WattCycle Unveils Record-Breaking 10 kWh Balcony Solar Battery with 5 kW Bidirectional Output

Shenzhen Washi Energy Co., Ltd., operating under the WattCycle brand, has announced a new all-in-one balcony solar storage system featuring a 10 kWh capacity and 5 kW bidirectional power output. Debuting ahead of Intersolar Europe 2026, the unit aims to set a new performance benchmark for the compact plug-in residential segment, which has historically been limited to smaller storage and discharge capacities. This development allows European households to better manage energy loads and potentially arbitrage dynamic electricity tariffs through enhanced grid export capabilities.

WattCycle’s new system, launched by Shenzhen Washi Energy Co., Ltd., offers a rated capacity of 10,240 Wh and is available in bidirectional power configurations of 2.5 kW and 5 kW. This specification combination represents a significant jump for the "Balkonkraftwerke" (balcony power plant) category, where battery options have typically been restricted to 1–5 kWh with modest discharge rates. The 5 kW bidirectional capability allows the unit to not only charge from solar or the grid but also discharge energy back into the household AC bus or the utility grid, providing a tool for navigating Europe’s increasingly common dynamic electricity tariffs.

The system utilizes an AC-coupled architecture with a three-port design, including a microinverter input, an AC output, and a bidirectional grid connection. While AC coupling involves conversion losses of 2–5% per step, it allows the battery to integrate seamlessly with existing balcony or rooftop microinverter setups without requiring major electrical modifications. The unit also features integrated MPPT (Maximum Power Point Tracking) technology to optimize charging across varying light conditions and an internal heating function designed to maintain battery performance in the cold climates of northern Europe.

WattCycle claims this is the first single-unit 5 kW and 10 kWh configuration in the compact balcony segment, positioning it against competitors like the Bluetti Balco 500, which peaks at 3.68 kW, and Hoymiles HiBattery systems that require multiple units to reach high storage levels. For the estimated 4 million European households already using balcony solar, this high-capacity unit expands the potential for energy independence and grid interaction. However, the company has not yet disclosed pricing for the unit, and independent security audits of the hardware have not yet been performed to verify the manufacturer's claims.