Friday 14, September 2007

MULTI-CONTACT QUESTIONS EVALUATION OF SOLAR CONNECTORS.

It was gratifying to observe that Photon has singled out solar plugs, which lead an inconspicuous existence, as a topic for a detailed study. This is particularly the case because characteristics of these elements which are important for safety are often underestimated or simply ignored.

It is regrettable that the reported examinations, tests and evaluations do not cover most of the relevant criteria and that some characteristics are not assessed in a balanced manner. With regard to the safety characteristics Photon concentrated primarily on pulling-out forces, but in this connection no comparison can be made between forces measured at a constant, relatively low withdrawal speed and the jerking force which is applied to connector when a person trips over a lead. Tripping over the lead is mentioned by way of a practical comparison, but no measurement of the forces involved was carried out, and likewise no practical test. Furthermore, no meaningful safety evaluation can result from an assessment of this characteristic made only with a single cross-section of a lead type, only in a new condition and under laboratory conditions. If one takes into consideration all these points which are of practical relevance, the result of the evaluation looks completely different.

An important safety characteristic of solar plug connections is their long-term stability, which was not considered at all. Solar installations are expected to have a life of several decades. The effects of weather and temperature can seriously affect their insulation and contact properties, and rising contact transmission resistances and the ageing of insulating materials can result in failures and consequential damage.

Other important safety aspects include suitability for the construction site, i.e. the robustness of components, possible operating and assembly errors, the simple verification of correct engagement and other points which are described in our evaluation of PV connectors. The report makes no mention whatsoever of such points. Only a few of the tested products fulfil all the UL, IEC and VDE safety standards which are now recognized and applied throughout the world. A comparison of the Photon criteria with these standards casts severe doubts on their validity.

For all the above reasons, we do not consider the evaluation of solar plug connectors by Photon to constitute a meaningful assessment.

Markus Kohler
Product Manager Photovoltaic Multi-Contact AG, Allschwil Schweiz