The Performance of Photovoltaic (PV) Systems: Modelling, Measurement and Assessment

• 温情杀手

  2020-05-15
  When calculating performance index, in contrast, we compare the measured energy output of a power plant to the energy output calculated with a potentially quite complex model. As such models try to accurately consider various loss factors, performance index actually reaches 100% once the plant delivers the amount of energy that is expected from the simulations. In IEC 61724-1, performance index is defined as the ratio of the measured AC energy to the expected AC energy.
• 温情杀手

  2020-05-15
  Performance ratio and performance index are standardized indicators defined consistently for nonconcentrator and concentrator PVs. Performance ratio, as defined for nonconcentrator systems in IEC 61724-1 and for concentrator systems in IEC 62670-2, is a measure expressed in percent, for the overall effect of losses on the power output of a plant.
• 温情杀手

  2020-05-15
  CPV plants are usually equipped with SCADA (‘Supervisory Control And Data Acquisition’) systems which include data loggers and sensors for the measurement of electrical and meteorological parameters.
• 温情杀手

  2020-05-14
  The rating procedure consists of three measurement methods: outdoor I–V measurements, outdoor thermal transient measurement (TTM) and indoor I–V measurements.
• 温情杀手

  2020-05-14
  (I) IEC 62670-1 defines the ambient conditions for the rating: concentrator standard test conditions (CSTC) and concentrator standard operating conditions (CSOC).(II) IEC 62670-2 defines how to measure the energy of a CPV system.(III) IEC 62670-3 defines the methods and procedure to determine the power output of CPV modules at CSTC and CSOC.(IV) IEC 62670-4 defines how to rate the energy produced by a CPV system.
• 温情杀手

  2020-05-14
  The cell temperature influences mainly the VOC of the module whereas the lens temperature influences mainly the ISC of the module.
• 温情杀手

  2020-05-14
  Typically, for the lattice-matched triplejunctioncell, three SMR values are calculated: SMR(top,mid)=SMR(1,2), SMR(top,bot)=SMR(1,3) and SMR(mid,bot)=SMR(2,3).If all three SMR values are close enough to unity, the prevailing spectral condition is considered as equivalent to the standard spectral condition. The current IEC draft standard 62670 considers SMR within 1.0±3.0% as close enough.
• 温情杀手

  2020-05-14
  The integral value of the spectral irradiance distribution is measured in a similar manner as that for flat-plate PV by using a pyrheliometer. A pyrheliometer has the same operating principle as a pyranometer, but measures the irradiance only in an opening angle of ±2.5 degrees.
• 温情杀手

  2020-05-14
  The impact of the spectral distribution on module performance results from the use of multijunction solar cells. Multijunction solar cells consist of several subcells with different bandgap energies which are internally series connected. Each subcell absorbs light in a different wavelength range.
• 温情杀手

  2020-05-14
  The optical efficiency accounts for losses in the optical element. These losses could be due to reflection, but also due to refraction, chromatic aberration or other optical losses. Typical practical optical efficiencies are in the range from 78% to 90%. It must be noted that the optical efficiency depends also on the concentration level. Higher concentration factors reduce the optical efficiency for a given optical element.
• 温情杀手

  2020-05-12
  The IEC standards related to PV hybrid systems are mainly linked to the JWG 1 (JWG TC 82/TC 88/TC 21/SC 21A) of the Technical Committee (TC) 82 of IEC (International Electrotechnical Committee).
• 温情杀手

  2020-05-09
  The BDI has dual control and operates in two modes: VCVSI (voltage control voltage source inverter) mode, as a rectifier, and CCVSI (current control voltage source inverter) mode, operating as an off-grid inverter. In addition, it has intelligent battery management for charging and discharging the batteries.
• 温情杀手

  2020-05-09
  Nowadays, charge controllers provide several communication options. They can use a proprietary protocol and/or nonproprietary open standard such as Modbus and Modbus TCP/IP protocols for RS-232, EIA-485 and ethernet networks. Additionally, HTTP, SMTP and SNMP are often supported for web page, e-mail and network message support.
• 温情杀手

  2020-05-09
  There are four general types of charge controllers, categorized by the method used to regulate the charge from the solar modules to the batteries: shunt type charge controllers; series type charge controllers; pulse-width modulation charge controllers and MPPT charge controllers.
• 温情杀手

  2020-05-09
  A battery charge controller (BCC) regulates the flow of electricity from the PV generator to the battery. Its function is to regulate the voltage and current from the PV array in order to prevent overcharging and also overdischarging of the battery.
• 温情杀手

  2020-05-09
  Pico PV systems are very small-scale PV systems usually large enough for the basic electricity needs of one household, ranging from 1 to 10 W of PV capacity. These systems focus on lighting, but can often be designed to also run other small electrical appliances such as mobile phone charging, radios and MP3 players.
• 温情杀手

  2020-05-09
  An integrated PV-ASHP system is a system where the heat pump is powered by PVs. The system can be made up of five parts as follows: PV generator, a PV controller, batteries, a DC–AC inverter and an ASHP system.
• 温情杀手

  2020-05-09
  Solar pumps are classified into three types according to their application: submersible, surface and floating water pumps. The water pumps may be driven by DC or AC motors. The earlier PV pumping systems were principally based on DC motors. DC motors present the drawback of maintenance expenses due to frequent brush replacements. Brushless permanent magnet DC motors have been introduced in some systems. Recent developments in induction motor technology made this option attractive among the AC motor-based pumping set-ups. The induction motor is more robust, requires much less maintenance and is available at lower cost than a DC motor.
• 温情杀手

  2020-05-09
  Stand-alone (off-grid) systems were the origin of photovoltaic (PV) systems. The world’s first PV companies were launched in the early 1970s to develop products for remote power applications like navigation aids and telecommunications, and in developing countries. The first oil shock in 1973 led to an increase in interest in PV for electricity generation, new R&D and new companies. In 1978 the first PV water pumps in Africa, working with Mali Aqua Viva, were installed. In 1978 the World Bank/UNDP also launched the Global Solar Pumping Programme.
• 温情杀手

  2020-04-15
  Most ground measurements of global solar irradiation for long-term data sets are made using a pyranometer, which is a thermopile device whereby a change in temperature caused by the absorption of sunlight provides a voltage signal proportional to the incident irradiation. Advantages of the pyranometer are that its response is spectrally insensitive and that it measures across a wide spectral range from 280 to 2800 nm [2]. This makes the irradiation measurements suitable for a wide range of applications.