Overall objective

The scope of Task 2 has concerned the information exchange about activities already in progress in the participants' national programmes. Technical and economic information on performance and long-term reliability are very important for an emerging technology such as PV. Task 2 aims to provide performance data for both general assessments of PV system technologies and improvements of system design and operation.

Task 2 officially started the current work programme in September 2004 for a period of three years, building on previous accomplishments in PV system performance analysis. Task 2 activities are organized into the following Subtasks:

• Subtask 1: International Database
  This is achieved through the development of the PV Performance Database, an international database containing information on the technical performance, reliability and costs of PV systems and subsystems located worldwide. The information is gathered and presented by means of standard data collection formats and definitions. The database user can select PV system data, present monitoring data and calculated results, and in addition export these data into spreadsheet programmes. A collection of such a variety of high quality operational data presents a unique tool for PV system performance analysis. The database is updated regularly, and can be downloaded from the website http://www.iea-pvps-task2.org.

• Subtask 5: Technical Assessments and Technology Trends of PV Systems
  Participants analyse and validate expertise and performance results from grid-connected (GCS), stand-alone (SAS) and PV-based hybrid systems. The aims of this subtask are to demonstrate up-to-date performance validation criteria for a qualitative ranking of PV grid-connected, stand-alone and PV-based hybrid systems. It will also identify high performance products, technologies and design methodology in order to foster the development of maximum conversion efficiency and optimum integration of PV.

• Subtask 6: PV System Cost over Time
  Task 2 will identify and evaluate the important elements, which are responsible for the life cycle economic performance of PV systems by investigating economic data for all key components of PV systems and by gathering information about real life costs of maintenance of PV systems.

Summary of Task 2 accomplishments for 2005

• Subtask 1: International Database
  The PV Performance Database was updated and the programme was released in June 2005 as a tool for planning, sizing and improving PV systems with respect to operational performance and reliability. The new Performance Database contains high quality data of 431 PV systems of different system technologies, located in 21 countries. The Performance Database programme (47 MB) is available on CD-ROM and can be downloaded from the Task website http://www.iea-pvps-task2.org. Task 2 focused on the dissemination and promotion of the Task 2 database. As a result, 3 185 database users from 90 different countries and a broad range of sectors are making best use of the Task 2 database for their applications in planning & consulting, education, production and research. In 2005, highest demand for the Performance Database came from the engineering sector and the private sector, followed by the education and industry sector (Figure 2).
  
  

• Subtask 5: Technical Assessments and Technology Trends of PV Systems
  
  • Long-term reliability of PV Systems
    Based on the extended Performance Database, long-term “performance continuity” of the PV systems was investigated using monitoring data of 26 PV systems operating over 75 years. Both, monitoring data including hourly values of in-plane irradiance, module temperature and energy output of inverter of 26 individual PV systems, as well as several years of maintenance and failure information were employed to extract “correct” data sets of PV systems (Figure 3). PV system performance was analysed and compared at identical climatic conditions such as in-plane irradiance and module temperature. As first results, it was found that many PV installations present a constant performance level over time, while a strong shift of performance ratio over time was found for some PV systems.

  • User's Awareness of PV System Performance
    Activity leader Japan (AIST and JET) conducted a survey on technical problems of PV systems and on the users' awareness for grid-connected and for stand-alone PV systems. In a first step, the survey addressed grid-connected PV systems and users of the residential programme in Japan in November 2004 (104 replies). Intermediate results of the questionnaire survey on Japanese systems were prepared and presented during the Task meetings. Differences between expected and actual energy yield seem to be one reason for a pessimistic view on the PV systems in general. In a second step, the questionnaire survey was extended to stand-alone systems (SAS) investigating the troubles of SAS and the users' perception of PV systems in Mongolia in July 2005 (359 replies). First results were presented during the PV Quality Workshop in September 2005. The questionnaire will be extended to grid-connected and SAS systems in different countries.

  • Performance Prediction
    The collaboration with IEA Solar Heating and Cooling programme's Task 36 was carried on and a description of the potential transfer criteria of PV monitoring system insolation data into existing insolation mapping databases was developed. The PVPS Task 2 database will thus be compliant with the user-oriented structure for assessing resource data developed by SHC Task 36 and this will enable the qualification of the PVPS Task 2 database. In reverse, the PVPS Task 2 database will help SHC Task 36:
    • To define measures of the quality of models deriving irradiances from satellite observation and procedures for comparison,
    • To develop methodology for benchmarking and testing models. In addition, an overview of the existing on-going activities in the field of performance prediction was presented at the Task 2 September meeting held in Hameln.

• Subtask 6: PV System Cost over Time
  The global Economic Survey aims at gathering information on plants, technical performance, maintenance and cost of as many PV systems as possible. The Internet-based survey tool was developed by Switzerland, tested (online) by Task 2 members and translated from English to German, Italian, Spanish, Japanese and French language. The Economic Survey was started during the European Photovoltaic Conference in Barcelona in June 2005 by making the data acquisition tool to function on the public website www.iea-pvps-task2.org. Task 2 presentations at the Barcelona conference, individual invitations as well as publications in newsletters and magazines were used to motivate and attract people to give their input to this Economic Survey. The Economic Database includes the capability to search, sort and export information towards a free excel environment and allows Task 2 members to analyze all collected economic data.

Summary of Task 2 activities planned for 2006

• Subtask 1: International Database
  
  • Performance Database on the Web
    In addition to the Performance Database programme, which needs to be installed locally on a personal computer, Task 2 has started to build up an online database for public Internet access, which will be beneficial to new and additional target groups. This online Performance Database will contain an extract from the original database and will be optimized for fast Internet access. Further structural changes and modifications are necessary in order to use this database on a standard Internet server. Suitable presentations of the database information and results will be developed to make this Performance Database more understandable for a larger target audience.

• Technical Assessments and Technology Trends of PV Systems
  
  • PV in the Built Environment
    Task 2 will review PV system cases from the Performance Database with respect to shading effects. Case studies on shading losses on the PV array will be filtered out of the extended Performance Database and the literature. Methods and tools to determine shading losses will be analyzed and validated. First recommendations how to minimise yield losses due to shading will be developed making use of existing simulation programmes. The usefulness of recommendations will be tested against typical cases of shading from the extended database, and better guidelines will be the deliverable where appropriate.

    

  • Long-term Reliability of PV Systems
    Further long-term monitoring data will be collected to gain quantified information and results on the systems' reliability and learning curves. The results of other failure detection algorithm (e.g. Failure Detection Routine of PVSAT) will be compared to the analysed performance & failure curves for different examples. The influence of the incidence angle of irradiance on the Performance Ratio (PR) will be investigated. Further analysis of failure diagnosis aims at a detailed failure statistics of PV systems which enables to determine the effect a single failure type on the PR. A draft report including case studies as well as general information on the operational performance and reliability of PV systems will be presented.

  • Performance Prediction
    The efforts on this activity will focus on two areas, the first being the evaluation of the performance of the solar irradiation estimation tools where satellite data prediction will be compared with ground based measurements from the PVPS task 2 database. Through the performance database, it will be possible to identify PV systems for which hourly values of the solar irradiation on the tilted array plane as well as those of the array output are available. The task will consist in comparing such values with the ones calculated from satellite data onto the tilted plane.
    The second part of this activity will focus on the PV array performance prediction. For this part, the array output data from the database will be compared to that using satellite data and PV array performance models.

• Subtask 6: PV System Cost over Time
  During 2006 Task 2 will start to analyse the available information/ data in the PV System Cost over Time database. The number of reported systems (171 in 16 countries) will have to be enlarged, whereas the data update capability of the locally installed (PV System Cost over Time) databases by the task members will be useful. The algorithm to understand and analyze the date will be developed in parallel to the ongoing data collecting process. First results shall be available by the end of 2006.

Industry involvement

Key deliverables (2005 and planned)

• “Performance of PV Systems: Results from the IEA PVPS Projekt“ (in German), Austrian Energy Economic Forum, Vienna, Austria, February 2005.
• “Performance of Grid-connected PV Systems: Overview of PVPS Task 2“. In: 20th European Photovoltaic Solar Energy Conference, Barcelona, Spain, June 2005
• “Task 2 Achievements on Performance, Reliability and Analysis of PV Systems”, Solar Energy Society of Canada Inc. (SESCI) Conference 2005, Vancouver, Canada, August 2005.
• “PV System Performance Analysis”, Solar Power 2005 Conference, Washington DC, USA, October 2005.
• „Quality for Photovoltaic Systems - Proceedings of Task 2 /Industry Workshop“, ISFH, Hameln/Emmerthal, Germany, September 2005
• “Long-term Experiences of PV Systems“, Workshop PV Module Technology (in German), TÜV Rheinland Group, Cologne, Germany, December 2005
• PVPS Task 2 Performance Database programme update with collected data from 431 PV systems, released in June 2005.

Participants

Meeting schedule (2005 and planned 2006)

• The 2nd Task 2 Participants' Meeting was held in Cocoa, Florida, USA, 28 February - 02 March 2005.
• The 3rd Task 2 Participants' Meeting was held in Hameln, Germany, 26-28 September 2005.
• The 4th Task 2 Participants' Meeting will be held in Vancouver, Canada, 27-28 March 2006 as a Joint PVPS Task meeting.
• The 5th Task 2 Participants' Meeting will be held in Vienna, Austria, September 2006