PV Tech Power Papers

Operations and maintenance | The distribution and growing size of PV fleets mean new approaches to plant operation and maintenance are needed. Florian Danner, Jens Kahnert and Bjarn Röse of Conergy Services outline the key ingredients for cost-effective O&M in a globalised industry.

On-site testing | PV project owners are becoming increasingly conscious of the need to understand how their plants are performing in the field. Ben Willis explores how mobile testing units are emerging as an important tool in the early detection of faulty module equipment.

Defect assessment | DuPont Photovoltaic Solutions recently completed a five-year study of commercial crystalline silicon PV systems, amassing a wealth of new information about PV system field experience and PV module defects. Principal investigator Alexander Bradley discusses the findings, which, in addition to supporting the company’s ongoing analysis of materials performance, are expected to provide benefits across the industry. Building on the industry knowledge pool contributes towards the standardisation of performance expectations across the solar industry, enables the development of more stringent risk mitigation techniques, and helps purchasers of solar power systems make educated and informed materials assessments.

Power loss | The highly accurate module efficiency certified by accredited laboratories right after module production is at odds with the very rough estimate of the module’s long-term efficiency stated by the manufacturer for its expected lifetime, through a commonly accepted and industry-standard power warranty. Agustin Carretero of skytron energy presents an innovative method for calculating module degradation by using string-monitoring systems, and compares the results obtained for a case study with the module manufacturer’s power warranty statement.

Module performance | The potential for PV modules to fail before the end of their intended service life increases the perceived risk, and therefore the cost, of funding PV installations. While current IEC and UL certification testing standards for PV modules have helped to reduce the risk of early field (infant mortality) failures, they are by themselves insufficient for determining PV module service life. In this paper, teams from Fraunhofer CSE and Fraunhofer ISE present the results of the Fraunhofer PV Durability Initiative’s third round of testing, which now includes 10 module types.

Power oscillation | In the last few years the power rating of PV power plants has risen very quickly to values reaching several hundred megawatts. This means there are hundreds, or even thousands, of inverters operating in parallel in these plants. Furthermore, these large-scale PV power plants are often built far away from cities and are therefore connected to the grid via long transmission lines. This leads to weak grid conditions in the power plants, and these conditions give rise to the risk of electrical instabilities within the plant, or instabilities of the plant within the grid. Roland Singer of Fraunhofer ISE explains how these electrical instabilities can be detected and counteracted.

PV panel reflction | The increasing deployment of PV systems in dense urban areas has drawn attention to the issue of glare and the public discomfort arising from the sun’s reflection on the PV panels. Licheng Liu, Yong Sheng Khoo and Thomas Reindl of the Solar Energy Research Institute of Singapore (SERIS) and Julius Tan of Sunseap Energy discuss ways of fine-tuning system designs and alleviating visual discomfort, while not compromising on the energy yield of PV systems.

BIPV | Building-integrated PV has yet to live up to its promise, remaining a niche sector of the solar industry. However, as Silke Krawietz writes, European and international climate and energy goals, and a chance of reviving the European PV manufacturing industry, all offer BIPV the opportunity of becoming a mainstream technology.

Commercial rooftops | Innovations in commercial rooftop PV mounting systems are offering new possibilities for installers as they seek to drive down costs. Andy Colthorpe looks at some of the key developments that are helping breathe life into a segment that has so far been slow to take off.

Trackers | The economic argument for trackers is increasingly compelling. Matt Kisber, president and CEO of Silicon Ranch Corporation explains why the technology’s use is increasing and examines the benefits of opting for single axis tracking systems.