Real-world Thermal Performance of a PV-coupled Battery with Smart Passive Thermal Regulation
Objective: The performance and life of Lithium ion batteries are highly sensitive to temperature swings. Reliance on active cooling systems in larger centralized storage increases the maintenance needs, poses safety risks and can cause increased down time while reducing the overall efficiency. This presentation will include the test results and performance of a novel passive thermal regulation built around a Lithium Iron Phosphate battery. This enables a new class of safe, modular energy storage systems that can be coupled behind solar PV modules with a long reliable life span.
Methods: These PV-coupled energy storage units were deployed at a variety of real-world sites to study their performance under both hot and cold climates under different load profiles. In addition to real-world sites, few units were tested at National labs and third party test facilities to further validate the thermal regulation technology. These thermal results were then integrated with a computer model of battery aging and performance.
Results: These tests consistently measured the average and peak temperatures of the battery to be lower than that of the control unit / ambient under hot conditions. The cells were maintained below 37°C (99°F) for most of its life even under hot summers reaching above 55°C (131°F) without any parasitic energy consumption for cooling (passive). Under sub-freezing conditions the battery is kept around 10°C (50°F) while consuming a fraction of the power as would otherwise be needed. This ensures charging safety and a higher retention of usable capacity in cold operation. The test results will be shared as plots and key performance metrics will be presented.
Conclusion: The smart passive thermal regulation keeps the PV-coupled energy storage (battery) in a narrow range of temperatures to ensure long life and safe operation, which unlocks reductions in complexity and cost of adding storage to solar projects.