The Fimer REACT2-BATTERY 4 kWh is a high-voltage lithium battery made in Italy that sets a new standard for efficiency in home energy storage. As the REACT2 hybrid system’s dedicated storage module, it has a sleek, modular design that lets homeowners start with a small setup and add more as their energy needs grow. The REACT2-BATT is the best choice for both high-performance new builds and advanced solar retrofits because it has the highest depth of discharge on the market (95%) and can be used with both AC and DC.
Italian Engineering Meets Samsung Power
Samsung makes the high-quality cells that are at the heart of every Fimer REACT2 4 kWh battery. This partnership brings together Fimer’s precise Italian manufacturing with chemical stability that is second to none.
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Maximum Usability: Many competitors only let you use 80% or 90% of the battery, but this solar battery with a 95% depth of discharge gives you 3.8 kWh of usable energy for every 4 kWh module installed.
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Whisper-Quiet Operation: Designed with natural convection cooling, the REACT2-BATT operates without the noise of mechanical fans, making it ideal for utility rooms or garages.
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Built to Last: With a 5+5-year warranty and a design life optimized for the European climate, this unit is a long-term investment in your home’s resilience.
Proprietary Integration: Best battery for Fimer REACT2 hybrid inverter
The Fimer REACT2-BATTERY 4 kWh is not just a storage unit; it is the perfect physiological match for the REACT2-UNO hybrid inverter. It is widely regarded as the best battery for Fimer REACT2 hybrid inverter systems because it communicates natively with the inverter’s brain.
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High-Voltage Advantage: Operating in a range of 170V to 575V, this system provides up to 10% more energy than lower-voltage battery alternatives by reducing conversion losses.
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Smart Energy Management: Through the MyREACT mobile app, you can monitor and control energy flows in real-time, aligning your solar production with your household consumption patterns automatically.
Flexibility for the Modern Home
The REACT2 series is the most flexible option available, whether you’re putting in a new array or upgrading an old one. Because it has a high-efficiency AC and DC coupling, it can be added to almost any existing residential solar system without having to replace the inverter that is already there.
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Modular Expansion: This modular HV solar battery scalable to 12 kWh allows you to stack up to three 4 kWh modules per inverter. You can even add modules years after the initial installation as your energy demands increase.
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Backup Confidence: During a grid failure, the REACT2 system can provide up to 3kW of emergency power, keeping your essential lights, fridges, and communication devices running when you need them most.
Performance Comparison: Fimer REACT2-BATT vs Tesla Powerwall 2
In the 2026 market, many researchers compare the REACT2 to all-in-one units. In a Fimer REACT2-BATTERY 4 kWh vs. Tesla Powerwall 2 comparison, the Fimer system stands out for its modularity. While a Powerwall is a fixed 13.5 kWh block, the Fimer system allows you to pay only for the capacity you need (4, 8, or 12 kWh) and offers higher round-trip efficiency due to its native high-voltage DC architecture.
| Feature | Specification Details |
| Model | REACT2-BATT |
| Battery Type | Lithium-Ion (Samsung Cells) |
| Total Energy | 4.0 kWh |
| Usable Energy | 3.8 kWh (95% DoD) |
| Operating Voltage | 170 V – 575 V |
| Charge/Discharge Power | 1.6 kW / 2.0 kW (Per Module) |
| Dimensions (HxWxD) | 740 x 490 x 229 mm |
| Weight | 50 kg |
| Protection Rating | IP54 (Indoor Recommended) |
| Warranty | 10 Years (5 + 5 years) |
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