How is the efficiency of a solar cell measured Solar Energy Course 2020 Part 7 of 12

Welcome to "How is the efficiency of a solar cell measured?". 📜Get your course certificate📜 ********************************** http://bit.ly/solar-crash-course-ipolytek SUBSCRIBE to see more courses like this one *********************************************** https://www.youtube.com/channel/UCYYX-pqg9CoVhjtC4cW4DIA?sub_confirmation=1 This is the 7th video in our online on Solar Energy. Researchers are continually striving to improve the efficiency of solar cells. But what exactly does the term "efficiency" mean in the solar industry? How is it measured? This video is part of iPolytek's online course on solar energy. iPolytek, Professional Development Courses for Engineers. The efficiency of a solar cell is equal to the ratio between the electrical power it produces and the power it receives from the sun. To measure the efficiency of a solar cell or solar module, the standard value of E = 1000 W / m2 is used. According to this definition, the smaller the area needed to produce Pmax, the higher the efficiency. So, how is Pmax measured? By constructing the IV curve (or the current versus voltage curve) of the solar cell. The current that is measured when there is no voltage is called the short-circuit current, Isc. At this point, power equals 0. The voltage that is observed when no current is flowing is called the open-circuit voltage, Voc. At this point, power also equals 0. Since, Power = I x V : The P-V curve is obtained by multiplying, point by point, all the voltages and currents between the short circuit and open circuit conditions. Then we can simply read Pmax since it is the peak of the P-V curve. Once we know Pmax, we can read Vmp (the voltage at maximum power) from the P-V curve. Next, we use the I-V curve to determine Imp (current at max power) from Vmp. In general, Pmax is found near the elbow of the I-V curve. We see that Pmax decreases considerably as the irradiance decreases (because of cloud cover for example). Temperature also has a strong influence on Pmax. As the temperature of the solar cell increases the voltage it generates decreases. At the same time, the current it produces increases very slightly. There the net effect is an overall decrease in the power produced by the solar cell. Standardized tests are used to determine Pmax. They make it possible to compare devices that differ in technology and manufacturer. These tests are carried out under the following standardized conditions: - Incident radiation flux 1000 W/m2 - A solar cell temperature of 25 degrees Celsius - 4 measuring points are used (2 for voltage and 2 for current) - Spectral conditions Air Mass 1.5 This means that the composition of the spectrum used is identical to the solar spectrum after it crosses an air thickness equal to 1.5 atmospheres. This corresponds to an angle of incidence of 41.8 measured from the horizontal. Lamps meeting these specs are placed above the solar cell. The solar cell is placed block allows the measurement its front and voltage and current Cooling water (runs through block) to maintain the cell temperature at 25 degrees Celsius. Finally, a variable load is used to taking readings along I-V curve. In this video, we've seen how efficiency is defined and measured. We're ready to calculate the number of modules we need for a given power output. What are the basic calculations involved in sizing a PV system? Find out in our next video! See you soon and thanks for watching. References: ************ 1. Alternative Energy Tutorials. Solar Cell I-V Characteristic and the Solar Cell I-V Curve. http://www.alternative-energy-tutoria.... (Accessed 19 July 2018) 2. Architecture et Climat - Faculté d'architecture, d'ingénierie architecturale, d'urbanisme (LOCI b) – Université catholique de Louvain (Belgique)., https://www.energieplus-lesite.be/ind... (accessed 19 July 2018). 3. Salama, M. Inspired by PVEducation. https://www.pveducation.org/pvcdrom/c... (Accessed July 4, 2018). #SolarPV #Photovoltaic #SolarCell #HowEfficientAreSolarCells