WCA January 2012

It is especially designed for outdoor use, which means direct sun radiation and air humidity, but due to the halogen free flame retardant cross-linked jacket material the cable can also be installed in dry and humid conditions indoors. A product life cycle of 25 years can be expected for this solar cable. Insulation and jacket are easily removable. All materials used in the cable are in conformance to European RoHS-directive. There are two versions available signed by ink-jet printing for positive and negative polarity. The dimension range is from 2.5mm 2 (overall diameter 4.5mm) up to 35mm 2 (overall diameter 11.0mm), other cross sections are available upon request. The described solar cable is named Lütze Thermoflex Solar XPE. It has passed all the described tests and was certified by the VDE testing and certification institute according to the discussed specification [2] . It is registered at VDE by Reg-No 8293. Another solar cable type using AWG conductor sizes has been developed according to UL 4703 [3] and is currently/actually in the certification process. 7 Conclusions There are different standards for solar cables in different countries. The requirements are very high, but they differ due to the various national philosophies in respect to safety and reliability issues as well as market and subvention aspects. The determining factors in this application are external conditions, which do not depend on national laws and can depend only on local aspects. Therefore, a standard in the future will be established by international market acceptance.

❍ ❍ Figure 5 : The developed cable in different cross-sections

The main focus of UL 4703 is the fire performance. Tests to be performed are the Vertical Flame Test acc. to UL 1581, Section 1060 or optional flame test VW-1 acc. to UL 1581, Section 1080. Based on RHW-2 the flame test FT-2 acc. to UL 1581, Section 1100 is also required. Table 2 compares some important parameters and tests of both standards against each other. Therefore, another cable construction will be necessary to meet the UL-requirements.

6 Product Properties The newly developed solar cable is a single core cable built with a tinned stranded conductor. All materials are halogen free, flame resistant and fire retardant. No corrosive gases will be released in case of fire and the smoke density is low. The insulation and jacket materials are extremely resistant to weathering, UV-radiation and abrasion. The wide temperature range from -50°C to +150°C (fixed installation) enables the use of this cable in extreme weather conditions. Additionally, it is salt water resistant and resistant to acids and alkaline solutions. The cable is flexible and designed for high mechanical loads. So it is suitable for fixed installation as well as for moving applications without tensile load.

❍ ❍ Figure 4 : Long term thermal test results

Arrhenius Lutze Thermoflex Solar

Hours

Temperature in ºC

69

Wire & Cable ASIA – September/October 2007 Wire & Cable ASIA – January/February 12