This listing covers a 48V LiFePO4 battery and inverter package: BigBattery ETHOS batteries paired with an EG4 FlexBOSS21 all-in-one energy storage system (ESS). The kit is sold as a variable parent with 11 configuration options, ranging from 10.24kWh to 46.1kWh of usable capacity. Use it for grid-tied or off-grid home backup, sized to your PV array and load.
Note: If you would like to review the manufacturer Product Specifications, Warranty, Brochure, etc., for this system, please refer to the "Resources (System Manuals and Warranty)" Tab above on this page.
Why This Configuration Matters
ETHOS batteries use LiFePO4 (Lithium Iron Phosphate) chemistry, the standard for stationary home storage because of its thermal stability and long cycle life compared to older lead-acid systems. The system is rated to UL9540, a certification standard specific to energy storage systems, which matters when you're integrating battery and inverter equipment into a home electrical system tied to code inspection. This package bundles the battery bank with an EG4 FlexBOSS21 ESS, meaning the inverter, charge controller, and battery management coordination are designed to work as one system rather than being pieced together from separate vendors.
Battery Characteristics
- Chemistry: LiFePO4 (Lithium Iron Phosphate)
- System Voltage: 48V nominal
- Capacity Range: 10.24kWh to 46.1kWh usable, depending on selected variant
- Certification: UL9540
- Compatible PV Input Range: 21kW–63kW, depending on configuration
Wiring & Configuration Limits
This is a parent listing with 11 available capacity configurations built around the 48V ETHOS + FlexBOSS21 platform. The specific number of battery modules, and how they combine to reach a given kWh total, depends on which of the 11 variants you select. Do not mix ETHOS batteries with other lithium chemistries or with lead-acid batteries in the same bank. Do not combine battery modules of different ages or cycle histories in the same string — this leads to state-of-charge imbalance across the pack. [NEEDS VERIFICATION: specific series/parallel module count and BMS max continuous discharge/charge amperage were not included in the source data for this listing.]
Pro-Installer Tip
Series and parallel expansion mistakes are the most common return reason on stacked lithium ESS builds. Before you wire additional battery modules into an existing FlexBOSS21 setup, confirm the firmware and BMS communication protocol match across all modules — mismatched firmware versions on lithium packs can cause a BMS lockout that reads like a dead battery but is actually a communication fault. This protects against premature pack failure and false low-voltage shutdowns. Verify state-of-charge alignment across modules with a shunt-based battery monitor before closing up the install, not just the inverter's onboard display. LiFePO4 systems like this one are typically designed for 80–100% depth of discharge; confirm your specific variant's DoD rating in the manufacturer documentation before setting your inverter's cutoff.
Key Benefits
- Scalable capacity from 10.24kWh up to 46.1kWh across 11 configuration options, so you can size to current load and expand later within the same product family.
- UL9540 certification supports code compliance conversations with your installer or AHJ (Authority Having Jurisdiction).
- Integrated battery + inverter pairing (ETHOS + FlexBOSS21) reduces compatibility guesswork versus sourcing components separately.
- LiFePO4 chemistry avoids the sulfate buildup and shortened lifespan associated with flooded or AGM lead-acid banks in daily-cycling applications.
Technical Table
| Spec | Value |
|---|---|
| Voltage | 48V nominal |
| Chemistry | LiFePO4 |
| Usable Capacity Range | 10.24kWh – 46.1kWh |
| Certification | UL9540 |
| Compatible PV Input | 21kW – 63kW |
| Inverter/ESS | EG4 FlexBOSS21 |
| Battery Platform | BigBattery ETHOS |
| Max Continuous Discharge (A) | [NEEDS VERIFICATION] |
| Cycle Life | [NEEDS VERIFICATION] |
| Operating Temp Range | [NEEDS VERIFICATION] |
| Dimensions | [NEEDS VERIFICATION] |
| Weight | [NEEDS VERIFICATION] |
| Terminal Type | [NEEDS VERIFICATION] |
Note: See "Resources (System Manuals and Warranty)" Tab above for full specifications.
Compatibility & Fitment
This system is built around the EG4 FlexBOSS21 ESS and BigBattery ETHOS battery platform. It is designed for grid-tied or off-grid home backup applications matched to a 21kW–63kW PV array, depending on the variant selected.
Compatible with: BigBattery ETHOS battery modules within the same product family; PV arrays sized within the stated 21kW–63kW range for the selected configuration.
NOT compatible with / NOT included: This is not a drop-in replacement for lead-acid or AGM battery banks — do not wire this pack into an existing lead-acid charging setup. Standard lead-acid chargers are NOT recommended for this system. Mixing ETHOS modules with other battery brands or chemistries in series or parallel is not supported. PV panels, mounting hardware, and rapid shutdown devices are not included unless explicitly listed in your selected variant.
FAQ
What chemistry does this battery use?
It uses LiFePO4 (Lithium Iron Phosphate), not lead-acid, AGM, or Gel.
What capacity range is available?
The parent listing spans 11 configurations from 10.24kWh to 46.1kWh usable capacity.
Is this certified for grid-tied residential use?
The system carries UL9540 certification, which applies to energy storage systems used in stationary applications like home backup.
Can I mix this battery with an existing lead-acid bank?
No. Do not mix LiFePO4 ETHOS batteries with lead-acid, AGM, or Gel batteries in the same bank or charging circuit.
What PV array size does this system support?
Depending on the configuration selected, the system is designed for PV arrays between 21kW and 63kW.
Options & SKUs
| Variant | SKU | Price (USD) |
|---|---|---|
| variable parent (11 variations) | K0241-V | 6004.99 |
The price shown reflects the lowest available variant. This product has 11 total configuration options; individual SKU-level pricing for each of the 11 variants was not provided in source data beyond the parent SKU above. Contact us before you order if you need help matching kWh capacity to your specific load or PV array.
Warranty & Support
Warranty terms, manufacturer specifications, and brochures for this system are located in the "Resources (System Manuals and Warranty)" Tab above. If something in this listing doesn't match what you find there, ask us before you order — we always reply back.
