The worldwide expansion of photovoltaic (PV) installations is also giving rise to new areas of application in challenging environmental conditions. About 35 % of the Earth’s land surface is covered by deserts, leading to a push for efficient uses of these otherwise unpopulated areas with little economic potential – like the installation of PV solar power plants in hot, dry deserts in South America, Africa, southern Europe and the Middle East.
Requirements for operating electrical installations in ambient temperatures over 70 °C or at altitudes higher than 2000 m differ from the requirements for standard installations due to the different climate conditions. Yet, it is precisely in areas with such harsh conditions, like deserts and high mountain ranges, that offer large spaces and optimal solar radiation for efficient photovoltaic systems. The original Stäubli MC4 connector portfolio has a proven track record for such kind of applications.
As a result of this market development, the Technical Committee TC82 of the International Electrotechnical Commission (IEC) will more carefully distinguish the requirements for different ambient temperature ranges and prepare the new edition of safety standards for PV modules, IEC 61730-1, for applications at operating temperatures of up to 70°C (98th percentile - for 98 out of 100 applications). For applications at higher operating temperatures, such as installations in desert regions, the specifications of IEC TS 63126 will apply.
IEC TS 63126 identifies thermal requirements not only for PV modules, but also for added components like PV junction boxes or PV connectors, for two different temperature levels. The two categories for these modules are:
Temperature Level 1: greater than or equal to 80°C (T98th - in 98 out of 100 cases)
Temperature Level 2: greater than or equal to 90°C (T98th).
Section 6.3 of this technical specification lists the requirements for PV connectors according to IEC 62852 for use at the module temperature levels described above. The connectors’ upper limiting temperatures (ULT) are required to have the following minimum values:
ULT for connectors used for installation of Level 1 PV modules: at least 95°C
ULT for connectors used for installation of Level 2 PV modules: at least 105°C
The requirements for insulation coordination in the safety standards for electrical products are usually designed for applications at altitudes up to 2000 m (Elevation above sea level). For applications at higher elevations, the requirements for clearances must be corrected because the lower air pressure reduces the electrical installations’ resistance to voltage flashover across the clearance. Therefore, the minimum clearance must be multiplied by a correction factor from Table A.2 of IEC 60664-1:2020 or verified with a correspondingly higher test surge voltage.
For over 25 years, Stäubli connector systems for DC photovoltaic applications have been known for their high contact quality and durability. Now, Original MC4 products from Stäubli are the first PV connectors to meet the requirements for installations in PV systems with module temperature level 2 according to the TÜV Rheinland test procedure. This means that Stäubli PV connectors have been successfully tested for PV installations in climate conditions up to at least 105 °C.
TÜV Rheinland has also verified the suitability of the Original MC4 products for use at elevations of up to at least 5000 m above sea level.