Solar PV Theory.pdf

# Standard test conditions stc since the e i curve of a

• 28

This preview shows pages 15–17. Sign up to view the full content.

Standard test conditions (STC) Since the E-I curve of a PV module, and thus the output power, depends on cell illumination, standard test conditions (STC) have been devised to determine the specifications of PV panels (e.g. values of I SC and E OC ) and to enable fair comparisons of one PV module with another. The standard test conditions specify a cell temperature of 25°C (77°F) (not the ambient temperature) and an irradiance of 1000 W/m 2 (92.9 W/ft 2 ) with an air mass coefficient equal to 1.5 (AM1.5). The air mass (AM) coefficient characterizes the solar spectrum after the solar radiation has traveled through the atmosphere. The standard test conditions approximately represent solar noon near the spring and fall equinoxes in the continental United States with PV module surface aimed directly at the Sun. Efficiency When light illuminates a PV module or panel, only a portion of the energy contained in the incident light is converted into electric power. The more efficient the PV cells in the PV module or panel are, the higher the amount of electric power produced. The efficiency of PV modules or panels is usually calculated using the characteristic E-I curve obtained under STC and Equation (1). Solar noon is the moment during a day when the Sun is at the highest point in the sky. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0 2 4 6 Cell current (A) 250 W/m 2 500 W/m 2 750 W/m 2 1000 W/m 2 1000 W/m 2 = 92.9 W/ft 2

This preview has intentionally blurred sections. Sign up to view the full version.

The Solar Panel (Photovoltaic Panel) Discussion Solar Power 1 6 100 × × = A Irradiance MPP η (1) where η is the efficiency of the PV module or panel in % MPP is the maximum power point of the PV module or panel in W at STC Irradiance is the irradiance in W/m 2 (W/ft 2 ) at STC A is the surface area of the PV module or panel in m 2 (ft 2 ) As an example, under the standard test conditions [25°C (77°F), 1000 W/m 2 (92.9 W/ft 2 ), AM1.5], a solar panel having a 20% efficiency and 0.02 m 2 (0.22 ft 2 ) of surface area will produce approximately 4.0 watts of power. The efficiency of PV cells made of single-crystal silicon (monocrystalline silicon) varies significantly depending on the quality of the silicon that is used to produce the cells. Typical efficiency of monocrystalline silicon cells used in commercial PV panels is about 12% when measured at STC. Lab-Volt Solar Panel Test Bench The Solar Panel Test Bench is a module designed to be inserted in a Lab-Volt workstation, into which a solar panel can be installed. A powerful halogen lamp is used to illuminate the solar panel under test. The distance between the halogen lamp and solar panel can be changed to adjust the irradiance. A ventilation system is provided in the Solar Panel Test Bench to keep the solar panel at near room temperature. The halogen lamp and ventilation system can be turned on and off through switches mounted on the front panel of the test bench. A potentiometer and a set of diodes are included in the Solar Panel Test Bench.
This is the end of the preview. Sign up to access the rest of the document.
• One '14
• Photovoltaics, Solar cell, PV cell, Photovoltaic module, pv module

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern