Guidelines to Quality Quality Assurance

The main Quality Assurance criteria that can be assessed and identified include:
  • Visual inspection
  • Qualifications and Certificates
  • Quality of Service
  • Other device quality parameters related to the inverter and performance monitoring system

Visual Inspection

Visual inspection of the condition of a PV module can reveal several quality issues which must be considered. In general, when inspecting a PV module before purchase we should verify that:
• The PV module is manufactured as a rigid non-permeable structure, sealed and well-constructed
• No visual cracks are observed in the cell surface
• The cells are interconnected in straight lines and that the interconnections follow industrially made well-oriented connections
• The cells are all of the same type and colouring
• The junction box is well attached to the back of the module
• The modules are from a new/recent production line

Qualifications and Certificates

Certification and adherence to international standards can ensure quality and reliability for PV modules. Quality marks and seals are important. Modules that comply and have been tested at certified institutions according to the requirements set by the following standards are expected to have long lifetime at high performance:

• IEC 61215: Crystalline silicon terrestrial photovoltaic (PV) modules – Design qualification and type approval
• IEC 61646: Thin-film terrestrial photovoltaic (PV) modules – Design qualification and type approval
• IEC 61730: Photovoltaic (PV) module safety qualification
• EN 50380: Datasheets and nameplate information for photovoltaic modules
In addition, many manufacturers provide information for additional tests assuring performance quality against several failures and degradation mechanisms such as:

• Anti Potential Induced Degradation (PID) products
• Protection against Hot Spots
• Ammonia resistance

Potential Induced Degradation (PID) resistance

PID is a new form of degradation caused by leakage currents triggered by high voltage installations and certain climate conditions. It can reduce the power of the module significantly hence it is important to select modules that have been tested for PID and are PID resistant.

Light Induced Degradation (LID) resistance

During the first months of operation most modules experience an initial degradation (power reduction) due to the light exposure. A good PV module will exhibit low or no LID.

Experience

The experience of the manufacturer and installer is an important aspect for a quality PV system. Experience includes both the length of time in the industry and also endorsements from previous customers.

Quality of Service

The quality of service offered by the manufacturer/installer is an important criterion which includes ease of contact, initial site survey, first impression of their service, previous customer endorsements and duration of replacement of modules or inverters.

Training of Technical staff

An important factor that directly affects the quality of the installation is the training of the installer.

Inverter

The inverter is an important component of the PV system as it is the electronic device that converts the DC produced power to AC. The main requirements in the selection of the inverter include:
• reliable operation at both high and low ambient temperature conditions
• high conversion efficiency (both Maximum > 96 % and European Efficiency > 95 %)
• automatic operation, visual display of energy yield and faults
• compliance with national codes.

Monitoring System

With the use of a Monitoring System the performance of a PV system can be ensured as these systems offer plant monitoring, performance display, detection of faults and alerting . A simple monitoring system can be offered by the inverter itself or can be extended with the use of an irradiance and temperature sensor in order to correlate the weather conditions to the performance of the PV system.