Solar PV Theory.pdf

In figure 14 a voltage source is arranged so that the

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In Figure 14, a voltage source is arranged so that the negative terminal supplies electrons to the N-type material. These electrons diffuse toward the junction. The positive terminal removes electrons from the P-type semiconductor, creating holes that diffuse toward the junction. If the source voltage is great enough to overcome the junction potential (0.6 V in Si), the N-type electrons and P-holes combine annihilating each other. This frees up space within the lattice for more carriers to flow toward the junction. Thus, currents of N-type and P-type majority carriers flow toward the junction. The recombination at the junction allows a N-type P-type Depletion region Electrons Holes Baron or gallium atom Missing electron (hole)
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The Diode Discussion 8 Solar Power current to flow through the P-N junction (i.e., a continuous flow of electrons through the junction). Such a junction is said to be forward biased. Figure 14. Forward bias repels carriers toward junction. If the voltage source polarity is reversed as shown in Figure 15, majority carriers are attracted away from the junction toward the voltage source terminals. The positive terminal attracts N-type electrons majority carriers away from the junction. The negative terminal attracts P-type majority carriers, holes away from the junction. This increases the thickness of the non-conducting depletion region. There is no recombination of majority carriers; thus, no conduction. Such a junction is said to be reverse biased. Figure 15. Reverse bias attracts carriers toward battery terminals, away from junction. A P-N junction made of silicon is in fact a silicon diode. The cathode of a diode symbol corresponds to the N-type semiconductor. The anode corresponds to the P-type semiconductor. See Figure 16. Figure 16. Schematic symbol and P-N junction representation of a diode. N-type P-type Electrons flow in conductors N-type P-type Depletion region Negligible current N-type P-type Electrons Holes Cathode Anode
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The Diode Procedure Outline Solar Power 9 When a diode is forward biased, the current increases slightly as the voltage is increased from 0 V. In the case of a silicon diode a measurable current flows when the voltage approaches 0.6 V. As the voltage is increased past 0.6 V, current increases considerably. Increasing the voltage well beyond 0.7 V can result in current high enough to destroy the diode. The forward voltage E F , is a characteristic of the semiconductor: 0.6 V to 0.7 V for silicon, 0.2 V to 0.3 V for germanium. The forward current ranges from a few milliamperes (mA) for small signal diodes to thousands of amperes for power diodes.
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Solar Power 10 The Discussion covers the following points: Photovoltaic cell, module, and panel Characteristic E-I curve of a PV cell Electric power output Irradiance Standard test conditions (STC) Efficiency Lab-Volt Solar Panel Test Bench Lab-Volt Monocrystalline Silicon Solar Panel Photovoltaic cell, module, and panel A photovoltaic (PV) panel is a device that produces electrical energy when it is illuminated by a source of light. By placing PV panels outdoors, it is possible to
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