Renewable energy is defined as energy from a source that is not exhausted when used. Renewable energy sources get their energy from existing, on-going natural processes. These sources are classified as primary sources of energy and are namely biomass, geothermal, hydro, wind, tidal and solar.
The estimated electricity consumption of 30 TW worldwide is projected by 2050, from the current 10 TW. This growth is attributed to the growth of population sizes, infrastructure development and rollout. Conventional energy sources are depleting and the environmental effects of their usage are devastating. The changing climate conditions can be linked directly or indirectly to today’s patterns of energy production. The over reliance on fossil fuels has been under fire from environmentalists and governments around the world are beginning to change policies to encourage the use of renewable energy. One example worth stating here is the introduction of carbon emission tax, which has been delayed here in South Africa until 2015.
The sun is the main source of energy and is abundantly available to all, and can reach all. For this reason, I believe the development of technology to harness this energy will be crucial in supplying power, especially, in places where expensive infrastructure development is required.
This assignment will focus on photovoltaic system. Photovoltaic systems convert solar radiation directly into useful electricity in direct current form. A typical photovoltaic system consists of the following components; PV Solar Array, Diodes, power conditioner, battery storage (optional), inverter and the load and/or utility grid. A usual arrangement of the system is shown in the diagram
Figure 1 BLOCK DIAGRAM OF A PV SYSTEM
PV Solar Array
A PV solar array acts a generator of the system, and is made up of PV modules which are commonly known as solar panels, which are made from linking PV cells. This means solar arrays can be connected to generate as much power as is required.
A photovoltaic cell is a semiconductor device that transforms solar light into useful electrical energy in the direct current (DC) form. A PV cell is made up of two layers of semiconducting material, which, when exposed to light generates electric charges which can be conducted. This phenomenon is known as, “photovoltaic effect”.
To understand the photovoltaic effect, a short theory of semiconductors is discussed; for more detailed information read (Kalogirou, 2014).
There are two types of semiconductors, the n and p types. The n-type and p-type semiconductor are electronically, except the n-type has excessive electrons which are available for conduction while the p-type has positive holes in its structure, see figure.
Figure 2 (a) n- type (b) p-type SEMICONDUCTORS
When the two types are brought together to form a p-n junction, excess electrons move from the n-type to fill holes in the p-type, and the holes from the p-type diffuse to the...