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48V Outdoor ESS · EG4 314Ah All-Weather + FlexBOSS21
This system pairs the EG4 WallMount 314Ah All-Weather battery (16kWh nominal, 12.86kWh recommended usable) with the EG4 FlexBOSS21 hybrid inverter. The battery is sealed to IP67 with built-in heaters and the inverter is NEMA 4X, so the whole system can mount outside on an exterior wall. It delivers up to 16kW of continuous output with PV and grid combined, takes up to 21kW of solar across 3 MPPT trackers, and is UL 9540 certified as a pair. Add the GridBOSS set to AC-couple an existing grid-tied solar system to battery backup.
Pre-matched components, sold together as one kit. Quantities scale with the set you choose.
Qty 1-6
16kWh nominal, IP67 sealed enclosure, internal heaters for cold-weather charging, smart BMS with active balancing.
Qty 1-3
Up to 16kW continuous output with PV and grid combined, 21kW max solar input, NEMA 4X outdoor enclosure.
1 per battery
Protects the battery power and communication wiring on outdoor installs. Battery-to-inverter power and comms cables included; paralleling cables included on multi-battery sets.
GridBOSS sets
Split-phase 200A microgrid interconnect device for whole-home backup, load management and AC coupling. Breakers not included.
IP67 battery and NEMA 4X inverter mount side by side on an exterior wall, so no garage or utility room space is needed.
Internal heaters keep the cells in charging range when temperatures drop, so winter solar still gets stored.
With the GridBOSS, the AC output of an existing grid-tied inverter connects to the GridBOSS GEN port, so you can add storage without reworking your roof.
Up to 16kW continuous with PV and grid working together, 12kW max battery charge and discharge power through the inverter.
Three MPPT trackers and five input strings handle large or multi-orientation arrays.
Battery and inverter talk directly over CAN/RS485, with Bluetooth and WiFi monitoring and over-the-air firmware updates.
Most home batteries need a conditioned indoor space. The EG4 314Ah All-Weather is sealed to IP67 and heats itself in the cold, so it can sit on the same exterior wall as the FlexBOSS21 and your main panel. Each battery ships with its own All-Weather conduit box, keeping the DC and communication wiring protected from rain and sun.
If you already have a grid-tied solar inverter that can't take a battery, the GridBOSS sets solve that. The GridBOSS sits between the grid, your main panel and the FlexBOSS21, and your existing inverter's AC output lands on its GEN port. Your panels keep producing as before, surplus charges the batteries, and the GridBOSS isolates the home from the grid during an outage. For new installs, the FlexBOSS21 takes up to 21kW of solar directly and runs the system on its own.
Battery - EG4 314Ah All-Weather
| Nominal voltage | 51.2 Vdc |
| Nominal energy capacity | 16 kWh |
| Usable energy (80% DoD) | 12.86 kWh |
| Rated capacity | 314 Ah |
| Max continuous charge current | 157 A |
| Max continuous discharge current | 200 A |
| Continuous charge/discharge power | 8 kW / 10.2 kW |
| Peak power | 12.8 kW (3 sec) |
| Charging temp range | 32-122°F |
| Discharging temp range | -4-131°F |
| Enclosure rating | IP67 (outdoor) |
| Self-heating | Yes, internal heaters |
| Weight | 309 lbs |
| Dimensions (H×W×D) | 34.6 × 21.7 × 9.3 in |
| Cycle life | 10,000 @ 0.5C, 80% DoD |
| Warranty | 10 years or 10,000 cycles |
| Continuous output (PV + grid) | 66.7A / 16 kW |
| Rated output power | 12,000W @ 240V |
| Peak power (0.5s / 1s) | 24,000W / 18,000W |
| Transfer time | 20ms default / 10ms configurable |
| MPPT channels | 3 (5 strings total) |
| Rated current per MPPT | 26A / 26A / 15A |
| Max utilized PV array | 21 kW |
| MPPT DC voltage range | 120-440 Vdc |
| Max efficiency (PV to grid) | 97% |
| Battery voltage range | 40-60 Vdc |
| Max charge/discharge power | 12,000 W |
| Max grid pass-through | 90 A |
| Idle consumption | <65 W |
| Dimensions (H×W×D) | 30.5 × 22.3 × 11.3 in |
| Enclosure rating | NEMA 4X |
| Connectivity | WiFi (included), cellular, Ethernet |
| Max parallel units | 16 |
| Warranty | 10 years |
Battery certifications: UL 1973, UL 9540A; DC ESS UL 9540 with FlexBOSS21. Inverter certifications: UL 1741, UL 1741 PCS CRD, UL 3141.
Choose the set that matches your load and storage needs. GridBOSS versions are available for 1-inverter sets.
| Tier | Inverters | Batteries | Capacity | Max Output |
|---|---|---|---|---|
| Standard | 1× | 1× | 16 kWh | 16 kW |
| Standard | 1× | 2× | 32 kWh | 16 kW |
| Standard | 1× | 3× | 48 kWh | 16 kW |
| Large | 2× | 4× | 64 kWh | 32 kW |
| Large | 2× | 6× | 96 kWh | 32 kW |
| 3-Phase | 3× | 6× | 96 kWh | 48 kW |
Yes. The 314Ah All-Weather battery is IP67 rated with built-in heaters, and the FlexBOSS21 is NEMA 4X. Both are designed for exterior wall mounting, and each battery includes an All-Weather conduit box for the wiring.
Yes, with a GridBOSS set. The AC output of your existing grid-tied inverter connects to the GridBOSS GEN port (AC coupling), and the FlexBOSS21 and batteries store the surplus. Your existing panels and inverter stay in place. Confirm compatibility of your specific inverter model with our team before ordering.
Battery-to-inverter power and communication cables, plus battery paralleling cables on sets with two or more batteries. One All-Weather conduit box is included per battery.
No. The GridBOSS ships without breakers, which are sized to your installation and sourced locally by your installer.
10 years on the battery (or 10,000 cycles) and 10 years on the FlexBOSS21 inverter.
Grid-tied systems require permits and utility interconnection approval in most areas. Installation by a licensed electrician or solar installer familiar with your local code is recommended.
Battery - EG4 314Ah All-Weather
Inverter - EG4 FlexBOSS21
Free shipping on all orders within the mainland US (Hawaii, Alaska and overseas territories excluded - a freight forwarder is required). Orders ship directly from our brand partners' warehouses across the U.S. Order confirmation is emailed immediately; if an item is unexpectedly backordered we notify you before your card is charged. In-stock items are processed within 1-4 business days (cut-off 4:00 PM EST), transit is 3-6 business days, and tracking is emailed within 24 hours of shipment. Typical delivery is 4-10 business days from purchase. Minimum order value is $69.
You have 30 days from the delivery date to initiate a return (35 days for orders placed Nov 25-30 and Dec 25-31). Items must be unused, in original packaging with tags attached, and returns require prior authorization from our team.
To start a return: +1 (307) 317-7213, hello@ecosolarkits.com, or live chat. Read the full return and refund policy
