Solar for FMCG Factories: Sizing, Roof, Approvals and Payback (50 kW+)

A solar plant for an FMCG factory should be sized to the factory's lowest sustained daytime load, not to the roof. Read twelve months of bills for daytime units, maximum demand and sanctioned load, fit the plant under that base load and the transformer's headroom, then choose the approval route by size. Payback follows from units used on site, not units generated.

How do you size solar for an FMCG factory from the bill?

FMCG plants differ from heavy industry in one useful way: most of the load is the packing hall, not a furnace. Filling, blow-moulding, labelling, shrink-wrapping and case-packing lines run in shifts, with air-conditioned or controlled areas, compressed air and often cold storage. The load follows the production plan, so the bill alone can mislead. Use this sequence.

1. Pull twelve months of bills and, if the DISCOM provides it, half-hourly meter data. You need monthly units, recorded maximum demand, sanctioned load or contract demand, and any time-of-day tariff slots.
2. Find the daytime base load. Take the lowest sustained demand between roughly 9 am and 4 pm on normal production days, not the average. Lines that stop for changeovers, lunch or a shift handover set this floor.
3. Cap the plant near that base load. A plant whose output stays below the base load means nearly every unit is used on site. Oversizing sends units to export or curtailment, which pay far less than self-use.
4. Check the sanctioned-load and transformer headroom. The DISCOM links permitted capacity to the sanctioned load and checks the distribution transformer. Our sanctioned-load calculator shows how capacity maps to load, and the glossary entry explains the terms.
5. Test the roof last. Roof area, structure and shading decide whether the plant fits, but they should not set its size. The solar calculator combines these inputs.

Seasonal products change the picture. A beverage or ice-cream line peaks in summer, when solar output is also highest; a winter-weighted line does not. Look at the year, not the month with the highest bill.

Which roof or ground option suits an FMCG site?

Most plants use the roofs of the production, packing and warehouse sheds. Pre-engineered metal roofs usually need a structural check for the extra load and a clamp-on or standing-seam mounting design, so penetrations do not become leak points. Leaks matter more in food and personal-care sheds than in a fabrication yard, because product, packaging and hygiene rules are all at risk. Where roofs carry HVAC condensers, chillers or cooling towers, keep the layout clear of exhaust plumes and walkways. Where roofs are too small or too old, carports or ground mounting on spare land are the alternatives; our note on carport solar compares them. Keep access for panel cleaning and for fire-service routes. The CEA safety regulations require clear roof pathways at least 75 cm wide with hand rails.

What approval route applies, and does size change it?

The net-metering limit is reported in the Ministry of Power's year-end review, which dates the amendment to 29 September 2021. Other sources give a different date, so rely on your state commission's current regulation, which is what governs you. Module rules also matter. MNRE's O.M. of 4 August 2026 exempts net-metering and open-access projects commissioned by 31 December 2026 from ALMM List-II (solar cells), but List-I modules still apply. It also says neither list applies to behind-the-meter solar used solely for a consumer's own captive consumption, other than government entities. Read the ALMM List-II commissioning guide before you choose modules.

What risks are specific to an FMCG plant?

• Power quality. Servo drives, VFDs on compressors and automated lines are sensitive to harmonics and voltage swings. Specify inverter harmonic limits, reactive-power control and a power-quality check at the point of connection.
• DG interlock. Many plants keep DG sets for line protection. Solar must trip or throttle when the DG is on. See our note on solar with DG sets.
• Hygiene zones. Cleaning water, bird droppings and dust near open product areas need a cleaning method agreed with the quality team. Mounting solar over roofs above exposed-product zones is a conversation to have with your food-safety lead before design, not after.
• Contract manufacturing. If you pack for brand owners, they may ask for evidence of renewable share. Metered generation data, not a modelled estimate, answers that.
• Fire. Regulation 121 of the CEA safety regulations requires fire detection and suppression systems for solar installations to meet the relevant standards. Coordinate with the plant's fire design, and see our food processing and FMCG page.

How do you work out payback?

Payback is the capital cost divided by the yearly saving. The saving is units generated, times the share used on site, times the tariff you avoid. Our solar-for-factories page uses an example of about 1,440 units per kW a year and notes that industrial tariffs sit around ₹7.5–9.5 a unit. Take a 200 kW plant at 80% self-use and ₹7.5 a unit: 288,000 units × 0.8 × ₹7.5 is about ₹17.3 lakh a year. The published C&I band of ₹24,000–32,000 per kW excluding GST puts capital at ₹48–64 lakh, so simple payback is roughly 2.8 to 3.7 years. That excludes GST, O&M, degradation and tax effects, and it moves with self-use: at 60% self-use it lengthens. The page's own benchmark is a three-to-six year band, and the calculator shows the scenarios. Use the solar for factories guide and the size pages, such as 250 kW and 500 kW, for the cost scope.

How Secured Engineers helps

Secured Engineers designs solar and the electrical systems around it in-house, and files DISCOM net-metering, CEIG and Fire NOC applications in-house. MEPF and solar can be delivered under one contract, which suits a plant adding a packing hall or cold store alongside solar. We work from offices in Noida (Delhi NCR) and Ludhiana, and have delivered 535+ projects across 18+ states, with 89.77% repeat clients.

Send twelve months of bills and a roof plan and we will size the plant from your daytime load and show the approval route. See solar for factories, then reach us on WhatsApp, call +91 70099 85817 or request a free proposal.