Why 4-Hour Storage Can Beat Maharashtra's 2-Hour Minimum on Payback
Maharashtra's floor is 1 MWh of storage per MW of new solar. Doubling to 2 MWh/MW unlocks a 10-year electricity-duty exemption for qualifying captive projects; on a 667 kW analysis the 4-hour build broke even in 4.2 years and finished ₹1.9 Cr ahead.
Maharashtra has changed the maths on every new solar plant above 100 kW. Since April 2026, storage is no longer optional: it is the price of connecting to the grid. The floor is 1 MWh of storage per MW of solar.
Most developers stop there. That is where the more interesting decision starts.
The option most developers are missing
Double the storage to 2 MWh per MW, a 4-hour build instead of the 2-hour minimum, and qualifying captive projects unlock a 10-year electricity-duty exemption on the power they supply.
The result is the same plant with two very different 10-year outcomes: one sized to clear the mandate, and one sized to capture the duty holiday as well.
What the numbers showed on a 667 kW plant
On a recent 667 kW analysis in Ingro Sims, the two builds compared like this:
- The 4-hour build broke even in 4.2 years, faster than the smaller mandate build.
- By year 10, the 4-hour build finished ₹1.9 Cr ahead.
The larger battery costs more up front, but the duty exemption and the extra shifted energy repay it quickly enough that it overtakes the minimum build on both payback and long-run value.
The hard part is knowing which build wins for you
The mandate itself is simple. The hard part is knowing which build wins for your tariff, your load and your consumption, because the answer will not be the same for every plant. That is what Ingro Sims was built for: modelling both builds against your own data so the decision is measured rather than assumed. Size it for your plant at sims.ingroenergy.com.
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