Key takeaways:
BC modules are moving into wider deployment, making reliability testing increasingly important
LONGi tested its Hi-MO 9 module under dynamic load, static pressure, and hail impact conditions
Design changes, such as a flush glass surface, aim to improve performance under harsh environmental conditions
Back contact (BC) modules are emerging as the next step in the technology roadmap after TOPCon. There are commercial modules available from several Chinese manufacturers, including tier-1 players such as AIKO and LONGi (see TOP SOLAR MODULES). Nevertheless, reliability testing of these modules is crucial as they become more common in the near future.
In its recent press release, LONGi presented various test methodologies it has carried out on its Hi-MO 9 module, branded as HydroClear. These tests were conducted in simulated real-world outdoor scenarios in Mohe, Heilongjiang, which is China’s northernmost city.
The Hi-MO 9 module is based on LONGi’s hybrid passivated back-contact technology 2.0 (HPBC 2.0), which uses its TaiRay wafers. The company incorporated certain designs into its HydroClear module to ensure it can withstand extreme weather conditions. It uses a short frame with no edge protrusions, so that it is flush with the front glass surface. This prevents dust or snow from accumulating at the lower edge of the module.
The company conducted multiple tests on the module, including dynamic mechanical load, heavy static mechanical load, and hail impact tests.
In the dynamic load test, LONGi simulated outdoor storm cycles using a robotic arm to apply a bidirectional cyclic load of ±1,000 Pa over more than 1,000 consecutive push-pull cycles. In the static mechanical load test, a constant pressure of 5,400 Pa, equivalent to 540 kg/m² of snow, was applied on the front side. Additionally, a wind suction of -2,400 Pa was applied on the rear side. In this case, the load was applied gradually and maintained at the maximum for 1 hour. This was carried out on both sides of the module for 3 cycles each. In the hail impact test, modules in the central region, edges, and corners were tested with ice balls measuring 25 mm in diameter and weighing 7.53 g hitting the modules perpendicularly at a speed of 83 km/h.
LONGi claims that its HydroClear module survived all these test conditions without glass breakage, microcracks, or grid fractures. The internal components and electrical connectivity remained intact after continuous fatigue and under extreme suction and pressure.
In addition to the above, LONGi also conducted a damp heat (DH) test for 1,000 hours at an unspecified high temperature, and claimed no internal corrosion, power loss, or insulation failure. The product datasheet highlights IEC, UL, and other certifications.
The Hi-MO 9 HydroClear module has a maximum power output of 670 W with 24.8% efficiency. It is constructed with 132 bifacial half-cells in a dual-glass configuration, with a bifaciality of 75±5%. The company offers a 99% power output warranty after the first year and 88.85% performance after a 30-year lifetime.
