EG4 FlexBOSS 21 + GridBOSS Battery Backup Kit (No Solar) | 12kW 120/240V | 32kWh Battery
EG4 FlexBOSS 21 + GridBOSS Battery Backup Kit (No Solar) | 12kW 120/240V | 32kWh Battery - Image 2
EG4 FlexBOSS 21 + GridBOSS Battery Backup Kit (No Solar) | 12kW 120/240V | 32kWh Battery - Image 3
EG4 FlexBOSS 21 + GridBOSS Battery Backup Kit (No Solar) | 12kW 120/240V | 32kWh Battery - Image 4

EG4 FlexBOSS 21 + GridBOSS Battery Backup Kit (No Solar) | 12kW 120/240V | 32kWh Battery

$13,531.89

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A battery backup kit built around the EG4 FlexBOSS 21 hybrid inverter with GridBOSS.

  • 12 kW continuous 120/240V split-phase output
  • Storage: 32 kWh (2 × 16 kWh Wall/Floor-Mount) EG4 WallMount LiFePO4
  • Grid-connected battery backup: charges from the grid now, add solar later

Solar panels not included.

SKU: WEB-EG4-FLEX21-GRIDBOSS-NOPV-32KWH Categories: , , , Brand:

Whole-Home Hybrid · Backup · Off-Grid

EG4 FlexBOSS 21 + GridBOSS Battery Backup Kit (No Solar) | 12kW 120/240V | 32kWh Battery

This kit is built around the EG4 FlexBOSS 21 hybrid inverter with GridBOSS, delivering 12 kW of continuous 120/240V split-phase output and 32 kWh (2 × 16 kWh Wall/Floor-Mount) of storage.

At a Glance
  • 12 kW continuous AC output, 120/240V split-phase
  • Surge capacity up to 24 kW for motor starting
  • Battery options: 32 kWh (2 × 16 kWh Wall/Floor-Mount) (EG4 WallMount LiFePO4)
  • Grid-connected battery backup: charges from the grid now, add solar later

Choose Your Configuration

Battery Storage 32 kWh (2 × 16 kWh Wall/Floor-Mount)
Rack-Mount batteries install in a battery rack or cabinet; Wall/Floor-Mount batteries mount on a wall or stand on the floor.

Options are offered in specific combinations; available combinations are shown in the selector above.

System Overview

This battery-only kit charges from the grid and backs up your home during outages; compatible solar can be added later.

Ideal Applications

  • Whole-home backup for a typical home with one HVAC system (up to 200A service)
  • Full-time off-grid family homes
  • Water pumping and workshops

What’s Included

  • One EG4 FlexBOSS 21 hybrid inverter with GridBOSS
  • EG4 WallMount LiFePO4 (battery configurations), with mounting and battery cabling
Installation note: Site-specific wire and conduit, breakers, service and interconnection equipment, and permitting materials may be required. Utility and AHJ requirements vary; final design must follow manufacturer instructions and applicable code.
Weight 778.2 lbs
Dimensions 72 × 48 × 54 in
Brand

Inverter Platform

EG4 FlexBOSS 21 + GridBOSS
Inverter Quantity

Single
Continuous Output

12 kW
Inverter Size (KW)

10KW-15KW
Output (V)

120V/240V
Grid Connection

Grid-Interactive Hybrid (Can Export)
Generator Compatible

Yes
Inverter Type

All-in-one Inverter
Battery Capacity (KWH)

30KWH-40KWH
Battery Storage

32 kWh
Rapid Shutdown

None

What Can It Power?

Built around the EG4 FlexBOSS 21 with GridBOSS, a hybrid inverter paired with GridBOSS for whole-home backup, this kit delivers 12 kW of continuous 120/240V split-phase output.

12 kW
Continuous output, 120/240V split-phase
24 kW
Surge for motor starting
32 kWh
Battery storage options
What you can run
Everyday essentials

0.5–1.5 kW

Refrigerator and freezer, LED lights, ceiling fans, phone and laptop charging, modem, router and TV. These small and cycling loads are the starting point for long outage coverage.

Kitchen, laundry & larger loads

1.5–5 kW each

Microwave, coffee maker, washer or dishwasher as needed. An electric water heater, dryer, oven or range can use a large share of the output, so stagger them instead of running them together.

Cooling, pumps & shop tools

Check starting current

A compatible mini-split, central HVAC, well pump or shop tool may run when its running demand and starting current fit within 12 kW continuous and 24 kW surge. Check the actual equipment; tonnage or horsepower alone doesn’t confirm it. A soft starter can help some compressors.

Illustrative operating mixes
Refrigerator/freezer, LED lights, internet, TV and fans0.5–1.5 kW
Essentials + microwave or coffee maker2–3.5 kW while it runs
Essentials + a smaller inverter mini-split1.5–3 kW
Essentials + a 4.5 kW electric water heater5–6 kW while heating
Essentials + 3-ton central A/C running4–6 kW plus a large starting surge
Plan around the limits
Add up the loads that run at the same time and allow for motor starts. For a 12 kW split-phase system, keep loads balanced across the two 120V legs: a heavily loaded leg can reach its limit before the total does. A larger battery adds runtime but doesn’t raise the inverter’s output. Examples are planning illustrations, not guaranteed appliance packages.

How Long Will It Run?

Battery size sets how much energy you have. These battery-only estimates use 80% of nominal storage delivered to loads (25.6 kWh from 32 kWh).

0.5 kW · Lean essentials / light overnight use
32 kWh

51.2 hrs

1 kW · Essentials with more appliance use
32 kWh

25.6 hrs

2 kW · Moderate household use
32 kWh

12.8 hrs

4 kW · Higher sustained use
32 kWh

6.4 hrs

6 kW · Heavy sustained use
32 kWh

4.3 hrs

12 kW · Full rated output
32 kWh

2.1 hrs

Runtime = usable battery energy ÷ average load, starting full, with no solar, grid or generator. Average load includes cycling: a 1 kW appliance running half the time averages about 0.5 kW. Actual results depend on settings, battery condition, temperature and system consumption.

At 12 kWh per day
2.1 days on 32 kWh
At 24 kWh per day
1.1 days on 32 kWh

Cooling, heating and electric water heating can change daily totals substantially.

Charging Without Included Solar

This kit doesn’t include solar panels. It charges from the grid or a generator, and compatible solar can be added later.

When Solar Isn’t Enough

Utility available
Solar powers the home first and charges the battery; GridBOSS manages the grid connection and can export surplus where your utility allows.
Grid outage: solar + battery
The system supplies only the circuits connected to its backup output, from solar and stored energy. Plan for the 12 kW output limit, battery discharge limits and motor starts, and shed large loads to extend runtime. A properly configured compatible generator can carry extended low-sun periods (not included).

Why This System?

The EG4 FlexBOSS 21 + GridBOSS Battery Backup Kit (No Solar) is built around the EG4 FlexBOSS 21 with GridBOSS, a hybrid inverter paired with GridBOSS for whole-home backup. Match the configuration to your daily energy use, the loads that run together and your installation.

12 kW for a useful mix of loads

120/240V split-phase output runs common household circuits and compatible 240V equipment. Manage what runs together and check motor starts for HVAC, pumps or shop tools.

GridBOSS whole-home control

GridBOSS manages the grid, generator and home loads for whole-home backup.

Three MPPT inputs per inverter

Flexible string layout for multiple roof faces.

Parallel-capable

Add FlexBOSS units to scale output for larger homes.

Choose Your Size

No solar included · 25.6 kWh usable
32 kWh

Battery-only backup: charge from the grid now, add solar later.

Only the combinations shown in the product selector are offered. Every option uses the same EG4 FlexBOSS 21 with GridBOSS configuration.

Plan the system around your site
This platform can export solar to the utility where your utility allows and your interconnection agreement permits. Solar panels, site-specific electrical materials and installation are additional.

Other Sizes on This Platform

Dual EG4 FlexBOSS 21 + GridBOSS Hybrid Whole-Home Solar Kit | 24kW 120/240V | 21.6kW Solar | 48kWh Battery
EG4 FlexBOSS 21 + GridBOSS Hybrid Whole-Home Solar Kit | 12kW 120/240V | 13.6–14.4kW Solar | 32–48kWh Battery
Triple EG4 FlexBOSS 21 + GridBOSS Hybrid Whole-Home Solar Kit | 36kW 120/240V | 29.6kW Solar | 64–80kWh Battery

Reference: EG4 FlexBOSS 21 with GridBOSS manufacturer information.

Frequently Asked Questions

Does this kit include batteries?
Yes: 32 kWh (2 × 16 kWh Wall/Floor-Mount) of EG4 WallMount LiFePO4, per the option you choose.
Will it power my home during an outage?
Yes, for the circuits connected to its backup output (or the whole home with a whole-home interface).
What output does it provide?
12 kW continuous at 120/240V split-phase.
Can I sell excess solar to the utility?
Yes, where your utility allows and your interconnection agreement permits.
Can I connect a generator?
Yes. Use an inverter-style generator (3–5% THD) with 2-wire auto-start for automatic control. Generator not included.
Are all breakers, wire and conduit included?
Not necessarily. Site-specific wire, conduit, breakers, service upgrades and interconnection hardware may be required.
Will this eliminate my electric bill?
No specific savings are guaranteed. Rate structure, fixed charges, export compensation, usage and production all affect the final bill.
Do I need permits or utility approval?
Most installations need permits and inspections, and grid-connected systems need utility interconnection approval. Requirements vary by location.
Can this be installed DIY?
That depends on your jurisdiction and utility. Electrical work must follow manufacturer instructions, adopted code and any licensing requirements.
How do I know which configuration is right for me?
Use our kit selector, or contact SanTan Solar to match the system to your loads, usage and runtime needs.
Still have questions?

Contact SanTan Solar for help matching the system to your project.

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