FOX ESS: AC1- 5.7-US + 12kWh Battery + Hub AC1-5.7-US + 12kWh Battery + Hub Expand your system easily by simply adding additional batteries. There are six battery size options, and seven batteries can be installed in series, providing up to 27.8 kWh of storage capacity. EASY INSTALLATION HIGH VOLTAGE TYPE 4X REMOTE MONITORING Flexible configuration, plug and play set-up. Compatible with high-voltage batteries for maximum round-trip efficiency. Engineered to last with maximum flexibility. Suitable for outdoor installation. Monitor your system remotely via smartphone app or web portal.