Sol-Ark 12kW Inverter with Fortress Power eFlex 16.2kWh Battery Storage Kit

Adding storage with your PV system can be simple. Whether you have an existing grid-tie system or are planning a new project, Sol-Ark and Fortress offer a combined solution that will help you keep the lights on and your home office running during utility interruptions. “Closed-loop” communication and streamlined installation make integrating solar with storage now easier than ever.

Use with or without solar panels as a backup for your critical loads or to offset high TOU utility rates with peak load shaving. Rapid shutdown compatible APSmart devices easily integrate with new solar roof installations with UL 1741 Rule 21 compliance for a complete solar and storage solution that truly is an all-in-one compatible solution.


Components Included
Sol-Ark 12kW All-In-One-Hybrid 48V Inverter Qnty. 1
Fortress Power 5.4kWh eFlex Lithium Iron Phosphate Battery Qnty. 3
Fortress Power Battery Wall Mount Enclosure Qnty. 3
FW500 DC Enclosure Qnty. 1
Sets of 2/0 Battery to Inverter Red and Black Cables Qnty. 3

Sol-Ark 12K > 12kW 48 Volt All-In-One Solar Generator – Inverter
Manufacturer Part Number: 12K

Sol-Ark 12K All-In-One Solar Generator System

Parallel Stacking (1-9), Grid Sell, Meter Zero, Time of Use, Smart Load, Peak Shaving, 20kW Peak Power, 9.6kW AC Coupling

  • DC Transformerless: Boosts PV energy 10-20% without increasing PV array size and reduces storage inverter costs up to 30%
  • Battery Efficiency: Improve battery efficiency by 10-15%; Partial Charge Carbon AGM’s round trip efficiency is 98% vs. wet cell 80%
  • Easy to Install: Sol-Ark 12K’s All-In-One design cuts install time in half. With 2x MPPTs, and 9kW continuous / 20kW peak inverter, a user-friendly wiring area, and remote monitoring built-in.
  • U.P.S.: Sol-Ark 12K acts as a massive uninterruptible power supply with a lightning-fast 4ms transfer time.

Approved for: UL 1741 SA Rule 21, HECO, & Canada PREPA Approved for Puerto Rico 120/240 & 208V

Max allowed PV DC Capacity 6,500W+6,500W = 13,000W
Max PV power delivered to Battery & AC outputs 12,000 Watts
Max DC voltage 500V@18A, 450V@20A
MPPT voltage range 150-425V
MPPT Starting Voltage 175V
Number of MPPT 2
Nominal AC Output Voltage 120/240/208V split phase
Peak Inverter Efficiency 97.5%
Continuous AC power to Grid (On-Grid) 9000W 37.5A L-L (255 V)

4800W 40A L-N (120V)

Continuous AC power to Loads (Off-Grid) 8000W 33A L-L (240V )

4800W 40A L-N (120V)

Battery Type Lead-Acid or Li-Ion
Nominal DC Input 48V
Capacity 50 – 9900Ah
Grid to Battery Charging Efficiency 96.0%
Dimensions (H x W x D) 30.0” x 18.30” x 10.00”
Weight 78 lbs

Product Features

  • Next-Generation Efficiency
    3X Better! Only 3.5% losses vs. 14% in today’s battery-based systems
  • Split Phase & Three Phase
    Sol-Ark’s 12K pumps out power just like the grid, allowing you to power 120V/ 240V and 208V appliances
  • Grid-Tied, Hybrid, Off-Grid
    Manages power from Solar, Battery, Grid, Load, and Generator simultaneously
  • Flexible
    Sol-Ark is expandable from 5 to 52 (16.5 kW) solar panels and 0-32 batteries. Per 12K unit.
  • 10-Year Standard Warranty
    No need for additional warranties. The 12K comes standard 10-year warranty right out of the box.

Helpful Hint with Sol-Ark hybrid inverters: Unlike most string inverters – Sol-Ark hybrid inverter solution will not have a complete power loss for a series string of modules if one of the panels goes bad (stops producing) *** so as long the total voltage of the remaining panel meets or exceeds the min MPPT voltage range of 150VDC.

Fortress Power > 48 Volt 5.4kWh (105AH) Lithium Iron Battery

The eFlex 5.4 kWh 48 Volt Lithium Iron Battery by Fortress Power is a safe, scalable solution for any project’s energy storage needs.

With built-in data storage and Wi-Fi for remote troubleshooting and monitoring. The eFlex is light years ahead of the pack. Additional features, such as the Smart Battery Management System (BMS) includes relay disconnects, closed-loop communication for many hybrid inverters, cell voltage, and temperature monitoring, and cell balancing to maximize reliability and longevity, as well as wifi for internet-of-things compatibility.

The Fortress Power eFlex has the highest round-trip efficiency in the industry at 98% efficiency.

Also, this battery has several mounting options such as wall mount, floor mount and server rack mount to fit your individual project’s needs.

Product Information
Model eFlex 5.4
Series eFlex
Manufacturer Fortress Power
Type Lithium Iron Phosphate (LiFePO4)
Dimensions (L x W x H) 21.5″ x 17.5″ x 7.2″
Weight 108 lbs
Shipping Method Freight
Nominal Voltage 48V
Rated Capacity (20 Hour Rate) 105 AH
Terminal Type M8

Detailed Information

Lithium Iron Phosphate Battery

The Fortress Power eFlex is a 5.4 kWh scalable energy storage solution based on safe and energy dense prismatic Lithium-Iron-Phosphate cells. The high amperage, smart Battery Management System (BMS) includes relay disconnects, closed-loop inverter communication, cell voltage and temperature monitoring, and cell balancing to maximize reliability and longevity, as well as wifi for internet-of-things compatibility. The unit can be wall mounted, floor mounted, and server rack mounted.


  • 98% Roundtrip efficiency
  • High Durability and Long-Lasting
  • Safe Lithium Iron Phosphate Technology (LiFeP04)
  • Flexible mounting options
  • Remote monitoring
  • Advanced cell level monitoring and balancing
  • Close-loop communication with many hybrid inverters
  • Canbus, Modbus, and wifi communication
  • UL 9540 certified




Documentation – Sol-Ark 12k

Documentation – Fortress eFLEX 5.4