The Energy Storage Contract Alliance (ESCA), a non-profit association based in Lausanne, Switzerland, has launched what it calls the first open contract standard for utility-scale battery energy storage system (BESS) procurement.
The alliance launched Oct. 13 with 22 members, including utilities, independent power producers, developers and asset owners, which have a combined BESS portfolio of more than 40 GWh. Its steering committee includes BW ESS, Fortum, MN8 Energy, Munich Re, Neoen and Sinovoltaics, and members include Goldbeck Solar, ILOS, Pacifico Energy and Eiffage.
“Every BESS project works through the same technical and contractual questions, and most of the answers are not project-specific,” said Arthur Claire, secretary general of ESCA. “ESCA puts a complete baseline in the open, so any developer, utility or manufacturer can take it, use the parts that fit and ignore the rest.”
Buyer terms
The ESCA Model BESS Supply and Purchase Agreement, now at version 1.2, is written from the buyer’s side and sets no prices. Its core clauses can be read and downloaded free without registration, while members get the full contract and more than 15 technical appendices, including testing and warranty schedules. Use is voluntary, and any clause can be changed.
Suppliers must provide origin data for cells and components within 14 days of the start of each manufacturing batch, report cybersecurity incidents within 24 hours and comply with the European Union’s NIS2 directive and the IEC 62443 standard.
Every container must be inspected before shipment, with no sampling, and no system may ship without a pass certificate from the buyer’s third-party inspector. Late delivery incurs liquidated damages of 0.2% per day from the 16th day after the scheduled delivery period.
Availability is measured at the system level, including the power conversion system, energy management system and HVAC. Usable capacity must be at least 80% at the end of the warranty. Serial defects are presumed to affect every unit sharing a design or production batch unless the supplier proves otherwise. Disputes go to International Chamber of Commerce arbitration seated in Switzerland or Singapore.
“Utility-scale energy storage is scaling faster than the contracts that underpin it,” said Pedro Garcia Hrdy, senior vice president and head of technical operations at MN8 Energy.
Cost pressure
ESCA cited InfoLink Consulting figures showing global BESS shipments rose about 75% to around 420 GWh in 2025, with about 600 GWh expected this year. The alliance said a common reference should cut drafting time and costs, make bids easier to compare and help smaller developers negotiate on equal terms.
“As the energy storage sector is witnessing increasingly large procurement processes that often focus on the lowest possible costs, this race-to-the-bottom approach may undercut vital contractual and procurement-related practices and threaten the viability of a BESS project,” said Naim El Chami, battery technical expert at Neoen.
Sinovoltaics, a quality assurance firm that provides supplier audits, factory inspections and acceptance testing for BESS projects, serves as ESCA’s technical secretariat and drafted the first version of the contract. The steering committee will decide on future revisions.
Industry participants at a pv magazine Focus panel in Munich in June said quality control and contract design, rather than battery chemistry alone, determine whether BESS projects stay bankable. They noted that factory audits regularly uncover quality issues, even at tier-one suppliers, and that liquidated damages and insurance terms decide who bears the cost of delays.
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