PV module manufacturers usually offer a long-term product- and performance warranty. When it comes to ensuring this level of long-term quality, ZSW offers valuable assistance with its extensive testing capabilities in the laboratory and in the field.

Investors, banks, manufacturers, project developers and assessors rely on reviews and assessments of the performance, long-term stability and operational reliability of PV modules, as carried out by independent test facilities. Especially when verifying the suitability of PV modules produced using specific technologies and manufacturers for deployment in large international projects (bankability), it is sensible to have the modules randomly sampled and tested by third party experts in order to minimise the risks for all involved parties. Damage assessments and expert statements regarding faulty PV modules are becoming increasingly important for successfully enforcing guarantee and warranty claims.


Roland Einhaus
+49 711 78 70-254
[Translate to Englisch:] Solab Logo

// PV module test laboratory Solab

The ZSW testing laboratory for PV modules Solab is offering such services. Usually, tests according to the norms IEC 61215 and IEC 61730 are conducted, e.g. measuring of STC power, low light behaviour, isolation under wet conditions or tests such as potential-induced degradation (PID) according to IEC 62804. In addition, dependent on module location, it can be useful to conduct accelerated ageing test such as damp heat (DHT), thermal cycle (TCT) or UV lighting and expand the duration of theses tests far beyond norm requirements.

Analyses and damage assessments for PV modules with damage issues like PID, microcracks, LID, performance degradation or delamination, chalking and cracks of back sheets are all part of our service portfolio for our customers. The fact that we do not conduct certifications of PV modules for module manufacturers is testimony to our independence as a testing laboratory.

// ZSW’s Widderstall solar test facility

In addition to laboratory tests, the operation and monitoring of PV modules in the field form indispensable parts of a comprehensive quality inspection. While the IEC standard requires only a few weeks of outdoor exposure, this test period should be at least six months or – even better – one full year. With its  outdoor-test facility in Widderstall, southern Germany, ZSW offers its customers a perfectly suitable, well-equipped testing platform.

Generator test rig on ZSW's outdoor test field
Quality of PV modules: Chalking of a back sheet
Chalking of a back sheet
Quality of PV modules: Identification of back sheets fraught with risks in a solar power plant
Identification of back sheets fraught with risks in a solar power plant

// Consulting

On-site inspections of solar power systems

PV systems often exhibit yield losses and faulty components. In such cases, ZSW Solab carries out an analysis of the performance data, an on-site inspection of the PV system, IR thermography and performance measurements. In the context of damaged back sheets which show chalking, cracks or delamination, a screening consisting of random checks with FTIR spectroscopy at the solar power plant is offered which aims at identifying beyond doubt back sheets fraught with risks.

For further information, see the documents available as downloads on the bottom of this page.

Factory inspections and yield forecasts

Another measure for quality control is an expertise of the production plant of a PV module manufacturer (“factory inspection”) which is also being offered by ZSW Solab.

Using experimentally measured parameters, ZSW has developed calculation models and methods to predict the expected energy yield for system operators and investors.  We provide advice on site assessments and system planning, and check the yield quality of the installed PV systems. For more information about our services, which also include advice on the module, system and production level, see "PV module test laboratory" and "Solar test facility" under the keyword "Services".

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