IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE) e-ISSN: 2278-1676,p-ISSN: 2320-3331, Volume 8, Issue 2 (Nov. - Dec. 2013), PP 01-06 www.iosrjournals.org www.iosrjournals.org 1 | Page Effect of Shading on Photovoltaic Cell 1 Ekpenyong, E.E and 2 Anyasi, F.I 1 Department of Electrical/Electronic Engineering, Cross River University of Technology, P.M.B 1123, Calabar. Nigeria. 2 Department of Electrical and Electronics Engineering, Ambrose Alli University, P.M.B 14, Ekpoma, Edo State, Nigeria. Abstract: Photovoltaic (PV) power systems have been widely applied in commercial and domestic facilities. Electrical Energy Storage (EES) systems are mandatory in standalone PV systems for continuous power supply. In this paper the efficiency and robustness enhancement methods for PV systems under partial shading have been investigated. Partial shading due to moving clouds and shadows of nearby obstacles on the PV module array causes significant efficiency degradation, since shaded and non-shaded PV modules have large discrepancy in their maximum power points. Use of by-pass diodes for each PV module may mitigate the negative effect from partial shading. However, this method alone may still face severe energy efficiency degradation caused by the energy loss due to parasitic effects in the EES elements under variable incoming power from the PV modules. Hence, this paper investigates the effect of shading on photovoltaic cells. I. Introduction Solar energy refers primarily to the use of solar radiation for practical electricity generation. However, there are other renewable energies like natural gas, coal and bio fuel. Solar radiation along with other secondary solar powered resources such as wind, geothermal, tidal and wave power, hydroelectricity and biomass, account for most of the available renewable energy on the earth. Only minuscule fraction of the available solar energy is used [1]. Over the years, solar energy has been gaining ground as a source of electricity. Photovoltaic cells convert sunlight directly to electricity. Photovoltaic (PV) cells utilize semi – conductor technology to convert solar radiation directly into an electric current which can be used or stored. Photovoltaic is a combination of two words “Photo” from Greek root meaning, light and “Voltaic” from volt which is the unit used to measure Electric potentials at a given point [2].The Photovoltaic effect was first noted by a French Physics that certain material would produce small amount of Electric field, ALBERT EINSTEIN described the nature of light and photovoltaic technology that it was too expensive to gain wider spread use in 1954 [3].Sunlight is made up of tiny particles called photons which are being converted to electrical energy. Every hour, enough of this energy reaches the world to meet the world's energy demand for the whole world. Photovoltaic panels consists of many solar cells, these are made of materials like silicon, one of the most common elements on earth. The individual cell is designed with a positive and a negative layer to create an electric field, just like in a battery. As photons are absorbed in the cell, their energy causes electrons to become free, the electrons move toward the bottom of the cell, and exit through the connecting wire. The flow of photons is what we call electricity. By combining solar cells and photovoltaic panels, we can produce just the right amount of electricity to perform a specific job, no matter how large or small, Solar energy is the energy derived from the sun through a form of solar radiation [3]. Solar powered electricity generation relies on photovoltaic cells and heat engines. A partial list of other solar applications include space heating and cooling through solar architecture, day lighting, solar hot water, solar cooking, and high temperature process heat for industrial purposes. Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favourable thermal mass or light dispersing properties, and designing spaces that naturally circulate air. Photovoltaic (PV) cells convert sunlight directly to electricity. They work any time the sun is shining, but more electricity is produced when the sunlight is very strong and strikes the PV cells directly. The basic building block of PV technology is the solar cell. The PV cell consists of two or more layers of semi-conducting material, most commonly silicon. When the silicon is exposed to light, electrical charges are produced and can be conducted away by metal contacts as Direct Current (DC). The current from a single cell is small, so, multiple PV cells are connected together and sealed behind glass to form a module known as SOLAR PANEL [3]. PV allows you to produce electricity, without noise, air pollution and fuel. Most PVs have a life span of 25 – 50 years. Solar power in rural areas is a viable alternative for providing electricity for telecommunications, telemetry, water pumping, lighting, television, DC refrigeration and other low power non- heating applications. Heating appliances such as kettles, toasters, stoves, geysers and heaters are consuming too much energy and