Where do BESS projects most often suffer delays?
A practical analysis of the places where BESS projects most often lose time — from grid connection and infrastructure to systems integration.
Energy storage has now ceased to be a "new technology" and has become a fully-fledged element of energy infrastructure. That does not mean, however, that BESS projects have become easy to deliver. On the contrary, market data show that delay is not the exception but one of the basic parameters that has to be built into the project model from the very start.
In the ACCURE report, based on an analysis of more than 100 commercially operating BESS installations, only 2.5% of projects were commissioned ahead of schedule; 51% were delayed by 1–2 months, 34.5% by 3–6 months and 12% by 7–9 months. This means that the vast majority of projects do not reach their planned commercial operation date (COD) and that schedule slippage is the operational norm.
The same report also shows that commissioning problems are usually not the result of a single technical fault but of accumulated delays in deliveries, agreements, tests, integration and acceptance procedures. The data also indicate that around 40% of commissioning-phase problems stem from integration errors rather than from equipment failures.
Against this background it is increasingly clear that, in current market conditions, two areas constitute structural "bottlenecks": the grid connection process and the availability of high-voltage transformers. Transformers in particular have become the element with the longest lead time in the entire project.
Critical infrastructure (transformer and grid connection)
High-voltage infrastructure is most often the actual critical path of the project. It is in this area that the greatest market tensions are now observed. Growing demand for connection capacity and limited transformer availability mean that this process is no longer just an element of the schedule — it is becoming a factor that determines whether the project can be delivered at all.
In many cases the delivery time is now 24–36 months, an increase of around 70–100% compared with pre-2022 levels. This is due to the global shortage of production capacity, the limited availability of electrical steel and the sharp rise in demand driven by the energy transition.
Administrative and environmental processes
The formal project pathway is highly variable and non-linear. The most common sources of delay are appeals and public protests, the need to supplement documentation and differences in interpretation between institutions. Administrative risk is asymmetric — it may be short, but in extreme cases it extends the project by many months.
Technical requirements and safety
The area of technical requirements often becomes critical only at the final stage. The typical mechanism: the project meets the formal requirements but does not meet them under real conditions. This applies in particular to noise standards, cooling systems and fire-safety requirements. Exceeding noise limits can lead to acceptance being suspended and, in extreme cases, even to revocation of the operating permit.
Systems integration (EMS, SCADA, BMS)
A BESS is a multi-layer system, not a single device. The most common problems are a lack of system compatibility, communication errors and non-compliance with the operator's requirements. It is integration, rather than the technology as such, that is one of the main sources of problems in the commissioning phase. Many of these problems result from so-called interface risk, i.e. the unclear allocation of responsibility between project participants.
Impact on bankability and project profitability
A delay in COD has a direct, multidimensional impact:
- Postponement of the start of revenue generation (lowering NPV).
- Generation of financing costs (interest) despite the absence of revenues (lowering IRR).
- Impact on the ability to meet credit requirements (DSCR).
- In systems such as the Capacity Market, a delay can lead to the loss of a stable revenue stream.
A project that is profitable only on the assumption of full timeliness does not meet bankability criteria.
The Envalis approach
The Envalis methodology treats delay as one of the main parameters of the project model. This means that delay is explicitly included in the schedule, the moment of construction is separated from the moment of revenue generation, and risks are allocated to specific layers of the project. This approach makes it possible to assess project resilience realistically and to limit the risk of mistaken assumptions at the investment stage.