Methodology
Spec sheets, filings and the vendor’s own releases first. One source per number, a date on every row, last checked 11 Nov 2026.
Where the data comes from
We read each provider’s product pages and datasheets, its press releases and investor filings, and certification statements such as UL 9540A results. Where a provider publishes no figure of its own, we take it from named trade press (Energy-Storage.news, ESS News, pv magazine, Utility Dive) and say so in the row’s sources. Every record lists its sources with the date we read them, and every number in the table links to the source behind it.
Who is in the table
A provider is listed when it sells battery or long-duration storage systems, or the cells inside them, and at least three of its data fields (energy per unit, deployed GWh, cycle life, warranty, certifications, data center offer, products) can be sourced. Providers that publish more get added. The shortlists cut the table by buyer question: data center storage, long duration, cell makers, integrators and UL 9540A.
Supplier type and capacity
Supplier type is our classification of each provider’s sourced portfolio: integrator, cell maker, power major, long-duration technology or controls. Headquarters appear only where the company states them. Deployed GWh counts shipped or installed storage; plans, letters of intent and supported fleets stay in the notes. Providers that closed or sold their storage business leave the table, and their fleets point to the new owner.
How to read the numbers
Energy per unit is the vendor’s stated MWh for one flagship unit, usually a 20-ft container; some vendors quote nameplate and some usable energy, and the spec notes say which. Deployed is the cumulative GWh the vendor reports, which may be shipments or installed capacity. Deployed + contracted adds backlog or contracted projects. Cycle life is the vendor’s rated figure at its own test conditions, so a cell rating and a system rating are not directly comparable. UL 9540A is flagged when the vendor states a test or publishes the result; the level of the test (cell, module, unit) is in the spec notes.
How we verify
Each row shows the date we last checked it. A field is filled only when a source states it; when we cannot verify a figure, the cell stays empty. We never estimate.
Corrections
Providers and readers can send corrections to hello@bessproviders.com with a public source. We update the row and its verified date. Featured placement is paid and labelled; it never changes a row’s data or its position in the sorted table.
Reuse
The dataset is free to reuse under CC BY 4.0 with a link to bessproviders.com. Download it as CSV or JSON.
Field definitions
20 fields- Type
- Editorial supply-chain classification based on the sourced portfolio: system integrator, cell manufacturer, non-lithium or mechanical storage developer, power equipment group, or software and controls supplier.
- Chemistry
- Main storage chemistry of the flagship product. LFP is lithium iron phosphate; NMC is lithium nickel manganese cobalt oxide; LTO is lithium titanate. Mechanical covers gravity, compressed air and CO2 stores. Mixed means the vendor sells more than one chemistry at scale.
- Flagship product
- The vendor's main grid-scale or commercial storage product line, as the vendor names it.
- Energy per unit MWh
- Energy of one flagship unit (usually a 20-ft container or one enclosure), as the vendor publishes it. Rating basis (usable or nameplate, beginning of life) is in the spec notes.
- Duration
- Discharge durations the vendor offers at rated power, in hours, as published (for example 2-4 h, or 100 h).
- Deployed GWh
- Cumulative storage the vendor says it has deployed, delivered or shipped, in GWh, at the date of the cited source. Shipments and installed capacity differ; the spec notes say which one the vendor reports.
- Deployed + contracted GWh
- Deployed plus contracted or awarded storage (backlog under contract) in GWh, as the vendor states it. Blank when the vendor publishes no contracted figure.
- Cycle life cycles
- Rated cycle life of the flagship cell or system as the vendor publishes it. Test conditions (temperature, depth of discharge, end-of-life capacity) differ by vendor and are in the spec notes.
- Warranty years
- Longest standard product or performance warranty term the vendor publishes for the flagship system, in years.
- UL 9540
- The vendor states a named system in this record is certified or listed to UL 9540. The spec notes identify any earlier product or model-specific scope.
- UL 9540A
- A cited manufacturer statement or published report describes UL 9540A testing for a named system or cell in the record. Read the spec notes for the model and test level; this is not a blanket certification of all products.
- Data center offer
- The vendor markets a storage product, reference or program for data centers: backup, UPS, grid-interactive UPS, load smoothing for AI training, or bridging power while a grid connection is built.
- Data center notes
- What the data center offer is, with named products, customers or projects where the vendor publishes them.
- Parent
- Owner or parent group when the provider is a subsidiary or joint venture.
- Products
- Named storage products and cells, with sizes where published.
- Spec notes
- Rating conditions, test basis and dated context for the numbers in the row.
- Market status
- Dated ownership, deal or operating context: joint ventures, acquisitions and manufacturing agreements.
- Services
- Published integration, controls or lifecycle services offered by the provider.
- Reference project
- A named project and its reported status and capacity. Project capacity is not a product unit rating.
- Headquarters
- Headquarters city and country only when an explicit cited company statement supports the location.