Solar for Auto-Component Plants: Sizing, Roof, Approvals and Payback (50 kW+)

An auto-component plant can usually put 50 kW or more of rooftop solar to work because press, CNC and machining loads run through the solar day. Size the plant from your monthly bills: find the daytime share of consumption, cap the capacity at what the roof, the sanctioned load and the transformer allow, then test the payback. Weekend and holiday shutdowns decide how much you can export or must curtail.

What is specific about an auto-component plant

Four features of the sector shape the design, and each differs from a generic factory.

• Heavy daytime machine load. Presses, CNC and VMC machines, grinders and compressors draw power through the day, so a large share of the consumption falls in solar hours. That is the strongest fit for self-consumption.
• Two-shift working. A plant running two shifts covers the whole solar day and then some. The evening shift and any night work are not served by solar, which sets a ceiling on how much of your bill it can offset.
• Large sheds. Press shops and machining bays have big, often long-span roofs, which suit a single large array and keep cable runs short. They also carry cranes, ducts, extraction and roof ventilators that cast shadows and need clearances.
• Customer sustainability demands. Tier-1 and OEM customers increasingly ask suppliers about energy sources and emissions. A plant with metered solar generation has data to answer with. Ask your customers what evidence they want before you assume what counts.

Sizing from the bill: a method

Start with twelve months of bills, not one. The sizing steps below turn them into a capacity you can defend. The solar calculator follows the same logic.

The smallest of the limits in steps 2 to 5 is your design capacity. Our glossary explains sanctioned load versus connected load if the bill terms are unfamiliar.

Roof or ground, and what the roof must carry

Most plants of this kind use the shed roofs. Check the roof sheeting and purlin condition, the age of the structure, the load allowance from the original design, and whether the roof has fragile skylights that need walkways or covers. Long-span sheds of this type often take lightweight clamp-on mounting; RCC roofs on office blocks need anchored or ballasted structures. A structural engineer's check before design is cheap against the cost of a leaking or overloaded roof, and the roof load calculator gives a first idea of the added load.

Where the roofs are shaded, fragmented or near the end of their life, ground-mount on spare industrial land is an alternative, at the cost of foundations, fencing and longer evacuation cables. Both routes can coexist.

Which approval route applies

The route depends on the size and the connection. The Ministry of Power's year-end review records that the net-metering limit was raised from 10 kW to 500 kW by an amendment of 29 September 2021, and state commissions fix the detail, so a plant up to about 500 kW at an HT or LT connection often goes the net-metering route, within the sanctioned-load rule of the state. Larger plants, or plants that cannot export, move to a captive arrangement, gross metering, or open access. Open access for green energy is allowed from 100 kW of contract demand under the Green Energy Open Access Rules, 2022, which the Ministry of Power announced with a 15-day approval clock. Our open access solar page compares the options.

Alongside the DISCOM application you will need the electrical inspector's approval of the installation. See our CEIG approval guide. As of October 2026, ALMM List-II (solar cells) is waived for net-metering and open-access plants commissioned by 31 December 2026, and does not apply to behind-the-meter plants used solely for captive consumption; the MNRE O.M. of 4 August 2026 has the wording. Ask your supplier to state which regime your project falls under.

Risks that are specific to the sector

• Dust, oil mist and coolant vapour. Machining and heat-treatment bays foul module surfaces; agree a cleaning schedule and water arrangement before commissioning.
• Shadows from the plant itself. Exhaust stacks, extraction ducts, cooling towers and crane gantries.
• Press and welding loads. Fluctuating loads and harmonics stress power quality; ask for a power-quality check and for inverter settings to suit your power factor correction.
• Roof access during production. Crane and material movement in shed bays limits installation windows; plan around shutdowns.
• Production changes. A new line or shift pattern changes the daytime share; size with some headroom, not at the exact limit.
• DG interlock. A plant that back-feeds a DG set during an outage damages it; the changeover logic is part of the scope.

Payback logic using the published benchmark band

Our published band for commercial and industrial solar is ₹24,000 to 32,000 per kW excluding GST, with larger plants towards the lower end, and it is indicative until a site survey. Simple payback is the installed cost divided by the yearly value of the units the plant displaces. The yearly value is annual generation, times the share your load uses, times the retail tariff those units would have cost, less operations and cleaning. Exports, if allowed, are valued at the rate the state sets and not at your retail tariff, which is why the self-use share matters most. Use the calculator with your own tariff, and run the sensitivity at a lower self-use share to see how the answer moves.

How Secured Engineers helps

We design in-house and file Fire NOC, CEIG and DISCOM net-metering applications in-house, so a plant on an auto-component shed is designed with the inspector's and DISCOM's requirements in view. MEPF and solar can sit under one contract, which helps where the same shutdown covers roof work and electrical changes. We work from offices in Noida (Delhi NCR) and Ludhiana, with 535+ projects across 18+ states and 89.77% repeat clients.

If you are weighing a 50 kW+ plant, send twelve months of bills and a roof plan. See our solar for factories page, message us on WhatsApp, call +91 70099 85817, or ask for a free proposal.