What Solar Alone Achieves
A rooftop solar plant in Maharashtra typically operates at a capacity utilisation factor of around 18–20%, generating roughly 1,500–1,750 units per kW annually, concentrated in about eight daylight hours.
For a single-shift facility operating from 09:00 to 18:00, a well-sized rooftop array can cover a significant share of daytime consumption. For a three-shift continuous-process plant, the same system may cover only around a third of total consumption.
Roof area is often the binding constraint. A typical 1 kW rooftop solar system requires around 90–100 sq. ft. of unshaded, structurally suitable roof space. This is one reason offsite procurement is expanding. India added close to 6 GW of solar open-access capacity in the first half of 2026, up 42% year-on-year, with Maharashtra among the top three states by cumulative capacity.
Solar's limitation is straightforward: generation stops after sunset. This is where storage adds value.
What Storage Adds
A battery can extend solar's useful hours by storing excess midday generation and discharging it when the facility needs power in the evening.
It can also reduce the cost of grid dependence. Businesses can purchase more electricity during the cheaper, rebated daytime window and use stored energy during expensive evening hours. While the reduction in grid consumption may be moderate, the reduction in the electricity bill can be considerably greater.
Storage can also provide backup during short outages, which account for many interruptions at industrial sites. Stored energy can often replace diesel generator usage, which can cost around ₹18–30 per kWh.
A Worked Illustration
Consider a Maharashtra manufacturing unit with 2,000 kVA contracted demand, operating two shifts and consuming approximately 800,000 units per month, with around 30% of consumption occurring after 17:00.
A 1 MW rooftop solar plant could generate around 145,000 units per month. If most generation is self-consumed during working hours, it could displace approximately 18% of total consumption without storage.
Adding a 1 MW/2 MWh battery, with one full cycle per day across 300 operating days, could shift around 600,000 units annually from daytime to evening. The system could also potentially reduce recorded maximum demand by 400–500 kVA. With HT demand charges rising from ₹600 to ₹750 per kVA per month, demand reduction creates an additional recurring saving.
The combined system could potentially displace 25–30% of grid energy, while reducing a substantially larger share of grid costs because the most expensive units are disproportionately displaced.
Why Full Independence Is Usually Not the Target
Moving from 30% to 60% grid displacement can be economically attractive. Moving from 60% to 95% is considerably more expensive.
Seasonal variability is a major reason. Designing for the worst monsoon week could require storage capacity that remains underutilised for much of the year. The marginal value of additional storage declines as the system becomes larger.
Maharashtra's policy also provides incentives for grid-connected storage, including exemptions from certain transmission charges, distribution demand charges, electricity duty and cross-subsidy surcharge where qualifying energy is consumed within the state. Captive projects with at least four hours of storage covering 50% of contracted renewable capacity can also qualify for a 10-year electricity duty exemption.
Where Near-Independence Makes Sense
Larger systems can make sense for sites with poor grid reliability, remote operations, heavy diesel dependence or critical loads where outages carry significant financial consequences. Data centres, hospitals, metro stations and airports are among the segments expected to see strong C&I storage growth through 2032.
The right approach is to separate cost reduction from supply resilience. For cost savings, size solar and storage around the load profile and tariff. For resilience, size backup around critical loads and realistic outage durations.
For most businesses, the grid should not be viewed as the problem. Uncontrolled exposure to expensive peak-hour power is. A right-sized solar-plus-BESS system can reduce both grid consumption and, more importantly, the cost of remaining grid-dependent.
