Addressing Europe’s growing demand for energy storage systems (ESS) and supporting a round-the-clock (RTC) power supply, Hoymiles promoted its latest product lineup during Intersolar Europe 2025. The Chinese inverter and ESS maker’s booth displayed ESS products, targeting commercial and industrial (C&I) and utility applications.
Product Description
DC Side
The company displayed its HoyUltra 2 series HESS-261-2h ESS model for the C&I segment. Designed for AC-coupled ESS configurations, its 1,030 × 2,450 × 1,400 mm (W × H × D) sized panel is combined with vertical battery stacks and a power conversion system (PCS). Equipped with 5 battery packs, each rated for up to 52.25 kWh and connected in series, this system boasts a total energy storage capacity of up to 261 kWh. Each battery pack comprises 52 series-connected 3.2 V, 314 Ah lithium iron phosphate (LFP) battery cells. Based on this system configuration, it has a nominal rated charge and discharge rate of 0.5 P with a round-trip efficiency (RTE) of more than 88.4%. In addition, its maximum rated RTE is 90.3%, while the corresponding charging and discharging rates have not been specified by the company. All these indicate that this system can efficiently absorb or deliver up to 261 kWh of energy over an unspecified cycle.
Contrasting to the former’s single panel configuration, the utility-scale ESS system - HoyPrime series HP02CUBE – is housed in a container, measuring 6,058 × 2,896 × 2,438 (L × W × H). It consists of similar types of battery cells like its C&I counterpart; however, it has a system configuration of 6P384S. While the company does not disclose the details about its battery stacks, the 6P384S configuration indicates 6 battery strings, each with 384 series-connected battery cells, connected in parallel. This results in a stored energy of up to 2.064 MWh under a rated DC system voltage of 1,228.8 V. Supporting grid operation at a MW scale, the company states this ESS is designed to absorb or discharge up to 840 A at a rate of 0.5 P not exceeding 8,000 cycles.
AC Side
The HoyUltra 2 operates in 2 modes – on-grid and off-grid. In on-grid mode, this system is rated to deliver up to 125 kW 3-phase AC power to C&I consumers. In case of a grid outage or failure, it switches to off-grid mode in which it can deliver up to 125 kW nominal 3-phase backup for 2 hours. However, it can handle 1.1 times the rated nominal load, or 137.5 kW, for a certain duration. In addition, it can provide 1.2 times the rated output capacity, or 150 kW, for less than 1 minute to support the inrush current of critical C&I loads, supporting uninterrupted operation.
Compared to the former’s 2 operating modes, the HoyPrime series operates only in on-grid mode. It can feed up to 1 MW of 3-phase AC power to the grid at a 690 V line voltage, which can be subsequently stepped up to support diverse grid-scale ancillary services. According to the company, paralleling multiple systems can enable up to a 100 MW level of grid support.
Safety
Both the displayed models are equipped with an ethylene glycol-based liquid cooling mechanism. This allows for full-capacity operation without any derating at up to 50°C for HoyUltra 2 and 45°C for the HoyPrime series. In terms of safety against fire, in addition to a sprinkler-based water firefighting system , the C&I and utility-scale ESS models have a Perfluorohexanone-based fire extinguisher.
