JULY 26, 2021

Energy Storage Systems: How to Design and Commission High-Performance Projects

In the five years since Borrego began designing and building battery energy storage systems (BESS), we’ve successfully completed over 50 storage and solar-plus-storage projects — including some of the most technically complex projects in the industry. This early experience has given us unique insights into the engineering needs, safety procedures and commissioning steps that help deliver high-performance energy storage systems.

To help in the planning of your next energy storage project, we’ve put together some short lessons learned based on our hard-won experience, with practical considerations and advice for bringing these complex systems online.

Energy Storage System Experience Is Key

In terms of designing and optimizing for storage in solar projects, the use cases for the PV and storage installation must be well-understood and aligned around site constraints. This requires a high level of optimization and project understanding held by only the most experienced EPCs and integrators. For example, storage systems can be oversized, rather than augmented, for a given use case and size to match the PV and BESS degradation. The decision dynamics vary depending on AC or DC-coupling and when providing clipping recapture versus renewables shifting.

Plan Early and Often for Energy Storage Safety

Safety is priority number one and planning should start well before installation. A good EPC partner will be factoring in safety in the earliest stages of the project, including in the development, when they’re involved. Before Borrego ever considers using a storage product, we utilize our extensive safety diligence process covering each component within the system. This enables us to ensure we can address real safety concerns, including gaps in current codes and standards, as well as appease any concerns of the authorities having jurisdiction (AHJs). Using products without intimate knowledge of them is fundamentally dangerous when it comes to designing energy storage systems. We have reviewed a majority of lithium-ion-based technologies on the market and deliberately choose to recommend and install only a handful. We have a strong knowledge base, which is why we push hard to handle the procurement and diligence of the BESS. (We’ll take a closer look at storage safety considerations in the next blog post.)

Energy Storage Data Infrastructure Is Complex

While PV systems have well-understood and often straightforward design, installation, and commissioning processes — based on hundreds of gigawatts of experience — storage has varying levels of complexity and is less mature than solar. One example of such complexity is the data infrastructure needed for storage. 

For a commercial or utility scale lithium-ion system, you have numerous battery modules, battery racks, cabinets, and power electronics at all levels. Each of these pieces connects together to the data acquisition system (DAS), and if there’s a weak link it can cause a system warning or fault — and each system fault can cause a stoppage. Troubleshooting the DAS can be a hindrance to getting the system online as any issue that occurs may not be as tangible as a loose connection. We’ve learned that networking should be worked out during the design phase, standardization is tremendously beneficial, and redundancy will keep your system online.

Monitor And Control Battery Temperatures During Construction

Batteries have high and low limits for maximum and minimum temperature and frequency humidity thresholds, which is why fully integrated climate management is essential not only to operations and warranty but most importantly for system safety. On construction sites with no shade and with poor logistics, batteries could sit in the sun all day, with temperatures reaching 150°F and potentially damaging the batteries. High humidity can also degrade battery state of health and lead to operational hazards. During construction of large scale systems, it’s important to properly coordinate battery delivery and procedure temporary or early auxiliary power sources such that battery monitoring can be maintained and conditions controlled. 

Share Learnings from the Field 

It may seem obvious, but field operators, project managers, and commissioning engineers should proactively share their lessons learned from the field. Learning from team members on different projects across a portfolio is one of the best ways to get ahead of potential problems. In other cases, shared experiences can apply on a regional level, across similar use cases, and in particular on a given product design and implementation.

For example, we have found that slight changes in a product from one generation to the next, such as a modification in conduit entry points, may not get updated in early stage vendor drawings. By sharing this information ahead of later deliveries, the site supers at other projects were able to make field modifications and avoid delays. Other field learning include rigging set up, pre-energization and commissioning of the DAS, and the use of pre-commissioning checklists.

Kyle Cerniglia is Borrego’s Director of Engineering for Energy Storage. He is responsible for energy storage technology, engineering, and product integration for the EPC business.

Kyle Cerniglia

Director of Energy Storage Engineering

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