Whether you're looking to reduce grid dependence, maximize solar production, or prepare for power outages, this bundle delivers a complete energy storage solution built for long-term performance. Pairing the EG4 FlexBOSS21 Hybrid Inverter with OutBack EnergyCell 5 batteries creates a powerful system capable of supporting whole-home backup, daily energy savings, and future expansion.
Powerful Whole-Home Backup: Deliver up to 16kW of continuous output while solar is producing, with up to 12kW available from battery power alone. The FlexBOSS21 is capable of starting demanding household loads, including up to a 5-ton air conditioner, helping keep your home powered when the grid goes down.
Maximize Solar Production: Three independent MPPTs support up to 21kW of recommended PV input, giving installers greater design flexibility while helping homeowners capture more solar energy throughout the day.
Expandable Energy Storage: The modular EnergyCell 5 platform makes it easy to increase storage capacity as your energy needs grow. Whether you're planning for future home additions, EV charging, or increased backup runtime, the system is designed to expand without replacing your existing equipment.
Built for Long-Term Reliability: The OutBack EnergyCell 5 utilizes Lithium Iron Phosphate (LiFePO₄) cells, an active balancing Battery Management System (BMS), and independent module protection to deliver dependable performance, low maintenance, and a design life of more than 10 years.
UL 9540 DC ESS Certified Battery System: The OutBack EnergyCell 5 battery is UL 9540 ESS certified, and when paired with the EG4 18kPV inverter, it forms a tested Energy Storage System (ESS) designed to support code-compliant residential backup and storage installations.
Ideal for whole-home backup power, grid-tied solar with battery storage, off-grid properties, and residential energy independence projects where scalable energy storage, advanced monitoring, and long-term reliability are essential.
EG4 FlexBOSS21
Max Continuous Output: 16kW w/ PV & Grid ; 12kW w/ Batteries Only
Peak Power: 24,000W (.5 sec) | 18,000W (1 sec)
Recommended Max. Solar Array Power: 21kW
Enclosure Rating: NEMA 4X
Outback Power EnergyCell 5
Nominal Voltage: 51.2V
Continuous Charge / Discharge Power: 5kW
Outdoor Rating: IP65
Certifications: UL 9540A, UL 1973, UL9540
Please Note: Lifetime Customer Support is based in Texas and available via phone and email. We strongly recommend using a certified solar installer and/or master electrician for professional installation. Please note that additional components may be required for your installation.
Have questions or need assistance? Our support team is here to help! Give us a call at 903-441-2090.
EG4 FlexBOSS21 Spec Sheet
EG4 FlexBOSS21 User Manual
Outback Power EnergyCell 5 User Manual
Outback Power EnergyCell 5 Integration Sheet
Meet the EG4 FlexBOSS21 – the next-level hybrid inverter that’s bigger, more powerful, and more affordable than the EG4 18kPV. With 16kW continuous output, 21kW PV input, and seamless integration with the EG4 GridBOSS, this inverter is built for serious solar setups. But is it right for you? We take a first look at it to break down its features, what we like, and what you need to know before buying.
In this video, we provide an overview of the Outback Power EnergyCell 5, a lithium iron phosphate battery designed for residential and small commercial energy storage applications.
OutBack
SKU: BNDL-OB002
EG4 Electronics
SKU: 1526018-02
Versatile and Powerful Hybrid Inverter ...