Building-Connected Energy Storage Systems: Installation Considerations for Developers and EPCs

Energy Storage Systems (ESS) have become a critical component of modern energy supply for Commercial, Industrial and DG users. Building-connected Energy Storage Systems (ESS), in particular, offer a range of benefits, from load shifting and demand reduction to emergency backup power. With the cost of lithium-ion batteries down 89% since 2010, it comes as no surprise that the global energy storage market is posting record numbers with a projected growth of 20% in the US for 2025. Building-connected ESS offer a significant cost savings potential for commercial operations. However, project roll-out requires careful consideration of technical, regulatory, and operational factors. Within those ramifications, installers have to make sure the solution delivers on the features promised to the project owner. Let’s shed light on the pivotal aspects of a successful ESS installation.

Optimizing the Location of Commercial Energy Storage Systems

One of the most critical steps in designing a building-connected ESS is finding the optimal location for the battery system. Safety considerations, utility interconnection, and local building codes play a role. But let’s not forget about cost; positioning the ESS in the right spot can save hard dollars on installation and operation down the road.

Key Considerations for ESS Placement:

• Setback Requirements: Many jurisdictions require ESS installations to maintain a minimum distance from buildings, property lines, and public rights of way. For example, the International Fire Code mandates specific setbacks to mitigate fire risks.
• Accessibility and Maintenance: Equipment manufacturers often require clearances for maintenance and repair access. Installations need to follow manufacturer guidelines.
• Structural Features: ESS units are heavy and require a robust foundation. Structural engineering may be needed to ensure the chosen location can support the weight of the system. This may involve soil testing and the construction of reinforced concrete pads.
• Proximity to Interconnection Points: We all love saving on costs and here is an opportunity: ESS units should be located as close as possible to the point of interconnection with the building’s electrical system. This reduces the need for extensive trenching, conduit runs, and additional wiring.
• Fire Safety: In-depth knowledge of local fire codes is an obvious must. Depending on jurisdiction, they can extend to fire safety measures, such as the placement of fire hydrants and the use of bollards. On larger projects, firewalls may be required to separate multiple ESS units.
• Power Studies: For certain projects, studies, such as arc flash, short circuit, equipment withstand, and coordination studies may be indicated in order to comply with, e.g., arc flash energy requirements.

Before installing an ESS, all relevant factors have to be considered to find the ideal location. Compliance reviews will often result in a map overlay of restricted areas. In a value engineering approach, the remaining spaces can then be evaluated based on their projected system cost and efficiency to select the optimal location.

Integration with Energy Management Systems

The Energy Management System (EMS) is the brain of a building-connected ESS. It monitors and controls the flow of energy between the ESS, the building’s electrical loads, and the grid. The EMS needs to be properly integrated to make sure the system operates efficiently and meets the energy objectives of the client.

When looking at the technical integration, current transformers and other sensors need to be placed effectively, allowing the EMS to accurately monitor energy flows. Adequate engineering means the system can make real-time adjustments to optimize performance while staying within the bounds of utility rules.

Key Functions of the EMS:

• PV Energy Storage: EMS are predominantly used in buildings that have solar PV systems. In general, the EMS directs excess solar energy during the day to the battery storage which is used during periods of low solar production (i.e., evening and night).
• Load Shifting and Demand Reduction: The EMS controls when energy is stored in the ESS and when it is used, reducing the building’s reliance on grid power and lowering energy costs.

Navigating Utility Regulations

Utility requirements are a huge topic in the engineering of building-connected ESS. They dictate how the system can interact with the grid and have to be carefully assessed to avoid costly re-work or non-compliance. Utility rules are unpredictable across different jurisdictions and can be quite disorienting, making local expertise and a deep understanding of regional requirements a fundamental ingredient for project success.

Key Utility Considerations:

• Charging and Discharging Restrictions: Many utilities prohibit ESS units from charging directly from the grid or exporting stored energy back to the grid. The restrictions are often tied to time-of-use rates, with utilities trying to prevent customers from practicing energy arbitrage.
• Export Limitations: Other utilities may not completely prohibit, but limit the export of stored energy back to the grid. This is particularly common in areas with high solar penetration, where excess energy exports could destabilize the grid.
• Interconnection Standards: Each utility has its own set of interconnection standards, which govern how the ESS connects to the grid. The standards often include requirements for relay protection and energy management systems. These have to be designed by the engineer of record and are separate from the EMS and ESS components.

Examples of local utility requirements:

• In California, utilities like PG&E and SCE have specific rules for ESS installations, including restrictions on grid charging and export limitations.
• In New York, Con Edison requires ESS units to comply with stringent interconnection standards and may mandate the use of blast walls for safety.
• In Texas, ERCOT has unique rules for ESS participation in the wholesale market, allowing systems to share energy with the grid.

Commercial ESS Integration Scenario

Consider a commercial building in California with a solar PV system and ESS. The local utility, PG&E, prohibits grid charging and restricts energy exports. The EMS is programmed to:

1. Charge the ESS only from solar PV during the day.
2. Discharge the ESS only to serve on-site loads in the evening, avoiding any export to the grid.
3. Use relay protection as a fail-safe to shut down the system if it detects any violation of utility rules.

This approach ensures compliance with PG&E’s requirements while maximizing the economic and operational benefits of the ESS.

Fire Protection for ESS

Most ESS units come equipped with built-in fire suppression systems. However, additional measures may be required to meet local codes and ensure safety. By accounting for all relevant requirements, the developer facilitates a smooth design and construction process, that avoids costly re-work and work stoppages, setting the project up for success.

Key Fire Protection Considerations:

• Based on local requirements, ESS installations may need to use water-based fire suppression systems rather than the chemical systems provided by manufacturers.
• In certain jurisdictions, such as New York City, ESS installations might require blast walls to help contain potential explosions.
• Fire services need clear access to ESS installations in the event of an emergency. So, fire hydrants and other emergency equipment must be readily accessible.

Optimizing the System with Value Engineering

One of the advantages of working with an experienced ESS installer is that they will optimize the system integration through value engineering. What does that include?

1. When combining ESS with solar PV systems, the combined capacity of the two systems does not necessarily need to equal the sum of their individual capacities. By utilizing the EMS to control the flow of electricity, the system can be sized for a lower total capacity, saving money.
2. Appropriate location planning and system integration can reduce the need for extensive trenching, conduit runs, and additional wiring, leading to substantial savings on materials and labor.

Partnering with Experts for a Seamless ESS Integration

Installation of a building-connected ESS is often a complex process that requires expertise in electrical engineering, structural engineering, and an ability to effectively manage and coordinate between various other disciplines. In partnering with a seasoned engineer, developers and EPCs can ensure compliance of their projects and more often than not benefit from cost savings.

At Pure Power Engineering, we are experts in the technical integration of ESS systems, guiding our clients through the complexities of location optimization, EMS integration, fire protection, and utility requirements. We aim is to deliver systems that live up to client expectations, offering cost-effective and reliable energy solutions.

Find out more about our ESS solutions or get in touch with us!