Testing of small sinusoidal-inverters for photovoltaic stand-alone systems

A test facility was developed and successfully put into operation, enabling the complete and accurate electrical characterisation of stand-alone inverters. This paper presents a description of the facility and the measurement method, as well as results from two new products of ASP, Laupen, Switzerland with 150 and 250 W(AC) output power and input voltages of 12 and 24 VDC, respectively. Both are sinusoidal-type inverters, producing grid-quality power, suitable for all applications. Maximum efficiencies of 89 and 90% were measured, indicating large improvement in performance during the last 15 years. Both efficiencies closely agree with the manufacturer's specification of 90 and 92%. The output voltage at nominal output power was 213 and 221 VAC, i.e. somewhat too low for the 12 VDC inverter. The standby losses were found to be 1.8 and 3.3 W, respectively. The latter is 32% higher than specified by the manufacturer. Improvements are suggested regarding the reduction of losses and the cooling of the transistors. The question as to whether pulsating current withdrawal from battery storage, caused by sinusoidal inverters, has a negative impact on the battery's lifetime, cannot be answered from the tests performed so far. The specific retail prices (excluding Value Added Tax, VAT) of the inverters tested are 1.1 and 0.84 Dollars per Watt output power for the 12 and 24 V inverter, showing a cost reduction of approximately a factor of two over the last 15 years. The results from randomly chosen inverters tested at PSI were approved by the Swiss Federal Inspectorate of Heavy Current.Inverter test set-up Measurement method Stand-alone inverters Electrical characterisation Efficiency Sinusoidal output voltage Standby losses Part-load efficiency

Efficiency and degradation of a copper indium diselenide photovoltaic module and yearly output at a sunny site in Jordan

The present work mainly deals with the testing and modeling of a commercially-available copper indium diselenide (CIS) ST40 module from the former Siemens Solar Industries (SSI). For this purpose, a large quantity of current/voltage characteristics were measured in the Paul Scherrer Institute (PSI)'s photovoltaic test-facility under different cell temperatures, solar irradiation and air mass, AM, conditions. They were used to develop a semi-empirical efficiency model to correlate all measured data sets. The goal was to make available a model, allowing quick and accurate calculation of the performance of the CIS module under all relevant operating conditions. For the undegraded state of the module, the efficiency model allowed us to deduce the efficiency at Standard Test Conditions, STC, and its temperature coefficient at STC, which were 11.58% and minus 0.050%/°C, respectively. The output of the undegraded module under STC was found to be 42.4 W, i.e., 6% higher than specified by the manufacturer (40 W). Furthermore, the efficiency does not decrease with increasing air mass. At a cell temperature of 25 °C and a relative air mass of 1.5, the module has a maximum in efficiency of 12.0% at an irradiance of about 650 W/m2. This indicates that the series-resistance losses become significant at higher irradiances. Hence, improving the transparent conducting oxide (TCO) electrode on the front side of the cells might lead to a higher output at high irradiances. Identical testing and modeling were repeated after having exposed the module to real weather conditions for one year. We found that the STC efficiency was reduced by 9.0%, from 11.58 down to 10.54%. The temperature coefficient of the efficiency had changed from minus 0.050 %/°C to minus 0.039%/°C. These results indicate possible chemical changes in the semiconductor film. The output of the module at STC was reduced by 9.0% from 42.4 W down to 38.6 W. Using meteorological data from a sunny site in the South of Jordan (Al Qauwairah) and the efficiency model presented here allows us to predict the yearly electricity yield of the CIS module in that area. Prior to degradation, the yield was found to be 362 kWh/m2 for the Sun-tracked module; and 265 kWh/m2 for the fix-installed module (South-oriented, at an inclination angle of 30°). After degradation the corresponding yields were found to be 334 and 241 kWh/m2; meaning losses of 8.4% and 9.5%, respectively. (Note: all units of energy, kWh, are referred to the active cell area.) Having available efficiency models for other module types, similar predictions of the yield can be made, facilitating the comparisons of the yearly yields of different module types at the same site. This in turn allows selecting the best module type for a particular site. © 2006 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex

Efficiency and degradation of a copper indium diselenide photovoltaic module and yearly output at a sunny site in Jordan

The present work mainly deals with the testing and modeling of a commercially-available copper indium diselenide (CIS) ST40 module from the former Siemens Solar Industries (SSI). For this purpose, a large quantity of current/voltage characteristics were measured in the Paul Scherrer Institute (PSI)'s photovoltaic test-facility under different cell temperatures, solar irradiation and air mass, AM, conditions. They were used to develop a semi-empirical efficiency model to correlate all measured data sets. The goal was to make available a model, allowing quick and accurate calculation of the performance of the CIS module under all relevant operating conditions. For the undegraded state of the module, the efficiency model allowed us to deduce the efficiency at Standard Test Conditions, STC, and its temperature coefficient at STC, which were 11.58% and minus 0.050%/°C, respectively. The output of the undegraded module under STC was found to be 42.4 W, i.e., 6% higher than specified by the manufacturer (40 W). Furthermore, the efficiency does not decrease with increasing air mass. At a cell temperature of 25 °C and a relative air mass of 1.5, the module has a maximum in efficiency of 12.0% at an irradiance of about 650 W/m2. This indicates that the series-resistance losses become significant at higher irradiances. Hence, improving the transparent conducting oxide (TCO) electrode on the front side of the cells might lead to a higher output at high irradiances. Identical testing and modeling were repeated after having exposed the module to real weather conditions for one year. We found that the STC efficiency was reduced by 9.0%, from 11.58 down to 10.54%. The temperature coefficient of the efficiency had changed from minus 0.050 %/°C to minus 0.039%/°C. These results indicate possible chemical changes in the semiconductor film. The output of the module at STC was reduced by 9.0% from 42.4 W down to 38.6 W. Using meteorological data from a sunny site in the South of Jordan (Al Qauwairah) and the efficiency model presented here allows us to predict the yearly electricity yield of the CIS module in that area. Prior to degradation, the yield was found to be 362 kWh/m2 for the Sun-tracked module; and 265 kWh/m2 for the fix-installed module (South-oriented, at an inclination angle of 30°). After degradation the corresponding yields were found to be 334 and 241 kWh/m2; meaning losses of 8.4% and 9.5%, respectively. (Note: all units of energy, kWh, are referred to the active cell area.) Having available efficiency models for other module types, similar predictions of the yield can be made, facilitating the comparisons of the yearly yields of different module types at the same site. This in turn allows selecting the best module type for a particular site. © 2006 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex

Efficiency and degradation of a copper indium diselenide photovoltaic module and yearly output at a sunny site in Jordan

The present work mainly deals with the testing and modeling of a commercially-available copper indium diselenide (CIS) ST40 module from the former Siemens Solar Industries (SSI). For this purpose, a large quantity of current/voltage characteristics were measured in the Paul Scherrer Institute (PSI)'s photovoltaic test-facility under different cell temperatures, solar irradiation and air mass, AM, conditions. They were used to develop a semi-empirical efficiency model to correlate all measured data sets. The goal was to make available a model, allowing quick and accurate calculation of the performance of the CIS module under all relevant operating conditions. For the undegraded state of the module, the efficiency model allowed us to deduce the efficiency at Standard Test Conditions, STC, and its temperature coefficient at STC, which were 11.58% and minus 0.050%/°C, respectively. The output of the undegraded module under STC was found to be 42.4 W, i.e., 6% higher than specified by the manufacturer (40 W). Furthermore, the efficiency does not decrease with increasing air mass. At a cell temperature of 25 °C and a relative air mass of 1.5, the module has a maximum in efficiency of 12.0% at an irradiance of about 650 W/m2. This indicates that the series-resistance losses become significant at higher irradiances. Hence, improving the transparent conducting oxide (TCO) electrode on the front side of the cells might lead to a higher output at high irradiances. Identical testing and modeling were repeated after having exposed the module to real weather conditions for one year. We found that the STC efficiency was reduced by 9.0%, from 11.58 down to 10.54%. The temperature coefficient of the efficiency had changed from minus 0.050 %/°C to minus 0.039%/°C. These results indicate possible chemical changes in the semiconductor film. The output of the module at STC was reduced by 9.0% from 42.4 W down to 38.6 W. Using meteorological data from a sunny site in the South of Jordan (Al Qauwairah) and the efficiency model presented here allows us to predict the yearly electricity yield of the CIS module in that area. Prior to degradation, the yield was found to be 362 kWh/m2 for the Sun-tracked module; and 265 kWh/m2 for the fix-installed module (South-oriented, at an inclination angle of 30°). After degradation the corresponding yields were found to be 334 and 241 kWh/m2; meaning losses of 8.4% and 9.5%, respectively. (Note: all units of energy, kWh, are referred to the active cell area.) Having available efficiency models for other module types, similar predictions of the yield can be made, facilitating the comparisons of the yearly yields of different module types at the same site. This in turn allows selecting the best module type for a particular site.Copper indium diselenide (CIS) module Current/voltage(IV)-characteristic efficiency model Energy yield Degradation

Solar irradiation measurements in Jordan and comparisons with Californian and Alpine data

In order to obtain reliable irradiation data for the design, operation and economic assessment of solar power stations, a measurement campaign has been performed in Jordan. As promising sites the desert near Quwairah in the South of Jordan, the stony desert South East of Amman and the elevated plateau near Naqb and also in the South of Jordan were chosen. Measurements were performed during the period of June 1989 to July 1992. The data were evaluated and compared with data of Barstow, California and the Swiss Alps. From the yearly sums of the direct normal irradiation in 1990 and 1991 at Quwairah (2701 and 2436 kWh/m2 respectively) it is concluded that this site is comparably as good for solar thermal power stations as the Barstow site. The global normal irradiation (usable with sun-tracked photovoltaic panels) had the surprisingly high values of 3551 and 3373 kWh/m2 in 1990 and 1991 respectively. Occasionally peak values of the global normal irradiation greater than the solar constant were measured (up to 1500 W/m2). Missing global normal data from other arid sites do not permit comparison. As known before, the corresponding values in the Swiss Alps are considerably lower (1100-1700 kWh/m2 for the direct normal irradiation and 2000-2500 kWh/m2 for the global normal irradiation respectively, depending on the year and site). In addition to the direct normal and global normal irradiation, the global horizontal and global inclined (30° South) irradiation were measured, amounting to 2353 and 2499 kWh/m2 respectively in 1990. Data have also been collected on wind, rainfall, ambient temperature, dew point and surface pressure. All data are available in a computer accessible form, in particular as a yearly set of 5 min mean values of the direct normal irradiation for 1990. Combining the ground measured data with METEOSAT-data resulted in a unique map of the direct normal irradiation for Jordan and surrounding countries, indicating attractive sites for solar power stations. The measurement campaign was made possible by active support from the Ministry of Energy and Mineral Resources, MEMR and the Jordan Electricity Authority, JEA, both at Amman, as well as by generous financial support of the Swiss Committee for Scientific Research, KWF, Berne.