PPA), typically with a 12–15-year lock-in. Key commercial considerations include the PPA tariff, equity contribution, lock-in period, and termination clauses.

He added that the process from feasibility assessment and term sheet execution to land acquisition, regulatory approvals, construction, and commissioning typically takes eight to twelve months.

“Tamil Nadu is also among the leading states in India in terms of strong solar irradiation levels. Solar projects in the state generally generate around 1.4-1.5 million units annually, with a capacity utilization factor (CUF) of 17–19%, ensuring strong generation performance and predictable returns,” Makahaniya added.

While the transition to solar energy is central to advancing a low-carbon future while supporting economic growth, electrical systems play a critical role in efficiently capturing, converting, and distributing solar power.

In the utility-scale segment, the overriding objective is to continuously improve efficiency and reduce the Levelized Cost of Energy (LCOE). Every component is evaluated for its ability to minimize losses and enhance project returns.

The Balance of System (BOS) encompasses all components of a photovoltaic system beyond the solar modules, including inverters, mounting structures, transformers, switchgear, earthing, and cables. These elements are essential for converting DC power to AC, ensuring operational safety, optimizing energy yield, and maintaining long-term system reliability.

“C&I customers are increasingly adopting open access solar solutions. We have supplied over 40 GW of switchgears across open-access, rooftop solar, and utility-scale projects,” said Suresh R, Senior Manager, Lauritz Knudsen Electrical & Automation.

Depending on project design and scale, BoS components can account for roughly 20–30% of project cost, making them a critical determinant of overall return on investment. Improper sizing or poor-quality BoS design can result in transmission losses and reduced delivered energy.

“When selecting switchgear, transformers, and other equipment, the design must align with the specific project size, which varies from customer to customer. Solar infrastructure cannot be approached with a copy-and-paste methodology; each project requires customized engineering based on inverter output, system capacity, and grid requirements. Appropriate BoS selection has a direct impact on efficiency, reliability, and long-term financial performance,” Suresh added.

Rise of Energy Storage

As renewable energy adoption accelerates across India, battery energy storage systems (BESS) are emerging as enablers. What began as a complementary technology to solar and wind is fast evolving into a strategic asset for businesses seeking enhanced energy reliability, peak load management, and long-term cost optimization.

Makahaniya said, “Some states have already introduced or drafted mandates requiring storage integration. Storage currently adds approximately ₹2 (~$0.022)/kWh to ₹2.5 (~$0.027)/kWh above solar tariffs, which may limit its attractiveness without policy mandates. However, storage becomes viable in specific scenarios such as for data centers requiring round-the-clock renewable power, high-tariff consumers like hotels and hospitals, or as a replacement for expensive diesel generation.”

Overall, clean power purchase is no longer driven solely by environmental considerations. It is a strategic financial decision that enables businesses to reduce electricity costs, manage long-term risk, and move toward sustainability goals.

To truly optimize savings, companies must carefully select the right procurement model, ensure sound technical design, especially for BoS components, and evaluate the role of storage based on policy and operational needs.

On the changing face of BoS for solar plus BESS, Suresh noted that the voltage system used in residential rooftop installations is 15 volts, whereas the ground-mount system currently operates at 800 volts. And with BESS, there are other components besides LV panels, medium-voltage panels, transformers, and cables. The additional components are an isolator panel, which will be included in this system. Also, there will be a power conversion system (PCS), a battery management system, and an energy management system.

“For solar with BESS, there are both AC and DC couplings. Most go with AC coupling, but DC coupling is the future. In solar-plus-BESS, the AC part of the transformer is connected to the isolator panel, then to the PCS system, and finally to the BESS containers. When we use a DC coupling system, the DC generation can be fed directly to the isolation panel and then to the BESS. These are the additional components that come with BoS,” Suresh added.

Savings Drive Growth of BESS

Regarding the loss of savings owing to delays in approvals for open access projects, Makahaniya said, “If a company is planning a 1 MW solar project, the typical savings they will be realizing compared to the grid tariff is around ₹3 (~$0.033)/kWh. Considering solar energy generation of 1.5 million units annually, the annual savings will be around ₹4.5 million (~$49,686). If the adoption is delayed by six months, the customer loses nearly ₹2.4 million (~$26,499) in savings, which is far greater than the cost savings in case of a reduction in module and other component prices.”

Commenting on the savings for solar plus BESS, he said, “Take the case of the cement industry, automobile industry, or data centers, which run 24×7, they pay ₹15 (~$0.16)/kWh-₹16 (~$0.17)/kWh to procure power. If they use solar plus BESS as an entire replacement for a commercial unit, it is definitely viable. The cost of solar is around ₹3 (~$0.033)/kWh to ₹4 (~$0.044)/kWh, and adding another ₹2 (~$0.022)/kWh for BESS saves around ₹10 (~$0.11)/kWh, which is a big number. This explains the growing popularity of solar plus BESS among commercial consumers.”

Another aspect of BESS is the replacement of diesel generator (DG) sets. Traditionally used for backup power during outages or peak demand, DGs incur high operating costs. In contrast, BESS charging from renewable energy or the grid can significantly lower backup power costs.

Makahaniya noted, “When you generate power through DG sets, it costs ₹18 (~$0.19)-₹24 (~$0.27)/kWh. So rather than doing that, consumers can deploy BESS, which is nearly ₹8 (~$0.088)/kWh cheaper than DG sets, which is a big saving.”

“BESS is completely viable if power cuts are very common. If the power cut happens once a month, then the capital cost is too high, and you don’t need to go for it. So, these are the factors that should be looked into before replacing DG sets with BESS,” he added.

At Mercom India’s C&I Clean Energy Meet in Coimbatore, experts highlighted that rising electricity tariffs, evolving regulations, and higher savings are making renewable energy a strategic choice for C&I consumers.

The main takeaway was the growing demand for open access and BESS as viable alternatives to rooftop solar for C&I consumers, especially in Tamil Nadu.

Industry experts noted that while storage may not yet deliver immediate returns, it is steadily becoming integral to the energy landscape, driven primarily by the need for grid stability, savings, and greater renewable integration.

For certain segments, particularly high-tariff consumers and diesel-dependent users, BESS is already offering a clear economic advantage. As solar open access expands, storage is fast changing from a future consideration to a necessity in the C&I energy mix.

The next Mercom India C&I Clean Energy Meet event will be held in Bhopal on March 13, 2026.