Conversion from sunlight to electricity


   Solar cells are mainly made of silicons and other conductive materials. When a sunlight hits the solar cells, the electrons are released via chemical reaction. This allows for electricity to be produced. For best results panels cannot be in the shade. Weather conditions are not usually a concern since temperatures do not affect PV systems and snow can melt quickly upon contact with panels due to direct sunlight position. [1]


    The top layer of a PV cell has metal conductor strips underneath which lies an antireflective coating (ARC) to maximise sunlight absorption. Beneath this layer lie two more layers of treated (‘doped’) silicon which is a semi-conductor. The upper layer out of the two contains an excess of electrons (called n-type), while the lower layer contains an excess of ‘holes’ (called p-type). Between these two layers is a region termed as the ‘p-n junction’. In this area paired electrons and ‘holes’ come together to form an electric field. This electric field in effect, behaves like a diodeit allows electrons to flow from the P side to the N side, but not the other way around. [2], [3]


    Sun rays consist of photons (light particles). When the photons are incident on the solar PV panels, the energy they release is used to ‘break up’ the particles present in the p-n junction. For this to happen, the energy released by the photons must be greater than the ‘band gap’ of the p-n junction, which is the energy binding the particles together. The electrons which get freed move into the n-type layer, while the holes go down into the p-type layer. The resultant movement of the electrons and hole leads to the formation of a direct current which travels through an inverter and gets converted to alternating current which is used in the household. Hence it is essentially the direct conversion of light energy into electricity at the atomic level. The figure below shows the different components and the process involved: [3]

Conversion of energy in solar PV cells [3]


    To construct solar PV modules from the individual cells, a number of cells are connected electrically to each other and mounted on a supporting frame (often on the rooftop). The modules are designed to produce electricity at specified voltages. Multiple modules are then wired together to form an array as shown below. Usually the quantity of electricity generated is directly proportional to the area of the module or array. They can be connected in both series and parallel electrical arrangements to produce any required voltage and current combination.

Going from solar cells to solar PV arrays [4]

Primary author: Amos Han
Editor: Apratim Mukherjee

Leave a Reply

Your email address will not be published. Required fields are marked *