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PowerPoint ® Presentation Photovoltaic Systems Cells, Modules, and Arrays Photovoltaic Cells Current–Voltage (I–V) Curves PV Device Response Modules and.

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Presentation on theme: "PowerPoint ® Presentation Photovoltaic Systems Cells, Modules, and Arrays Photovoltaic Cells Current–Voltage (I–V) Curves PV Device Response Modules and."— Presentation transcript:

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2 PowerPoint ® Presentation Photovoltaic Systems Cells, Modules, and Arrays Photovoltaic Cells Current–Voltage (I–V) Curves PV Device Response Modules and Arrays Arizona Solar Power Society Photovoltaic Cells Current–Voltage (I–V) Curves PV Device Response Modules and Arrays Arizona Solar Power Society

3 Chapter 5 Cells, Modules, and Arrays The basic building blocks for PV systems include cells, modules, and arrays.

4 Chapter 5 Cells, Modules, and Arrays Semiconductor materials with special electrical properties can be made by adding small amounts of other elements to silicon crystals.

5 Chapter 5 Cells, Modules, and Arrays The photovoltaic effect produces free electrons that must travel through conductors in order to recombine with electron voids, or holes.

6 Chapter 5 Cells, Modules, and Arrays Various PV materials and technologies produce different efficiencies.

7 Chapter 5 Cells, Modules, and Arrays Monocrystalline silicon wafers are sawn from grown cylindrical ingots.

8 Chapter 5 Cells, Modules, and Arrays Polycrystalline silicon wafers are sawn from cast rectangular ingots.

9 Chapter 5 Cells, Modules, and Arrays Several steps are involved in turning silicon wafers into PV cells.

10 Chapter 5 Cells, Modules, and Arrays Diffusion of phosphorous gas creates a thin n-type semiconductor layer over the entire surface of a p- type wafer.

11 Chapter 5 Cells, Modules, and Arrays The different materials, processes, and manufacturing steps produce a range of PV cell types.

12 Chapter 5 Cells, Modules, and Arrays An I-V curve illustrates the electrical output profile of a PV cell, module, or array at a specific operating condition.

13 Chapter 5 Cells, Modules, and Arrays Open-circuit voltage is easily measured with test instruments.

14 Chapter 5 Cells, Modules, and Arrays Using in-line and clamp- on ammeters are two methods of measuring short-circuit current.

15 Chapter 5 Cells, Modules, and Arrays A power versus voltage curve clearly shows the maximum power point.

16 Chapter 5 Cells, Modules, and Arrays Fill factor represents the shape of an I-V curve.

17 Chapter 5 Cells, Modules, and Arrays Efficiency is a measure of how effectively a PV device converts solar power to electrical power.

18 Chapter 5 Cells, Modules, and Arrays A PV device can be modeled by a current source in parallel with a diode, with resistance in series and parallel.

19 Chapter 5 Cells, Modules, and Arrays Increasing series resistance in a PV system flattens the knee in the I-V curve, reducing maximum power, fill factor, and efficiency.

20 Chapter 5 Cells, Modules, and Arrays Decreasing shunt resistance reduces fill factor and efficiency and lowers maximum voltage, current, and power, but it does not affect short-circuit current.

21 Chapter 5 Cells, Modules, and Arrays Voltage increases rapidly up to about 200 W/m 2, and then is almost constant. Current and maximum power increase proportionally with irradiance.

22 Chapter 5 Cells, Modules, and Arrays Increasing cell temperature decreases voltage, slightly increases current, and results in a net decrease in power.

23 Chapter 5 Cells, Modules, and Arrays Modules are constructed from PV cells that are encapsulated by several layers of protective materials.

24 Chapter 5 Cells, Modules, and Arrays An array is a group of PV modules integrated as a single power-generating unit.

25 Chapter 5 Cells, Modules, and Arrays Several modules may be connected together to form a panel, which is installed as a preassembled unit.

26 Chapter 5 Cells, Modules, and Arrays A junction box on the back of a module provides a protected location for electrical connections and bypass diodes.

27 Chapter 5 Cells, Modules, and Arrays PV cells or modules are connected in series strings to build voltage.

28 Chapter 5 Cells, Modules, and Arrays The overall I-V characteristics of a series string are dependent on the similarity of the current outputs of the individual PV devices.

29 Chapter 5 Cells, Modules, and Arrays Strings of PV cells or modules are connected in parallel to build current.

30 Chapter 5 Cells, Modules, and Arrays The overall I-V curve of PV devices in parallel depends on the similarity of the current outputs of the individual devices.

31 Chapter 5 Cells, Modules, and Arrays Modules are available in several sizes and shapes, including squares, rectangles, triangles, flexible units, and shingles.

32 Chapter 5 Cells, Modules, and Arrays Bypass diodes allow current to flow around devices that develop an open-circuit or high-resistance condition.

33 Chapter 5 Cells, Modules, and Arrays A bypass diode limits reverse current through PV devices, preventing excessive power loss and overheating.

34 Chapter 5 Cells, Modules, and Arrays Module labels must include performance ratings for the module and may include other information used to design a PV system.

35 Chapter 5 Cells, Modules, and Arrays Various test conditions can be used to evaluate module performance and may produce different results.

36 Chapter 5 Cells, Modules, and Arrays Modules are added in series to form strings or panels, which are then combined in parallel to form arrays.


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