Fault Analysis for Solar Electric Installations

Systematic fault analysis


Cölbe, June 2011.
Quality assurance and effective fault analysis approaches increasingly gain importance

„A solar electric plant delivers clean electricity for at least 20 years. Therefore product quality, professional installation and the long term reliability of contact persons are enormously important!“ explained Christof Biba, member of the Board of Wagner & Co. For both, private customers as well as professional installers, quality assurance and effective fault analysis approaches increasingly gain importance. During the solar boom of the recent years a certain percentage of installations have been set up that show a significant power degradation over the years, posing a dilemma for some installers: the complaint cannot be technically confirmed, and the customer is angered and dissatisfied because the installer cannot detect any faults during the on-site analysis. Costly panel diagnosis and dismantling are possible outcomes.

Such scenarios for installer and private customer can already be avoided prior to the installation by entrusting a qualified installer and using high quality components. Here Wagner & Co as complete systems supplier and distributor sees additional need to act, in order to provide sufficient after-sales support for installers and private customers. The company has been concerned with PV testing methods for many years. In October 2010 70 technicians and engineers from across Germany traveled to the company headquarter in Coelbe for the first ever solar-electricity diagnostics forum: Which testing equipment is currently available and which possibilities for fault analysis do they offer? When it comes to this topic, experience is invaluable in order to distinguish normal and fault indicating test results. These experiences were shared among the participants. To date no testing device exists that simply can be attached to a panel field and then displays system errors in a clear and simple manner. However, a systematic approach can greatly simplify the diagnostics procedure. Michael Beer, veteran developer and practitioner at Wagner & Co: „To quickly find the causes of faults is a great challenge. The current testing devices are complex and also susceptible to external variables such as unsteady environmental factors such as irradiation or temperature. We therefore developed an error matrix for the systematic detection of faults.

The systematic fault analysis approach encompasses three steps:

1) The foundation for every fault analysis is a well prepared start-up report. It requires a good quality multimeter, DC current detector, a pyranometer and an insulation resistance tester with a testing range of up to 1000 V. Later the start-up record serves as the main reference for follow up tests. The records also serve as a solid argument for the installer, if these follow up results do not significantly divert from the original test results. When later test results do divert from the original start up data, the first step is a visual inspection, for example of the string. According to Michael Beer a large number of faults already can be discovered by visual inspections, and only a smaller portion is found by measurements. If no fault can be found, the next step follows.

2) Before beginning with the 2nd step, the cost coverage should be clarified, since costs in the four digit range might easily accrue. Now photovoltaic I-V curve analyzers and infrared cameras are utilized. The curve analysis is time consuming, and the infrared imaging has to be carried out from a perpendicular position, so usually at least a crane or hoist is required.

To address these complications, Wagner & Co has developed a specialized and already patented measuring tool that will allow for a time resolved analysis of all parameters relevant for the system performance.

3) If all other causes can be ruled out, the final cause of low system performance was narrowed down to panel failures. In this case the modules have to be dismantled for testing in a certified photovoltaic testing laboratory with a standardized testing environment.

„As a corporation we feel that we have a responsibility to share our experience and know-how with our customers“, says Christof Biba. „From the planning and sizing phase onwards we stand by our partners and train them technically, so that errors can be avoided. We will continue to expand our service offers in this area.“

In 2011 the Wagner Academy will offer additional PV diagnostics seminars in Cölbe, and a forum for the interested lay public is also planned.

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Wagner & Co Solartechnik GmbH
Sandra Christiansen
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D-35091 Coelbe