Maharashtra's Solar Banking Order Costs One Site ₹32.62 Lakh a Year

₹32.62 lakh a year. That is what one rule change costs one solar site in Maharashtra: same plant, same load, same tariff, just the banking order that took effect on 25 March 2026.

The rule is short. Units banked during solar hours can only be drawn back during solar hours: not overnight, not at peak. Banking settles every month, and unused credit lapses. Applying its own formula, the regulator priced the value of banking at nil.

Why most sizing tools now get it wrong

Most sizing tools still model banking as an annual net, where surplus units are simply offset against consumption over the year. Under this order that is wrong in three separate places, and each one changes the battery you would quote:

• When units can come back: banked energy is restricted to solar hours, not any hour.
• How often it settles: monthly, not annually, with unused credit lapsing.
• How the charge is taken: in energy rather than in rupees.

How Ingro Sims models the order

Ingro Sims rebuilt banking as what it actually is now: a permission matrix, a monthly ledger and a charge taken in energy rather than rupees. Turn banking on, and the sizing re-runs against the order. Sims then shows where every unit went.

On this run:

• 1,280 MWh was generated.
• Only 2.14 MWh ever reached the grid bank.
• 1.66 MWh came back.
• 309 kWh lapsed.

The real lesson: properly sized storage makes banking rare

That last number is the point. Once storage is sized properly, banking barely happens, which is exactly what the order was designed to do. Solar that would once have been parked in the grid bank is now shifted on site by the battery. For anyone quoting solar in Maharashtra, banking can no longer be treated as a free annual buffer, and the storage size has to be worked out against the order as written.