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Sol-Ark 12kW and Fortress Power 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 InverterQnty. 1
Fortress Power 5.4kWh eFlex Lithium Iron Phosphate BatteryQnty. 3
Fortress Power Battery Wall Mount EnclosureQnty. 3
FW1000 DC EnclosureQnty. 1
Sets of 4/0 Battery to Inverter Red and Black CablesQnty. 3


PV Recommendation Size for Pre-wired Systems

Sol-Ark 12K Generator - InverterClick here to see Suggested PV String Guide

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 Capacity6,500W+6,500W = 13,000W
Max PV power delivered to Battery & AC outputs12,000 Watts
Max DC voltage500V@18A, 450V@20A
MPPT voltage range150-425V
MPPT Starting Voltage175V
Number of MPPT2
Nominal AC Output Voltage120/240/208V split phase
Peak Inverter Efficiency97.5%
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 TypeLead-Acid or Li-Ion
Nominal DC Input48V
Capacity50 – 9900Ah
Grid to Battery Charging Efficiency96.0%
Dimensions (H x W x D)30.0” x 18.30” x 10.00”
Weight78 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.

ModeleFlex 5.4
ManufacturerFortress Power


TypeLithium Iron Phosphate (LiFePO4)
Dimensions (L x W x H)21.5" x 17.5" x 7.2"
Weight108 lbs
Shipping MethodFreight
Nominal Voltage48V