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Photovoltaic (PV) systems use semiconductor cells that convert sunlight directly into electricity. Direct current from the PV cells, which are arrayed in flat panels, flows to inverters that change it to alternating current.
A solar cell, also known as a photovoltaic cell (PV cell), is an electronic device that converts the energy of light directly into electricity by means of the photovoltaic effect. [1] It is a form of photoelectric cell, a device whose electrical characteristics (such as current, voltage, or resistance) vary when it is exposed to light.
The theoretical studies are of practical use because they predict the fundamental limits of a solar cell, and give guidance on the phenomena that contribute to losses and solar cell efficiency. Band diagram of a solar cell, corresponding to very low current (horizontal Fermi level), very low voltage (metal valence bands at same height), and ...
The peak of the emission spectrum occurs at 1.29 eV for Yb 2 O 3 and 0.827 eV for Er 2 O 3. As a result, Yb 2 O 3 can be used a selective emitter for silicon cells and Er 2 O 3, for GaSb or InGaAs. However, the slight mismatch between the emission peaks and band gap of the absorber costs significant efficiency.
The most common device structure for CIGS solar cells is shown in the diagram (see Figure 1: Structure of a CIGS device).Soda-lime glass of about of 1–3 millimetres thickness is commonly used as a substrate, because the glass sheets contains sodium, which has been shown to yield a substantial open-circuit voltage increase, [15] notably through surface and grain boundary defects passivation. [16]
The first demonstration of the photovoltaic effect, by Edmond Becquerel in 1839, used an electrochemical cell. He explained his discovery in Comptes rendus de l'Académie des sciences, "the production of an electric current when two plates of platinum or gold immersed in an acid, neutral, or alkaline solution are exposed in an uneven way to solar radiation."
The primary function of a solar cell is the conversion of light energy into electrical energy by means of the photovoltaic effect. [16] In particular, polymer-fullerene bulk heterojunction solar cells are promising because of their potential in low processing costs and mechanical flexibility in comparison to conventional inorganic solar cells.