Solar Systems – the weak links

Marc Pickering – Huber+Suhner Australia
May 2010

Due to some sensible government legislation that allows a better than even return per kW for solar systems connected to the grid, the return on investment for solar systems makes much more sense and now with the advent of a substantial increase in the wholesale cost of electricity in NSW the decision to implement a solar system on a home or business rooftop is easier to come to grips with.
The solar market in Australia is beginning to gain real traction, pay-back periods are considerably reduced and government incentives are still there however in any market where the demand is close to or greater than the availability of sub-components, designers, system integrators and installers look to alternative sources. Currently the solar market in Australia and worldwide is in such a growth mode that at times there can be a shortage of parts like silicon wafers to make solar panels or inverters which convert the DC current generated by the solar system to alternating current for insertion back into the grid.
Component shortages mean that systems cannot be built to the time specification desired of the client. Similarly when alternative or lower cost components are incorporated and these are sometimes not market proven over a long period the implementer takes on risk which is generally transferred to the end user unless a significant warranty is placed on the system in terms of a guarantee.
The Clean Energy Council of Australia (CEC) is the overseer of the alternative energy markets however they have not developed a standard for the design of solar systems like Europe has, which goes down to each and every component of a system.
Many component manufacturers have two product lines, one of high quality and higher cost which complies with the stringent TuV European standard and another more generic brand which is lower in cost.
In Australia the CEC will allow most products to be sold into the solar market that meet minimal testing criteria therefore our market is flooded with inferior generic brands. In addition those manufacturers who because of product quality cannot sell into the European and US markets see Australia as the ideal location to off-load components.

So what is the weakest link?

The answer to this question is three fold:
• Cables
• Connectors
• The junction box on the rear of solar panels

The European experience has shown that for a system to last the expected lifetime of 25 years, PVC and rubber cables, in addition to connectors which are not moisture proof will ultimately prove the weak link.

In Australia you can still find installers using non compliant rubber and PVC cables including twin TPS cables like those used in the electrical building industry that are not suited for high temperature applications or continued exposure to UV such as in a solar PV system. These cables would never be approved for use in the much less hostile European environment.

Life Expectancy of Insulation Materials

Temperature RADOX® Solar XLPE / Rubber PVC
120°C 20,000 hours 2,500 hours 625 hours
90°C 160,000 hours 20,000 hours 5,000 hours
70°C 640,000 hours 80,000 hours 20,000 hours


RADOX® Solar cables:
• have the highest mechanical robustness
• have the longest expected lifetime
• are approved for use in solar systems worldwide
• have a small outer diameter
• do not melt and are heat resistance
• do not shrink and have no cold flow
• have true copper concentricity
RADOX® Solar cables have proven high performance over 25 years and have become the bench mark in the solar industry.

Installers in Australia are increasingly recognising that they need to change former habits and are adapting the recognised benefits of the HUBER+SUHNER solar cable and twist lock solar connector even at a higher cost; they feel that this is an important factor to maintain the integrity of the solar system they guarantee and the reputation of their business.

Nevertheless, some installers will opt for lower cost generic connectors and even connectors that are not supposed to be used in an outdoor application. Some don’t see the solar array as an outdoor environment since the connecting cables are generally covered by the solar panels, however this is a recipe for disaster and the consequences will be seen after a few heavy downpours combined with the sun to cause humidity that will penetrate through the connector. Humidity and loosely fitted connectors will be an ultimate launch pad for future electrical problems.

PV solar cables and connectors are important components in a solar installation. They provide the electrical interconnections between the module and the power inverters. They contribute significantly to the high performance and long service life of such installations. High life expectation, adverse environmental influences and wide temperature and humidity fluctuations place rigorous demands on the design, materials and workmanship of cable assemblies.