Home Energy assets Five things to consider when designing and commissioning high-performance solar-plus-storage projects – pv magazine International

Five things to consider when designing and commissioning high-performance solar-plus-storage projects – pv magazine International


Of pv magazine United States

When it comes to designing and building solar and energy storage projects, experience matters. Here are five things to consider when designing and commissioning a high-performance solar-plus-battery storage system, along with an actual case study of such a heavily loaded DC-coupled system.

  1. Model use case scenarios to maximize value

To truly optimize battery storage system (BESS) designs in solar projects, the use cases for PV and storage must be well understood and aligned with the financial model of the project. This requires a high level of project optimization and specialization, held only by the most experienced storage partners. For example, the team should be aware that storage systems can be effectively oversized in the first year, rather than scaled up, to match the degradation of PV modules and the exponential decrease in peaked solar output.

Decision dynamics vary depending on the architecture (AC versus DC coupling) and market applications. At a minimum, these hybrid systems allow projects to deliver more value to the grid by distributing electricity during peak demand periods; at best, they can improve solar performance, traverse turbulent grid conditions to keep the plant online, and enable value stacking on retail, wholesale, and merchant revenue targets.

  1. Plan early and often for energy storage security

Safety is the number one priority for solar plus storage systems, and planning should begin well before installation. Owners should consider security from the early stages of the project, including the development phase, and seek help from experts who can talk about product bankability, technical viability, risk mitigation and the many security aspects of their project. Before considering the use of any storage product, a thorough security due diligence process covering every component of the system should take place. This diligence ensures that an asset will reach its expected life while ensuring compliance with applicable codes and standards and local authorities having jurisdiction (AHJ).

A risk assessment methodology should focus on the causes and consequences of component-level failures and apply a single risk tolerance to assess whether protective measures provide a safe and acceptable outcome. Here is an example of an evaluation sequence used in a typical hazard analysis:

  • Determine your organization’s acceptable risk tolerance.
  • Assuming the failure occurs, determine the immediate consequence(s) of the failure.
  • Assess the probability of failure based on available safeguards.
  • Note the severity of the consequence(s).
  • Establish a level of risk based on the likelihood and severity of failure.
  • Apply current protective measures and reassess the level of risk.
  • List recommendations for bringing the risk to appropriate levels.
  • Implement the recommendations.

The product safety process should include, among others, the following critical steps:

  • Review product certifications and applied testing standards.
  • Review the manufacturer’s Failure Modes and Effects Analyzes (FMEA).
  • Review UL 1973, UL 9540A, and functional safety test results.
  • Ensure suppliers have quality systems in place for incident prevention.
  • Ensure suppliers have a sufficiently detailed emergency response plan or product-specific guidelines that assess systems for the recovery stage of the incident.

Using products without in-depth knowledge of them is inherently dangerous when it comes to designing energy storage systems. Although there are many lithium-ion technologies on the market, incorporating a deliberate recommendation process leads to the best-suited system for a given project. When the EPC has a strong knowledge base, it can do its best to manage the supply and due diligence of BESS products.

  1. Energy storage data infrastructure is complex

It is not uncommon to find professionals in the solar industry baffled by the long lead times required to properly commission energy storage systems. A common cause is the overwhelming amount of data needed to control, monitor, and secure systems appropriately. Much of this data is generated by one system, required by another to operate effectively, and stored in a third location, making data infrastructure and network planning of paramount importance. The earlier the design of the project and the more complete this planning, the more the system is likely to operate correctly until commissioning.

For large commercial, community, or large-scale projects, there are many battery modules, battery racks, cabinets, meters, and power electronics at every level. Each of these components connects to the energy management system (EMS) and data acquisition system (DAS), and any physical or software issue can cause a system warning or crash – and every system crash may cause a shutdown. Troubleshooting the DAS can be a hindrance to performance testing because the BESS subsystems are highly codependent. Networking should be worked out during the design phase. Standardizing the data infrastructure is extremely beneficial and redundancy will keep your system online.

Finally, consider the impact of data dependencies on each phase of system commissioning. For example, to perform solar capacity testing for a DC coupled system, data from the energy storage inverter will likely need to be accessed and referenced. This means that all network connections between the energy storage equipment and the DAS must be terminated prior to solar testing. EPC and energy storage vendor teams should work closely together to ensure a smooth commissioning process that minimizes downtime and delays.

  1. Monitor and control equipment conditions during construction

Batteries typically have temperature and humidity thresholds, which is why it is essential to have operating climate management systems in place not only during asset operation, but also during the pre-power-up period. between delivery and commissioning. On construction sites without auxiliary power, batteries can sit in the sun all day with internal temperatures reaching 150°F. Excessive heat and humidity will degrade the health of a battery and can lead to premature failure and future hazards. During construction, it is important to properly coordinate deliveries with temporary or permanent auxiliary power sources to maintain, control and monitor the condition of the batteries.

Conditioning and preventive maintenance are not limited to batteries. Long storage times can also cause unsuspected damage to a power conversion system. Without proper operation and heating, humidity control, and preventive maintenance, serious damage can occur to power modules, fans, control boards, capacitors, etc., creating a risk to safety during commissioning and a large bill to rectify or replace the unit.

  1. Share lessons learned from the field and asset operations

It may seem obvious, but field operators, project managers, commissioning engineers, and asset management professionals need to proactively share lessons learned for optimal success. Learning from team members on different projects across portfolios is one of the best ways to work around potential issues. In other cases, shared experiences can apply regionally, across similar use cases, and in particular on the design and implementation of a given product.

For example, slight changes made to a product from one generation to the next, such as a change in duct entry points, may not be updated in the supplier’s drawings at an early stage. By sharing this information before subsequent deliveries, site supervisors on other projects can make changes in the field and avoid delays. Other on-the-job learnings include rigging setup, pre-powering and commissioning the DAS, and using the pre-commissioning checklists.

Case Study: Ground Fault Detection of a DC Coupled System

One of the unique challenges of deploying heavily loaded DC-coupled power plants is designing appropriate and effective ground fault detection systems. In DC-coupled systems, the solar and energy storage systems aggregate on the inverter’s DC power bus. Due to the increase in the number of PV circuits (due to the high charging rate of the inverter) and energy storage system circuits combined in parallel, the inherent insulation resistance of the plant is lower , making a single sensing device more likely to trigger on changes in environmental conditions.

On a portfolio of multi-site solar and storage projects in the Northeastern United States, this ground fault detection issue was resolved through extensive collaboration with partners and a thorough redesign of the insulation monitor . A new system was deployed that could handle the unique conditions presented at each site without compromising safety or operational proficiency.

Early and Persistent Planning

A thorough due diligence process creates value and mitigates risk for the customer and gives confidence to system suppliers, leading to more efficient design, construction, commissioning and operations. Early and persistent planning is key to maximizing the full scope of value engineering opportunities on solar and energy storage projects.

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

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