Solar for Sugar Mills: Sizing, Roof, Approvals and Payback (50 kW+)

A sugar mill should size solar to the electricity it buys from the grid in daytime, not to its crushing-season consumption. If the mill runs a bagasse cogeneration plant, it generates its own power while crushing and often exports the surplus, so the bill solar can offset sits mostly in the off-season, plus any distillery that runs all year. Size to that, within the sanctioned load.

What does a sugar mill buy from the grid, and when?

A sugar mill's load is the most seasonal in industry. During the crushing season the mill, boilers and turbo-alternator run round the clock on bagasse, and a mill with cogeneration typically meets its own load and exports surplus to the grid. MNRE's support scheme for bagasse cogeneration was written around the surplus exportable capacity of such plants. After crushing ends the plant goes into overhaul, steam and the turbo-alternator stop, and the mill imports from the grid for workshops, water pumping, offices, the colony and whatever else keeps running. Your own crushing calendar, not a generic one, decides the months. The table is a reading guide for your own import data.

How do you size the plant?

1. Pull twelve months of import bills and, if the meter allows, half-hourly import data. Mark the crushing months separately.
2. Read the sanctioned load or contract demand, and the terms of any power purchase or export agreement for the cogeneration plant. Some agreements and connection approvals restrict additional generation behind the same point; read yours before you design.
3. Find the daytime base load you import in the off-season and from any year-round unit, in the quietest month.
4. Choose a plant whose peak output sits at or below that base load, so nearly every unit offsets an import.
5. Check land and roof area: about 100 square feet of shadow-free roof per kW, or 3.5 to 5 acres per MW on the ground, per our size pages.

The solar calculator turns a bill into a plant size and the sanctioned load calculator tests the limit. If the mill exports in the crushing season, our guide to energy banking rules by state explains what happens to surplus units. The wider point is that solar never replaces the boiler and turbine: it does not make steam, so it does nothing for the process heat load.

Roof or land, and what does a sugar-mill site do to modules?

Sugar mills usually have more land than roof: cane yards, spare plots, ash and bagasse stores, and colony land. A ground array on spare land avoids the roof and its structural question and fits above 500 kW; our guide to ground-mount solar on factory land sets out the land checks. Keep it clear of stack fall-out and of the cane-carrier shadow lines.

The site is hard on modules. Boiler stacks drop fly ash and bagasse dust, which soils glass and cuts output; open molasses and bagasse stores add organic dust. If your process uses sulphur dioxide for sulphitation, ask for corrosion-resistant coatings on structures, clamps and cable routes near the process house. Place arrays upwind of the stacks where you can, and put a cleaning method and frequency into the O&M scope; our note on module cleaning for a 1 MW plant shows the soiling maths. Bagasse stores are also a fire hazard, so keep the array and its cabling away from them and ask your fire consultant to check the layout.

Which approval route applies?

The Ministry of Power's 2021 amendment raised the net-metering limit to 500 kW, and states set the details. A mill up to that size, inside its sanctioned load, is a net-metering case with the DISCOM. Most mills will want more, and the choices are a behind-the-meter captive plant, or a captive or open-access arrangement. The Green Energy Open Access Rules, 2022 lowered the open-access threshold to 100 kW and provide for approval in 15 days or deemed approval. Our open-access solar page sets out the charges, and the captive versus open access comparison covers a 1 MW consumer.

Module rules follow the route. Under MNRE's memorandum of 4 August 2026, net-metering and open-access projects need ALMM List-I modules, and List-II cells if commissioned after 31 December 2026. A private behind-the-meter plant used solely for captive consumption is outside both lists, except where the owner is a Government entity or a public sector enterprise, so a state-owned or state-controlled mill should confirm its status before it assumes the exemption. See our ALMM guide.

The CPCB sector list, in the version dated 24 August 2026, classes sugar (excluding khandsari and jaggery) as Red and solar photovoltaic generation as White. A solar plant does not change the mill's category, but check whether your consent conditions need updating; see consent to establish and operate. A plant at 11 kV or above also needs the connection works and inspection described in our guide to connecting at 11 kV.

What risks are specific to sugar mills, and how does payback work?

The main risk is a plant sized to the wrong period. A plant sized against the crushing-season load will sit mostly idle against a small off-season import and export the rest at a lower price, if the connection allows export at all. The second is the interface with cogeneration: protection settings, synchronisation and metering must be agreed so that two generators behind one meter do not trip each other; our note on solar with DG sets sets out the logic, which applies to any on-site generator. The third is the value of a unit: solar offsets an imported unit at the grid tariff, which typically differs from the price paid for exported cogeneration power.

On cost, our published band for rooftop C&I solar is ₹24,000–32,000 per kW excluding GST, indicatively ₹28–32 lakh at 100 kW and ₹68–75 lakh at 250 kW on our size pages; a ground array is priced differently, so ask for foundations, fencing and the cable run itemised. Payback is the capital cost against the import bill you stop paying, counted over the months you actually import. Test it with your own tariff in the solar payback calculator.

How Secured Engineers helps

We design C&I solar in-house, file DISCOM net-metering, Fire NOC and CEIG applications in-house, and deliver MEPF and solar under one contract, which matters on a process site where the electrical room, the fire system and the water systems share the same footprint. We work from offices in Noida (Delhi NCR) and Ludhiana, with 535+ projects across 18+ states and 89.77% repeat clients.

Send twelve months of import bills, the sanctioned load, the crushing calendar and a land or roof drawing, and we will show the plant size your import load supports and the route that applies. See our solar for factories page, message us on WhatsApp, call +91 70099 85817, or ask for a free proposal.