Cell suppliers sell the battery cells. System integrators combine those cells with power electronics, controls, cooling, and fire protection into a finished system. BESS suppliers split into two groups that solve different problems.
Getting the supplier right matters because storage is now the fastest-growing power technology. According to McKinsey, the global installed capacity of battery energy storage systems (BESS) exceeded 300 GWh by 2025, with an annual growth rate of approximately 50% between 2022 and 2030. Many buyers contact the wrong type first, which causes delays, financing gaps, and permitting problems. This guide ranks the top cell suppliers and top system integrators separately, then shows how to match each to your project. If the technology is new to you, start with what a battery energy storage system is.
Quick Answer: Which Supplier Do You Need?
| You are… | You need | Start with |
|---|---|---|
| An integrator, pack builder, or specifying a chemistry | A cell supplier | CATL, HiTHIUM, EVE Energy, CALB, BYD |
| A developer, EPC, or commercial buyer wanting a complete system | A system integrator | BYD, Tesla, Sungrow, CRRC Zhuzhou, CATL |
What this means: if you do not assemble battery systems yourself, you want an integrator, not a raw cell maker.
Cell Supplier vs System Integrator
A cell is the basic battery unit. A cell supplier manufactures cells in volume and sells them to integrators. An integrator buys cells, then adds the power conversion system (PCS), battery management system (BMS), energy management system (EMS), and other supporting systems. Some companies do both. BYD and CATL make cells and also build systems, so each appears in both rankings below, described by the relevant business.
How We Ranked These Suppliers
We rank suppliers by 2025 global BESS shipment volume, not revenue, project pipeline, manufacturing capacity, or installed project ownership. Market-share data come from Benchmark Mineral Intelligence’s 2025 BESS shipment data. Where Benchmark ranks a company in both cells and systems, that company appears in both tables, described by each business line. BYD and CATL appear twice for this reason. The shipment data sets the order; we do not move or drop companies by preference.
Top BESS System Integrators
| Podjetje | 2025 System Share | Note |
|---|---|---|
| BYD | 13% | Also a top cell supplier |
| Tesla | 10% | Only Western firm in the top three |
| Sungrow | 9% | Strong in solar plus storage |
| CRRC Zhuzhou | 6% | State-backed, China-focused |
| CATL | 6% | Also the largest cell supplier |
BYD
Market position:No.1 global BESS system integrator in 2025, with about 13% market share and more than 60 GWh shipped.
Core strength:BYD controls both cells and systems. It makes its own Blade LFP cells and integrates them into complete systems such as the MC Cube.
Best for:Large utility-scale and international projects that need proven delivery scale and one supplier for both cells and complete systems.
Buyer consideration:BYD is strong in scale, but buyers still need to verify local service, certification support, warranty terms, and grid-connection experience in the target market.
Tesla
Market position:No.2 global BESS system integrator in 2025, with about 10% market share and 46.7 GWh deployed.
Core strength:Tesla combines Megapack hardware with software for monitoring, dispatch, control, and market participation.
Best for:Residential or large-scale projects that need bankability, standardized design, mature software.
Buyer consideration:Tesla is less suitable for buyers that need highly customized system design. Buyers should also check lead time, local service capacity, domestic-content fit, and grid-code support.
Sungrow
Market position:No.3 global BESS system integrator in 2025, with about 9% market share.
Core strength:Sungrow’s advantage comes from PV inverters, PCS, and grid-integration experience. Its PowerTitan systems are built for projects where batteries, PCS, EMS, and grid control must work together.
Best for:Solar-plus-storage projects, grid-tied storage, and commercial or utility sites where power-electronics quality is critical.
Buyer consideration:Sungrow projects may involve different equipment scopes, so buyers need to confirm PCS scope, EMS responsibility, commissioning support, and after-sales coverage before signing.
CRRC Zhuzhou
Market position:Tied near 6% of 2025 global BESS system shipments.
Core strength:CRRC Zhuzhou brings state-backed industrial strength, high-power electronics experience, and grid-equipment capability from CRRC’s railway traction background.
Best for:Large domestic Chinese grid-scale storage projects that benefit from state-owned industrial backing and grid-side project experience.
Buyer consideration:Its international footprint is smaller than BYD, Tesla, and Sungrow. Buyers outside China should verify overseas references, certification support, local service, and compliance capability.
CATL
Market position:Tied near 6% of 2025 system shipments as an integrator, but better known as the world’s largest BESS cell supplier.
Core strength:CATL’s advantage is cell technology, manufacturing scale, and bankability. Its complete systems, including the Tener line, benefit from trust in CATL’s battery cells.
Best for:Projects that prioritize CATL cell bankability and may want either CATL cells or a CATL-based complete system.
Buyer consideration:CATL’s role must be clarified early. Buyers need to know whether they are buying cells only or a full CATL-integrated system. If buying a full system, confirm PCS, EMS, certification, service, and warranty responsibility.
Top BESS Cell Suppliers
| Podjetje | 2025 Cell Share | Note |
|---|---|---|
| CATL | 20% | Also a top-tier system integrator |
| HiTHIUM | ~12% | Storage-only specialist |
| EVE Energy | ~12% | Very large-format cells |
| CALB | Not disclosed | Strong in utility-scale |
| BYD | Not disclosed | Also the largest system integrator |
CATL
Position:Largest BESS cell supplier, with about 20% of global cell shipments. Its share fell from 29% in 2024 and 32% in 2023 as competitors gained ground.
Why it stands out:Manufacturing scale, broad customer adoption, strong bankability, and high acceptance among developers, lenders, and integrators.
Best fit:High-volume utility and commercial storage projects that need a financeable, widely accepted cell supplier.
Weak point:Market share is falling, and CATL may not be the most flexible or lowest-cost option. Buyers should clarify whether they are buying cells only or a full CATL-integrated system.
HiTHIUM
Position:Second-largest BESS cell supplier, with roughly 12% of global shipments, up from fourth place and about 9% in 2024.
Why it stands out:Dedicated focus on stationary energy storage. Product development is shaped around long cycle life, large-format cells, and grid or commercial storage needs.
Best fit:Grid-scale and commercial BESS projects that prioritize storage-specific cell design.
Weak point:Shorter global track record than CATL. Buyers should verify bankability, international references, certification data, and local service support.
EVE Energy
Position:Third-largest BESS cell supplier, with around 12% of global shipments. It slipped from second place in 2024 but remains highly competitive.
Why it stands out:Very large-format LFP cells, including its 628 Ah cell, help integrators improve energy density and reduce container count, land use, and balance-of-system cost.
Best fit:High-capacity utility and commercial projects where energy density and container efficiency matter.
Weak point:Large-format cells place higher demands on system design. Buyers should confirm BMS compatibility, thermal management, safety testing, and the integrator’s experience with EVE cells.
CALB
Position:Top-five BESS cell supplier in 2025.
Why it stands out:High-capacity LFP cells for large storage projects, with strong momentum as market-share gaps among leading suppliers narrow.
Best fit:Large grid-scale projects that need competitive, high-volume LFP cell supply.
Weak point:Less disclosed market-share detail and lower global visibility than CATL, HiTHIUM, and EVE. Buyers should confirm certification data, supply security, international references, and sourcing requirements.
BYD
Position:Top-five BESS cell supplier and the largest BESS system integrator.
Why it stands out:Blade LFP technology and a cell-to-system supply model. Buyers can source cells and complete systems from the same group.
Best fit:Buyers that want Blade LFP technology and may prefer a vertically integrated supplier for both cells and complete BESS systems.
Weak point:Often stronger as a system integrator than as a standalone cell supplier. Buyers should clarify cell-only availability, technical specifications, warranty boundaries, and full-system responsibility.
Why the Integrator Choice Matters Most for Commercial Buyers
For commercial and industrial buyers, choosing a BESS supplier is not only about picking the largest global brand. The real value comes from whether the supplier can take responsibility for the full system, from sizing and configuration to certification, commissioning, service, and warranty. This is where a system integrator becomes essential. Instead of buying cells, inverters, controls, cooling, and fire protection separately, buyers get one complete system with clearer responsibility and fewer interface risks.
ESYsunhome works in this integrator role for both Residential and C&I storage projects. It combines solar, storage, diesel generator, and EV charging functions with smart, predictive energy management, designed for sites that need microgrid support or reliable power under weak-grid conditions. For peak shaving, backup, or microgrid use, these turn the comparison above into a deployable, supported system.
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Reference
- Benchmark Mineral Intelligence, Top Energy Storage Cell Suppliers and System Integrators in 2025: source.benchmarkminerals.com
- Benchmark Mineral Intelligence, BESS data and market overview: source.benchmarkminerals.com
- Electrek, BYD surpasses Tesla as top energy storage deployer (Benchmark 2025 data): electrek.co
- International Energy Agency, Global Energy Review 2026, Battery Storage: iea.org
- UL Solutions, UL 9540A Test Method: ul.com