BODIPY Dyes in Solar Energy

Introduction

World's energy demand is growing fast because of increasing population and technological advancements. It is therefore important to go for reliable, cost effective and everlasting renewable energy source for energy demand arising in future. Solar energy, among other renewable sources of energy, is a promising and freely available energy source for managing long-term issues in energy crisis. Solar energy is the conversion of sunlight into usable energy forms. It is an essential source of renewable energy that has sufficient capacity for the global energy need, and it is the most important that can address the issues of energy problems (Lewis & Nocera, 2006). Solar energy is free, clean and abundant in most places throughout the year and is important especially at the time of high fossil fuel costs and degradation of the atmosphere by the use of these fossil fuels. It can be converted by natural and technological processes into other useful forms of energy. Such as the chemical process through photosynthesis or the electric process using photovoltaic (PV) equipment to produce electricity or the thermal process to produce heat or the conversion of solar radiation into mechanical energy. Relatively well-spread over the globe since solar energy comes from the sun and it represents a limitless source of power (Ladomenou et al., 2017). Solar photovoltaics (PV), solar thermal electricity and solar heating and cooling are well established solar technologies. These technologies are depending on how they capture and distribute solar energy or convert it into solar power. The conversion of solar energy into electricity is done through photovoltaic (PV) solar cells. Solar cells represent the building block and main component of PV systems. A solar cell is defined as an electrical device that directly converts the energy of photons into direct current (DC) electricity through a chemical/physical phenomenon called the photovoltaic effect (Shubbak, 2019). Solar PV combines two advantages: module manufacturing can be done in large plants, which allows for economies of scale, and it is also a very modular technology and can be deployed in very small quantities at a time. This allows for a wide range of applications. Systems can be very small, from personal electronics or off-grid applications, up to utility-scale power generation facilities. However, solar radiation that is absorbed but not converted into electricity promotes the temperature increase of the solar cells, thus reducing their conversion efficiency. To counteract this phenomenon, the cells may be cooled by a working fluid (thermal fluid) in order to maintain a high level of conversion efficiency. In this setup, the thermal fluid - water or air - extracts the heat from the cells to be used elsewhere, resulting in a hybrid solar equipment with simultaneous generation of electric energy and thermal energy: this is called a Photovoltaic-Thermal collector or simply PVT. Thus, a PVT hybrid solar collector is a device formed by a PV module with an attached thermal unit on its back, being thus considered a cogeneration equipment. The importance of this equipment is that it can generate energy, electric and thermal simultaneously, with a good level of efficiency and in a smaller area than current thermal collectors and photovoltaic panels operating separately (Ramos et al., 2019). In the 21^st century solar energy is expected to become increasingly attractive as a renewable energy source because of its inexhaustible supply and its nonpolluting character, in stark contrast to the finite fossil fuels coal, petroleum, and natural gas. Solar energy could be a best option for the future world because of several reasons: First, solar energy is the most abundant energy source of renewable energy (Panwar et al., 2011). Solar energy reaches the earth in various forms like heat and light. Studies revealed that global energy demand could be fulfilled by using solar energy satisfactorily as it is abundant in nature and freely available source of energy with no cost (Lewis, 2007). Second, it is a promising source of energy in the world because it is not exhaustible, giving solid and increasing output efficiencies than other sources of energy (Nozik, 1978).