The theory of solar cells explains the process by which light energy in photons is converted into electric current when the photons strike a suitable semiconductor device.
A solar cell is a device that converts light into electricity via the ‘photovoltaic effect’. They are also commonly called ‘photovoltaic cells’ after this phenomenon, and also to differentiate them from solar thermal devices. The photovoltaic effect is a process that occurs in some semiconducting materials, such as silicon.
Solar cells are semiconductor-based devices primarily, which convert sunlight directly to electrical energy through the photovoltaic effect, which is the appearance of a voltage and current when light is incident on a material.
The model will be used to derive the so-called solar cell equation, which is a widely used relation between the electric current density I leaving the solar cell and the voltage V across the converter. For this purpose, we use the relation for generated power P = I ⋅ V and Eq. (127) and we obtain: By using Eqs. (128), (129) we derive:
An ideal solar cell can be represented by a current source connected in parallel with a rectifying diode, as shown in the equivalent circuit of Figure 2. The corresponding I–V characteristic is described by the Shockley solar cell equation Figure 2. The equivalent circuit of an ideal solar cell (full lines).
The characterisation of a solar cell determines how well it performs under solar illumination. The solar spectrum is approximately that of a black body with a temperature of 5780 K. This peaks in the visible range and has a long infra-red tail.
OverviewWorking explanationPhotogeneration of charge carriersThe p–n junctionCharge carrier separationConnection to an external loadEquivalent circuit of a solar cellSee also
The theory of solar cells explains the process by which light energy in photons is converted into electric current when the photons strike a suitable semiconductor device. 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.