Make vs Buy Decisions in BESS Manufacturing

The battery energy storage system (BESS) industry is at an inflection point in India. With over 47 GWh of BESS capacity expected to be deployed by 2030 under the National Energy Storage Mission and the market projected to grow from approximately $2.05 billion in 2026 to $8.59 billion by 2031 at a CAGR of 33.2%, manufacturers and developers face one of the most consequential choices in their business strategy: what to make in-house, and what to buy.

This is not a one-time procurement decision. It is a recurring strategic exercise that determines competitive positioning, margin capture, supply chain resilience, and long-term technical capability. For the Indian BESS industry — still nascent in domestic cell manufacturing but rapidly scaling in assembly, integration, and deployment — the make vs. buy question touches every level of the value chain, from raw cells to containerized systems.

The BESS Value Chain: Understanding What You Are Deciding About

Before applying any decision framework, it is essential to map out what exactly is being evaluated. A BESS is not a single product — it is a layered system assembled from multiple sub-components, each of which can be independently made or bought.

The full value chain, from upstream to deployed system, consists of:

1. Raw materials and chemical processing — lithium, cobalt, nickel, graphite, electrolyte, separator
2. Cell manufacturing — electrode production, cell assembly, cell finishing; requires cleanrooms and gigafactory-scale capex
3. Module and pack assembly — cell sorting, busbar welding, BMS harness integration, thermal management
4. Container integration — rack installation, HV interconnects, EMS/BMS wiring, HVAC integration, FAT
5. Power Conversion System (PCS) and Energy Management System (EMS) — power electronics, control software, grid interface
6. Project development and O&M — EPC, commissioning, 12–25 years of operations

The margins across these layers are not uniform. Industry analysis indicates best margins of 15–25% in module/pack assembly and container integration (steps 3–4), while cell manufacturing offers 20–30% margins but demands massive capex. Project development yields 10–15% and maintenance 8–12%. This margin distribution has profound implications for where to place manufacturing bets.

The Strategic Framework: Five Questions Before Deciding

The make vs. buy decision is not resolved by a single metric. It is a structured decision tree that sequentially evaluates five dimensions:

1. Is It a Core Competency?

If the activity directly underpins competitive differentiation — quality traceability, system integration depth, proprietary BMS algorithms, thermal management design — it should be made in-house. Outsourcing core competencies hollows out the technical foundation of the business. For a BESS manufacturer aiming to win long-term O&M contracts or build bankable products, cell-level quality control is a core competency. For an EPC contractor deploying third-party systems, it is not.

2. Is a Reliable External Supplier Available?

In the Indian BESS landscape, reliable suppliers exist across a spectrum. For cells, CATL, EVE, and REPT from China dominate supply, with domestic Indian cell supply functionally near zero as of mid-2026. For BMS and EMS software, some localization is possible, but high-precision electronic components remain primarily imported. For container fabrication, Indian vendors are available and competitive. Supplier reliability therefore varies sharply by component — making blanket outsourcing strategies dangerous.

3. Is Demand Volume High and Stable Enough to Justify Fixed Costs?

Economies of scale matter enormously in manufacturing. For a dedicated semi-automated BESS pack line, approximately 50 MWh per year is the practical minimum floor to justify the investment. A fully automated line capable of 500+ MWh annually requires Rs. 40–80 crore in capital expenditure. Making sense of in-house production at these scales requires either a secured order pipeline or a credible 3-year demand projection. Below these thresholds, buying from established suppliers is almost always the capital-efficient path.

4. Can the Supplier Deliver Consistent Quality?

Quality in BESS is not cosmetic — it determines safety, degradation curves, and warranty costs over a 15–20 year system life. An assembler importing pre-built modules from China has no visibility into the cell matching, weld quality, or internal resistance distribution inside those modules. When a field fault occurs, root-cause analysis requires cell-level data that only the original manufacturer holds. Manufacturers operating a cell-to-container line can trace every cell to its intake inspection record, sort lot, and formation cycle data — a capability that translates directly into warranty cost control and customer confidence.

5. Are IP or Proprietary Processes at Stake?

BMS algorithms that predict thermal runaway, SOC estimation models calibrated to specific cell chemistries, and EMS control logic that enables value-stacking across multiple revenue streams represent genuine intellectual property. Outsourcing these functions to a third party — particularly one from a geopolitically sensitive jurisdiction — exposes this IP to leakage. The U.S. experience of having 90% of inverters sourced from Chinese manufacturers is now considered a national security risk; India’s Ministry of Power is actively considering mandatory localization requirements precisely for this reason.

Total Cost of Ownership: Why Purchase Price Is the Wrong Metric

The most persistent mistake in make vs. buy analysis is comparing the in-house production cost against the supplier’s quoted price. The correct comparison is Total Cost of Ownership (TCO):

TCO= Purchase Price + Logistics + Quality Cost +Lead-Time Buffer + Risk Premium + Coordination Cost

In the BESS context, these hidden costs are significant:

• Component cost advantage: Cells represent approximately 45–55% of total BESS system cost. A manufacturer buying raw cells directly eliminates the module manufacturer’s margin — a differential of approximately ₹8–12 lakh per MWh at current prices.
• FAT rework cost: An assembler importing pre-built modules typically sees 3–8% Factory Acceptance Test rework rates. Each rework event costs 3–6 person-days of engineering time and delays shipment by 1–3 weeks. At scale, this compounds into millions in annual cost.
• Warranty risk: Root-cause analysis on field failures is faster and cheaper when the manufacturer controls cell-level data. An assembler must escalate warranty claims to an overseas module supplier — slow, costly, and damaging to customer relationships.
• Currency and geopolitical risk: India’s battery import bill has climbed to over USD 3 billion annually as of FY2025. Each rupee depreciation against the yuan inflates costs for businesses fully dependent on imported assembled systems. In-house manufacturing with imported cells (at reduced duty under the 5% cell import structure) partially hedges this exposure.

Applying the Framework Across BESS Value Chain Layers

Not all components warrant the same make vs. buy decision. The framework produces different answers at different layers:

The Cell-to-Container Argument: When Vertical Integration Pays

The debate between cell-to-container integration and module-import assembly crystallizes the make vs. buy choice at its most impactful level.

A fully integrated cell-to-container operation performs cell incoming inspection, grading, module assembly, busbar welding, pack integration, thermal management installation, BMS commissioning, and FAT as a single production chain. The advantages compound:

• Quality traceability: Every cell in every container is traceable to its intake test, capacity grade, and sort lot. First-pass FAT yield on a well-run integrated line reaches 99.7%, compared to the 3–8% rework typical of assembly operations.
• Cost economics: Eliminating the module manufacturer’s margin recovers ₹8–12 lakh per MWh. Across a 100 MWh annual deployment, this is ₹8–12 crore in recaptured margin.
• Degradation consistency: Cells matched to within ±0.5% capacity in the same module degrade uniformly, meaning the system delivers on its warranted life curve rather than degrading early due to cell mismatch.
• Warranty defensibility: When a customer raises a warranty claim, the cell-to-container manufacturer has the data to diagnose, defend, or resolve it. The assembler has a supply chain dispute with an overseas vendor.

However, cell-to-container manufacturing also demands proportionate commitment. A genuine integrated line requires:

• Rs. 40–80 crore capex for a 500+ MWh per year fully automated line
• 12–18 months from contract signing to commercial production
• Skills in cell handling, laser welding, formation cycling, and MES integration that are scarce outside manufacturing clusters in Pune, Chennai, Bengaluru, and Manesar
• ISO 7 or ISO 8 cleanroom conditions, ESD flooring, and HVAC designed for Indian ambient conditions of 35–45°C and 70–90% relative humidity

For organizations below the scale threshold, or early in their BESS market development, the rational path is to buy finished packs or modules from established suppliers while building market presence — and to revisit vertical integration once volumes justify the commitment.

India-Specific Dynamics That Reshape the Calculus

The make vs. buy decision for BESS in India is conditioned by a policy and market environment that differs meaningfully from other geographies.

PLI Scheme and Domestic Value Addition

The ₹18,100 crore National Programme on ACC Battery Storage incentivizes 50 GWh of domestic cell manufacturing capacity, with 10 GWh earmarked for grid-scale stationary storage. The scheme’s localization ladder requires domestic value addition of at least 25% within two years, rising to 60% within five years. However, as of early 2026, only 1.4 GWh (2.8% of the 50 GWh target) had been commissioned, meaning near-term projects cannot bank on domestic cell supply. The honest conclusion: PLI is a medium-term tailwind for domestic cell costs, not an immediate procurement option.

Customs Duty Structure

Budget 2026–27 extended customs duty exemptions on capital goods used for lithium-ion cell and BESS manufacturing. This directly lowers capex for in-house manufacturing facilities — a meaningful argument for the “make” case for organizations at sufficient scale. Simultaneously, importing assembled containers from China attracts higher cumulative duties, while importing cells for local assembly attracts lower duty, creating a policy-reinforced incentive for the import-cells-and-assemble-in-India model.

Make in India and DPIIT Compliance

SECI tenders and DISCOM procurement increasingly require domestic manufacturing under Atmanirbhar Bharat and Make in India frameworks. DPIIT domestic content requirements, when enforced, will be production-value based — meaning meaningful domestic value addition must occur in India, not just final assembly of imported modules. This regulatory trajectory increasingly penalizes the pure import-and-assemble model and rewards genuine in-country manufacturing.

Geopolitical Supply Chain Risk

The BESS supply chain’s heavy concentration in China — from cells to inverters to PCS — is explicitly identified as a national security and supply chain vulnerability by energy security analysts. India is actively considering mandatory localization requirements for BESS systems to reduce this dependency. Organizations that build domestic manufacturing capability now position themselves ahead of a regulatory shift that appears increasingly likely.

BESS Cost Decline Rate

Per-kWh BESS costs discovered through competitive bidding fell from ₹10.18/kWh in 2022–23 to approximately ₹2.1/kWh in late 2025. This rapid cost decline affects the make vs. buy calculus in two ways: it compresses the window in which today’s capex decision yields competitive-cost product before the market reprices, and it makes the margin-recapture argument for in-house integration stronger, because margins on finished systems are tightening while the value of production efficiency compounds.

Common Strategic Mistakes in BESS Make vs. Buy Decisions

• Treating buy as automatically cheaper because the supplier quote is lower: This classic error ignores TCO components — FAT rework, warranty risk, logistics buffer stock, and currency exposure — that often erase the apparent savings.
• Vertical integration at insufficient scale: Investing in in-house module assembly without a credible path to 50+ MWh annual throughput creates fixed cost dilution that makes in-house production more expensive than buying. Scale threshold is not a suggestion — it is a financial boundary.
• Outsourcing BMS firmware and EMS logic: The intelligence layer of a BESS system is its most defensible IP. Companies that license or outsource their BMS and EMS stack are building products that are replicated by the next vendor to use the same supplier.
• Assuming domestic cell supply is available: The PLI scheme’s ambition is real, but commissioning timelines have consistently slipped. Project economics built on domestically sourced cells at competitive prices need to carry a sensitivity assumption for imported cells.
• Piecemeal line assembly instead of turnkey integration: Sourcing individual machines from multiple vendors and self-integrating a BESS production line distributes accountability across vendors who each point at others when failures occur. A turnkey line with single-contract OEE and quality guarantees is typically worth the premium.

A Decision Framework in Practice: Three Archetypes

Archetype 1: The EPC Contractor Entering Storage

Situation: 10–30 MWh annual deployment, no manufacturing footprint, primary business is project execution.

Recommended posture: Buy finished systems from domestic manufacturers or import under temporary duty exemptions. Develop EMS integration and O&M capability in-house. Revisit when annual storage deployment exceeds 50 MWh.

Archetype 2: The Mid-Scale Integrator (50–200 MWh/yr)

Situation: Growing order pipeline, current module-import assembly operation, PLI scheme interest.

Recommended posture: Invest in module and pack assembly (steps 3–4 of the value chain). Buy cells directly rather than pre-built modules. Build BMS firmware capability. Outsource PCS, HVAC, and container fabrication. This is the margin-capture sweet spot — the layer with 15–25% margins, achievable without gigafactory capex.

Archetype 3: The Vertically Integrated Manufacturer (500+ MWh/yr)

Situation: Committed manufacturing strategy, PLI eligibility, long-term supply agreements with developers.

Recommended posture: Cell-to-container integration with full automated line. Own cell quality data, module assembly, and FAT. Develop in-house EMS capability for value-stacking and grid services. Source cells, PCS, and specialist components externally while controlling everything that defines system performance and warranty.

Conclusion: Make vs. Buy Is a Living Decision

The make vs. buy decision in BESS manufacturing is not a one-time call made at company founding. It is a living strategic exercise that must be revisited as volumes scale, technology matures, the regulatory environment evolves, and the competitive landscape shifts.

India’s BESS sector in 2026 presents a clear directional logic: buy cells (domestic supply is not ready), make modules and packs (this is where margin lives and where quality accountability matters), make or tightly license EMS/BMS intelligence (this is defensible IP), and buy the commodities (PCS, HVAC, fabrication) that established suppliers produce more efficiently.

The companies that get this layering right will not only capture better margins today — they will build the manufacturing muscle, quality systems, and IP moat that sustains competitive advantage as India’s storage market scales toward its 47 GW / 411 GWh target by 2032.