Mumbai, Sept. 9 -- The value of solar now lies not only in daytime offset but in the ability to deploy energy when required, writes Rounak Muthiyan.
Having worked in power systems for over two and a half decades, one truth has remained constant: unless the economics make sense, no new technology can sustain itself. India's solar journey has evolved from an energy-deficit era to one of adequacy and, increasingly, renewable surplus. And this shift has played out differently across regions and states.
India's rooftop solar installed base has grown from 1.8 GW in FY2019 to more than 17 GW by FY2025, with 7.1 GW added in 2025 alone. Solar now contributes close to 10 per cent of India's total electricity generation. India today adds nearly 60 GW of power capacity annually, the equivalent of a European country's installed base. At that pace, grid dynamics change, and regulators in high-penetration states are rethinking the terms that enabled this growth. As the grid hits absorption limits, policy mechanisms that once rewarded simple generation are now forcing a pivot toward dispatchable, round-the-clock reliability.
Maharashtra's evolving time-of-day framework is the most visible sign of this shift. The transition creates complexity for existing projects and stakeholders, particularly those who made commitments under the previous settlement structure. But the underlying question is clear: what does a truly grid-integrated, commercially self-sustaining model for solar look like? The answer is storage.
On-Demand Deployment
Conversations with commercial & industrial (C&I) customers reveal a striking consistency: most have concluded that banking from the grid was always on borrowed time. The value of solar installations now lies not just in daytime generation offset but in the ability to deploy energy when required.
Customers who built their investment cases around banking excess energy are now looking at Maharashtra's evening industrial tariffs, ranging from Rs.12.50 to over Rs.22 per unit, and recognising that the arbitrage case for storage is structurally stronger than anything the old model offered. Storage completes the original value proposition, shifting solar from a partial solution to a dispatchable one.
Battery costs have fallen approximately 80 per cent over the past decade, reaching around Rs.1.7 million per MWh in 2025. Utility grid solar-plus-storage auctions in 2025 cleared at Rs.3.9-Rs.6.5 per kWh for two-hour battery configurations. For industrial customers in Maharashtra, a well-structured solar-plus-storage system delivers daytime power at around Rs.5.50-6.50 per unit, versus grid tariffs of approximately Rs.8.50-12.50. Where peak evening tariffs exceed Rs.22 per unit, the economics are even stronger.
At current battery prices, such projects deliver a payback period of about six years and an internal rate of return (IRR) of 14-16 per cent, driven purely by energy economics. With battery costs declining by 40 per cent in 2024 and a further 31 per cent in 2025, IRRs above 20 per cent are possible within the next 24 months. We are moving from a technology that required belief to one that only requires a calculator.
Beyond arbitrage, battery assets create compounding value through revenue stacking: peak demand charge reduction, improved load management, and, as India's grid services market matures, potential participation in ancillary services.
Rooftop Recast
The decisive moment is when a C&I customer concludes, on purely commercial grounds, that solar-plus-storage delivers cheaper and more reliable power than the grid across 15-20 hours of the day. That decision, made at scale, is what moves India's energy transition from a government-led programme to a market-driven one.
Maharashtra, with its industrial density, auto ancillary clusters, tech parks and manufacturing belts, is reshaping how rooftop solar is priced and valued. It has the conditions to be the state where the proof of concept emerges first. Maharashtra led the country in rooftop capacity additions in 2025, accounting for 16 per cent of national installations. That is a foundation. Storage raises the ceiling on what that foundation can deliver.
The C&I segment accounts for roughly 18 per cent of India's rooftop solar additions today. As storage economics improve and more customers move from evaluation to execution, that proportion, and the sophistication of those projects, is likely to change materially.
The transition does carry complexity for stakeholders with existing commitments, but structured support during this period is warranted. However, the broader direction is not a matter of opinion. Dispatchable renewables and storage-integrated solar for the C&I segment is where technology costs and grid economics are converging. The question for every industrial and commercial energy consumer in India today is not whether to make this transition; it is how quickly they can move.
ABOUT THE AUTHOR:
Rounak Muthiyan, Founder & Director of Kalpa Power, has steered one of India's top five solar EPC firms to commission over 300 MWp of capacity since 2017, with an additional 125 MWp in the pipeline.
Published by HT Digital Content Services with permission from Infrastructure Today.