IN Brief:
- YEO Teknoloji has signed a $58.6 million EPC-F contract to deliver a 250MWh BESS for Azerbaijan's grid operator AzerEnerji.
- Scope includes batteries, PCS, BMS, EMS, high-voltage substation works, grid integration, installation, and commissioning.
- The system is scheduled for commissioning within one year, with batteries supplied by YEO group company REAP Battery.
YEO Teknoloji has signed a $58.6 million contract with Azerbaijan’s grid operator AzerEnerji for the turnkey delivery and financing of a 250MWh battery energy storage system, extending a storage programme that has already brought 500MWh of capacity into service.
The project will be delivered under an EPC-F model covering engineering, procurement, construction, and financing. YEO’s scope includes the battery system, power conversion equipment, battery management system, energy management system, installation, commissioning, a high-voltage substation, and integration with the electricity network.
Construction is expected to begin quickly, with the complete system scheduled to enter operation within one year. Financing will be provided through local banks with a four-year repayment period, linking the technical delivery programme directly with the mechanism used to fund it.
No power rating has been disclosed for the new system, so its discharge duration cannot yet be calculated from the announced 250MWh energy capacity. That missing figure is important because a 250MWh battery configured at 50MW would perform a different system role from the same energy capacity connected through 125MW or 250MW of power conversion equipment.
The disclosed scope nevertheless shows that the contract extends well beyond container supply. Power conversion equipment will control transfers between the DC battery system and the AC network, while the battery management system will monitor cells and modules and enforce operating limits. The energy management system will coordinate dispatch according to the operational requirements set for the plant.
High-voltage substation work adds another major engineering package. A grid-scale battery only becomes useful to the electricity system when its output can be transformed, switched, protected, measured, and synchronised at the voltage required by the network. Transformers, switchgear, protection, metering, auxiliary systems, and communications therefore sit between battery containers and the wider grid.
YEO says the batteries will be manufactured by group company REAP Battery. That gives the contractor a vertically integrated element within the project, combining battery supply with system engineering, grid integration, construction, and financing rather than relying entirely on unrelated suppliers for the principal package.
The latest contract follows two battery systems with a combined capacity of 500MWh that were contracted in 2025 and commissioned during the second quarter of 2026. The additional 250MWh therefore takes the amount delivered or contracted under the YEO-AzerEnerji programme to 750MWh, although the projects may have different power ratings and operating roles.
Azerbaijan is expanding renewable generation and reinforcing its electricity system, increasing the need for controllable capacity that can respond when generation and demand diverge. Storage can shift energy between periods, provide rapid changes in power, and support system operation, but the precise services available depend on connection design, controls, and dispatch arrangements.
The operating role of the new battery has not yet been specified publicly. Without an announced MW rating, grid-code configuration, or service requirement, it would be premature to describe the installation as a defined frequency response, reserve, congestion management, or renewable shifting asset.
Its eventual function will depend on the technical parameters set during engineering and on AzerEnerji’s operating strategy. Power rating, usable energy, state of charge limits, conversion efficiency, reserve margins, cycle policy, and network location will all influence which services can be delivered and for how long.
The EPC-F model is notable because financing can be as important to storage delivery as hardware. Battery projects require substantial upfront spending while their system value or revenues accrue over several years. Combining funding with engineering and construction can allow a customer to contract one delivery structure rather than arranging the technical and financial packages separately.
That approach also couples the schedules. Procurement, lender conditions, construction progress, milestone payments, commissioning, and repayment arrangements have to remain aligned. A delay in substation equipment or grid works can affect project cash flow even if battery modules are available on time.
The one-year commissioning target will require several workstreams to progress in parallel. Detailed engineering must establish the battery and power conversion configuration, civil works have to prepare the site, substation equipment must be procured and installed, controls and communications have to be integrated, and the complete plant then needs electrical and functional testing.
Grid integration will be particularly important during commissioning. A battery capable of changing its output rapidly can affect voltage, frequency response, harmonics, fault behaviour, and protection coordination. Control settings must respect network limits while preserving the flexibility for which the plant is being installed.
The contract also creates another outlet for REAP Battery manufacturing. Bringing system production within YEO’s wider group can tighten interfaces between battery hardware, software, and EPC delivery, although cell sourcing, certification, lifecycle performance, warranty management, and replacement strategy remain important regardless of where the final system is assembled.
The next useful technical disclosure will be the plant’s MW rating and connection configuration. Those figures will reveal whether the 250MWh system is intended for relatively short, high-power response or longer energy shifting and will clarify how it complements the 500MWh of AzerEnerji storage commissioned earlier this year.
For now, the contractual milestone is defined: a $58.6 million financed turnkey package has moved another 250MWh of Azerbaijani battery capacity into delivery, with YEO responsible for the engineering chain from battery modules and controls through to the high-voltage interface that will connect them to the grid.
