Opinion piece by Nataraja M S – Head, Technical Support (APAC), Sungrow
With rapid increase in renewables in the power mix, the concern for better grid management is growing due to the fluctuating nature of RE power. Apart from having the ability to address the intermittent supply of renewable energy, energy storage assets can also offer a multitude of uses consisting of frequency regulation and ancillary services.
Large-scale energy storages are getting deployed in many parts of the world and likely to grow exponentially in coming years with more capacity addition of solar and wind projects. System integration technology is critical to the stable operation of large scale solar-plus-storage projects. Only few companies have proven solar-plus-storage system integration capabilities, though many companies do well in individual fields such as PV inverters, batteries, Power Conversion System (PCS), and Energy Management System (EMS).
Given the condition that different applications put different requirements on energy storage systems, there is no unified standard for energy storage system design and cost management. This variability leads to a grey zone due to the uneven integration capabilities and the low price competition.
The most critical aspect of energy storage system integration is the safety of the battery system. A qualified system protection design can monitor the operating status of cells, modules, battery clusters, battery management system (BMS) in real-time, enables pre-alarm and faults localization. If a fault occurs, it can protect the system by fast-breaking and anti-arc protection. Otherwise, minor faults can easily evolve into major problems.
The challenges are also related to battery life, where the temperature control system for energy storage is paramount. Particularly, the thermal simulation and experimental verification, air duct design of storage containers, HVAC configuration should strictly be controlled, or it may lead to the uneven temperature of lithium-ion batteries and hence aggravate battery instability.
The efficient integration:
The solar-plus-storage solution relies on deep analysis and technology integration of the whole system instead of a mechanical combination of two systems, to achieve a leap forward in terms of efficiency and performance.
Technically, the hybrid system needs to ensure the stable operation of PV, energy storage and the grid, creating smooth communication among hardware, software and systems. There exist a variety of devices from different manufactures, so compatibility becomes a major challenge for the integrator who needs to be adept at all the protocols.
Particularly, the solar-plus-storage system needs to fully consider the management of batteries and PCS when dispatching the output, to improve the safety and ROI of the whole hybrid plant. So only an experienced company which excels at both energy storage and PV industry can integrate an efficient system.
In addition, efficient energy management through an intelligent control unit based on PV power prediction and millisecond response characteristics of energy storage is also crucial to safe operation and maximum yields of the whole system. A rapid communication mechanism bridged among PCS, BMS and EMS can ensure the safety of the battery and the entire system.
There’s no doubt that the advancement of technology allows more integration between renewable energy and storage, indicating a mature multiple-energy era is imminent. The marketplace will see the integrated energy storage system which is more cost-optimized, safer and more efficient, getting rid of the instability and intermittent constraints of renewable energy.
By Nataraja M S – Head, Technical Support (APAC), Sungrow