Solar Energy for India's Foundry & Casting Industry

Key Takeaways

• India's foundry and metal casting industry is one of the most energy-intensive manufacturing sectors — electricity and fuel together represent approximately 15–25% of casting production cost, with electricity alone 8–12%
• The average specific electricity consumption in Indian foundries is approximately 680 kWh per tonne of liquid metal; well-optimised plants achieve 500 kWh/tonne
• Solar rooftop systems of 200–800 kW are a natural fit for casting plants, given their large single-storey shed rooftops and high daytime electricity demand
• A 500 kW solar plant on a mid-size foundry in Rajkot, Coimbatore, Agra, or Delhi-NCR can save approximately ₹40–55 lakh per year at current HT industrial tariffs
• India has approximately 4,500+ foundries employing over 5 lakh workers — most of these MSMEs are paying full grid tariffs and have not yet explored solar
• Solar cannot directly power high-power induction furnaces during melting (peak loads of 1–5 MW per furnace exceed typical rooftop solar capacity), but it can offset all other plant electricity loads — compressed air, cooling, lighting, post-process equipment, offices — freeing up budget and reducing net energy cost per tonne

India is the world's second-largest producer of castings after China, with annual production exceeding 12 million tonnes across iron, steel, aluminium, copper, and zinc castings. The foundry cluster in Rajkot (Gujarat) alone has over 1,000 foundry units; other major clusters are in Coimbatore (Tamil Nadu), Agra (UP), Batala (Punjab), Howrah (West Bengal), Belgaum (Karnataka), and Pune (Maharashtra).

The sector's energy challenge is well-known: melting metal requires enormous amounts of electricity or fuel. For the majority of Indian foundries using electric induction furnaces, electricity is the dominant variable cost — and grid tariff increases over the past five years have significantly eroded margins. Solar energy offers a partial but meaningful solution.

How Electricity Is Consumed in a Foundry

Understanding the energy profile of a casting plant is essential for sizing a solar system correctly.

1. Melting (Induction Furnaces) — the Dominant Load

For foundries using coreless induction furnaces (the most common type in India), melting accounts for approximately 60–75% of total electricity consumption. Induction furnace power ratings range widely:

Modern IGBT-based induction furnaces achieve specific energy consumption of approximately 550–650 kWh/tonne of liquid metal — a significant improvement over older thyristor-based systems. BEE (Bureau of Energy Efficiency) documented case studies confirm this range.

2. Post-Process Equipment — Significant Secondary Load

After melting and casting, the plant runs:

• Shake-out machines (vibrating equipment to remove sand from castings): 15–50 kW
• Shot blasting machines: 30–75 kW
• Grinding and finishing machines: 5–30 kW per machine
• Heat treatment furnaces (for alloy castings): 50–500 kW
• Sand plant (sand mixers, conveyors, reclamation): 30–100 kW

3. Utilities — Always-On Load

• Compressed air compressors: 30–200 kW (continuous during production)
• Cooling water pumps and cooling towers: 15–75 kW
• Lighting (factory shed, offices): 20–100 kW
• Pattern shop, machine shop (if integrated): 50–200 kW

Total Electricity Picture

A typical mid-size foundry producing 500–1,000 tonnes/month with two 1-tonne induction furnaces will have:

• Induction furnace peak draw: 1,000–1,400 kW during melting
• Other plant loads (compressors, post-process, utilities, offices): 200–500 kW (running continuously)
• Total connected load: 1.2–1.9 MW
• Monthly electricity consumption: 3–6 lakh units (depending on shifts and furnace utilisation)
• Monthly electricity bill at ₹8/unit (HT industrial): ₹24–48 lakh

Why Solar Is Valuable for Foundries (Even Though It Can't Power the Furnace)

A common misconception among foundry owners is: "Solar won't work for us — our induction furnaces consume too much power." This misses the point.

A 500 kW rooftop solar system cannot power a 1 MW induction furnace during melting. But it can power everything else in the plant simultaneously — and every unit generated by solar displaces a unit that would otherwise come from the grid at ₹7–10/unit.

Here's how the numbers look for a foundry:

The key insight: When the induction furnace is running, it draws from the grid. But the solar system's output simultaneously reduces the grid import for all other loads — effectively reducing the net units drawn from the grid. On a net metering arrangement, any solar surplus during non-melting periods (startup, breaks, cooling) is exported to the grid as a credit.

Over a month, a 500 kW rooftop solar system at a Delhi-NCR foundry can generate approximately 55,000–65,000 units (kWh). At ₹8/unit HT tariff avoided, this represents ₹4.4–5.2 lakh in monthly savings or approximately ₹52–62 lakh per year.

System Sizing for Foundry Solar

The right system size depends on your available rooftop area and your non-furnace electricity load:

Approach 1: Cover All Non-Furnace Loads

Size the solar system to match the "baseline load" — what the plant consumes when furnaces are off (compressors, lighting, offices, cooling, post-process equipment). This is typically 150–500 kW for a mid-size foundry. The solar system runs close to 100% self-consumption during furnace-off periods.

Approach 2: Maximize Rooftop Utilisation

For foundries with large sheds, install as much solar as the rooftop can accommodate — up to 500 kW to 1 MW or more. During furnace-off hours, excess solar is exported under net metering and earns grid credits. During furnace-on hours, solar offsets the non-furnace load while the furnace pulls from the grid. This maximises total unit generation and savings.

Rooftop Space Requirements

Foundry sheds are typically large, flat or slightly pitched — ideal for solar. As a guideline:

• 100 kW system: approximately 8,000–10,000 sq ft rooftop
• 300 kW system: approximately 24,000–30,000 sq ft
• 500 kW system: approximately 40,000–50,000 sq ft

Most mid-size foundries with a 5,000–10,000 sq metre factory floor easily have rooftop area for a 300–600 kW system.

Financial Returns: Sample Calculation

Foundry Profile:

• Location: Rajkot, Gujarat
• Production: 800 tonnes/month cast iron
• Induction furnaces: 2 × 1-tonne, 2 shifts
• Other loads: compressors, post-process, offices — approximately 300 kW continuous
• Monthly electricity bill: ₹35 lakh (at DGVCL HT tariff ~₹7.50/unit)
• Available rooftop: 40,000 sq ft (south-facing shed)

Solar System: 500 kW rooftop (TOPCon modules, ALMM compliant)

• Annual generation: approximately 7.5–8.5 lakh units (CUF ~17–19% in Gujarat)
• Annual savings: approximately ₹56–64 lakh (at ₹7.50/unit)
• System cost (CAPEX, 2026): approximately ₹1.8–2.1 Cr
• Payback (pre-depreciation): approximately 3.0–3.5 years
• With 40% accelerated depreciation (Year 1 tax benefit for profitable foundry): effective payback approximately 2–2.5 years
• IRR over 25 years: approximately 28–35%

Open Access Solar for Large Foundries

Foundries with monthly electricity consumption above approximately 2–3 lakh units and connected load above 1 MW can consider Open Access Solar — purchasing solar power from an off-site farm via the state grid. This is particularly relevant for foundries in Rajasthan, Gujarat, Karnataka, and Maharashtra where open access frameworks are well-established.

Open access solar delivers electricity at approximately ₹2.50–4.50/unit all-in (versus ₹7–10/unit from DISCOM), with savings of ₹3–6/unit on the procured quantum. For a 2 MW foundry consuming 10 lakh units/month, open access can save ₹30–60 lakh per month — transformational for unit economics.

State-specific notes:

• Gujarat (GERC): Banking charge of ₹1.50/kWh (valid until June 30, 2026); solar energy banked during daytime used at night for overnight/extended shift furnace operation
• Rajasthan (RERC): 8% banking charge; BESS-integrated open access projects get 75% wheeling exemption for 7 years
• Maharashtra (MERC): Well-established open access market; suitable for Pune and Kolhapur foundry clusters

For a complete explanation of open access: Open Access Solar India: Complete Guide for Industrial Buyers.

MSME Solar Financing Options for Foundries

Most Indian foundries are MSMEs. Several financing options make solar accessible without requiring large equity capital:

• SIDBI (Small Industries Development Bank of India): Green loan schemes for solar energy installations in MSMEs; interest rates approximately 8.5–10% per annum with long tenors (up to 7 years)
• IREDA (Indian Renewable Energy Development Agency): Term loans for renewable energy projects; offers competitive rates for MSME solar
• State-level MSME energy efficiency schemes: Several states (Gujarat, Maharashtra, Tamil Nadu) offer partial capital subsidies or concessional finance for MSME energy investments
• Commercial bank solar loans: SBI, Bank of Baroda, PNB, and private banks offer solar project financing at 9–11% per annum
• RESCO / OPEX model: Eliminates financing requirement entirely — zero capital outlay, savings from Day 1

For a full overview of solar financing: Solar Project Financing: SIDBI, IREDA, PFC/REC, and Bank Loans.

Energy Efficiency + Solar: A Combined Approach

For foundry owners, solar is most effective when combined with energy efficiency improvements in the melting process:

• IGBT-based induction furnaces instead of thyristor-based: saves 10–20% on melting energy (550 vs 680 kWh/tonne)
• Furnace lids and improved insulation: Reduces heat loss between melts
• Power factor correction (PFC) panels: Reduces reactive power penalties on electricity bills — often saves 3–8% of bill immediately at low cost
• Timed melt scheduling: Clustering melt cycles to avoid ToD peak surcharges

Combining energy efficiency measures with rooftop solar can reduce a foundry's electricity bill by 30–50% — a transformative improvement for cost-competitive casting operations.

For industrial energy management context, also see: Solar Battery Storage for Industry in India.

Choosing an EPC Partner for Foundry Solar

Foundry rooftops present specific EPC challenges:

• Roof structural loads: Foundry sheds often have older RCC or pre-engineered building (PEB) structures; structural load assessment is critical before placing solar panels
• Dust and particulate matter: Metal dust, slag, and foundry emissions can coat solar panels; more frequent cleaning schedules (monthly rather than quarterly) may be needed
• High ambient temperatures: Foundry environments near furnaces can raise ambient temperatures, affecting solar panel efficiency slightly — factor this into yield projections
• Three-phase power quality: Induction furnaces introduce harmonics into the electrical system; ensure the solar inverter specification includes harmonic tolerance

Sun Wave Technologies has experience designing and installing solar systems on industrial factory rooftops including heavy manufacturing environments. We conduct detailed structural and electrical assessments before system design, and specify equipment suited to the operating environment.

For guidance on selecting an EPC partner: How to Choose a Solar EPC Company in India.

Frequently Asked Questions

Q: Can solar directly power an induction furnace during melting? Only partially. A single 1-tonne induction furnace draws 500–700 kW; a 500 kW rooftop solar system cannot alone power the furnace. However, the solar output simultaneously offsets grid import for all other plant loads — reducing total net units drawn from the grid. For very small furnaces (below 200 kW), a large solar system could theoretically cover a significant portion of furnace load on a net basis.

Q: Our foundry runs night shifts — is solar still useful? Yes. Even for foundries with significant night shift operations, daytime solar generation offsets day shift consumption. Net metering arrangements allow solar surplus to be credited and applied against night consumption. For foundries in states with time-of-day (ToD) tariff structures, daytime solar consumption during the lower-tariff period and grid consumption at night are both accounted for — the net financial benefit depends on your state's ToD tariff schedule.

Q: Is solar suitable for an aluminium die-casting plant versus a grey iron sand casting plant? Both are suitable, but with different energy profiles. Aluminium die-casting typically uses smaller, higher-frequency furnaces with quicker cycle times; grey iron sand casting uses larger coreless induction furnaces. The non-furnace loads (die casting machines, trimming presses, pressure die casting equipment vs. shakeout machines, grinding lines) differ in composition but are broadly similar in total demand. Solar covers the non-furnace load in both cases.

Q: Our foundry is in a MIDC or industrial estate — can we install rooftop solar? Yes, provided your MIDC or industrial estate allotment agreement permits rooftop structures. Most industrial estate allotments allow rooftop solar installations as these are considered plant and machinery. Confirm with your estate officer and obtain a structural NOC from a licensed structural engineer before installation.

Q: What is the lifespan of a solar system on a foundry rooftop, given dust and heat? Solar panels are rated for 25 years of operation under standard conditions. In a foundry environment with higher dust and particulate levels, regular cleaning (monthly rather than quarterly) and the use of tempered glass panels with anti-soiling coatings helps maintain performance. Choose an EPC contractor who includes an Operation and Maintenance (O&M) contract with defined cleaning schedules.

Q: Do we need permission from our electricity board (DISCOM) before installing solar? Yes. For grid-tied solar systems with net metering, you must apply to your DISCOM for a net metering connection approval before commissioning. Your EPC contractor typically handles this process. The timeline varies by state (4–12 weeks typically). Work with an experienced EPC partner familiar with your state DISCOM's process.

Q: Can foundry operators earn Renewable Energy Certificates (RECs) from their solar plant? Yes — foundries with captive solar plants that consume power internally can register on the NLDC REC Registry and earn RECs (1 REC per 1 MWh generated and consumed). RECs can be sold monthly on IEX or PXIL for additional revenue. See our guide: Solar RECs: How Indian Factories Trade Green Certificates.

Sources

• IOP Science — A Review of Energy Consumption in Foundry Industry: iopscience.iop.org
• Carbon Minus — When Foundry Induction Furnace Upgrades Pay for Themselves: carbonminus.com
• Clessotechnocast — Green Initiatives by Investment Casting Foundries in India: clessotechnocast.com
• Bureau of Energy Efficiency (BEE) — Induction Furnace Energy Benchmarks (IGBT: 550–650 kWh/tonne)
• Mercom India Q1 2026 India Solar Open Access Market Report