Helping harness solar power
IEC Technical Committee works on solar photovoltaic energy systems
As solar power is set to occupy a growing share of the future global energy mix, PV (photovoltaic) energy generation has been expanding dramatically in recent years. IEC TC (Technical Committee) 82: Solar photovoltaic energy systems, prepares International Standards that play a central role in the development of PV technology and that contribute to cost reduction and innovation and to safer, better and more efficient PV systems.
Huge and growing market
IEC TC 82 was established in 1981; it has five WGs (Working Groups) and one JWG (Joint Working Group). Participants from 46 National Committees are represented in this TC, which has published more than 55 International Standards since its creation. Its chairman, Heinz Ossenbrink, gave a comprehensive overview of the global PV market and of the TC’s contribution to its expansion in a presentation to the IEC’s SMB (Standardization Management Board) in February 2011.
The international PV market has been growing at an astonishing rate with sales of PV modules increasing at a CAGR (Compound Annual Growth Rate) of 40 % between 1981 and 2010. It is expected to grow by an additional 30 % CAGR until 2020, Ossenbrink said. This sector had a turnover in excess of USD 27 billion from the sale of PV modules alone in 2010.
The international PV market is characterized by a mixed production and deployment structure with Asia, China in particular, producing 72 % of the PV modules and systems, and Europe having most (76 %) of the grid-connected installations. Asia is set to become a major growth area for the number of systems installed. Japanese Prime Minister Naoto Kan pledged to cut the cost of solar generation power in the country by 20 % by 2020 and to place solar modules on 10 million homes across Japan by 2030.
Ossenbrink identified the major growth areas for PV in the future as the utility grid for peak demand, the rooftops of residential and non-residential buildings, and rural electrification.
Challenges facing the PV industry concern the lifetime energy production of systems and their rates of ROI (return on investment), extending the lifetime of modules beyond 30 years, safety (fire risks) and environmental standards (recycling and clean energy).
Needs are anticipated in a number of areas that include the construction of large utility plants and concentrator systems, inverters – required to change the DC (direct current) electricity from PV systems into AC (alternating current) for use with home appliances or feed into a utility grid – and interfaces, to name just a few.
All these and new PV technologies will mean more work for TC 82. Measuring the performance of PV modules and ensuring their safe operation are just two areas in which TC 82 prepares International Standards.
Measuring PV energy performance
With new PV technologies being introduced all the time, a growing number of manufacturers offer many products incorporating PV modules. Besides long-established solar modules, these include BAPV (building-attached PV), BIPV (building-integrated PV) and solar windows, also known as PVGUs (PV glass units). With this ever-expanding offer, it is getting essential for users and manufacturers to know which PV modules offer the higher energy yield over a long period.
PV modules power performance is currently rated in peak Watts measured under STC (Standard Test Conditions): solar irradiance of 1 kW/m², air mass 1.5 and a PV cell temperature of 25°C.
Accurate ratings are important as the maximum power value also is used as the price reference for PV modules, a particularly significant factor to assess ROI when feeding power from PV systems into grids, as investors are paid for the actual power delivered.
However, the current measurement methodology based on STC does not take into account the impact of different climatic, seasonal or environmental conditions on the performance of PV modules, which varies in any case with the technology used.
To achieve more comprehensive and accurate measurements, IEC TC 82 has been working on the 61853 series of International Standards for evaluating PV module performance over a range of irradiances, temperatures and time periods spread over the year. It released the first of these International Standards, IEC 61853-1, Photovoltaic (PV) module performance testing and energy rating – Part 1: Irradiance and temperature performance measurements and power rating, in January 2011.
This series will give users and manufacturers much needed and more precise ratings of the performance of PV modules under different conditions than those available using the current method. The accuracy achieved with the 61853 standards will prove essential to guide module selection for given locations and conditions.
TC 82 published IEC 62109-1, Safety of power converters for use in photovoltaic power systems – Part 1: General requirements, in April 2010.
The purpose of this standard is to define the minimum requirements for the design and manufacture of PCE (power conversion equipment) used in PV systems for protection against electric shock, energy, fire, mechanical and other hazards. It provides general requirements applicable to all types of PCE.
TC 82 soon plans to release Part 2: Particular requirements for inverters and may publish additional parts as new products and technologies are commercialized.
Both series of International Standards are examples of the kind of the essential work carried out by TC 82, which has allowed the PV sector to grow at such an impressive rate since its creation and which will enable it to occupy a larger share of the future global energy production.