SOLAR POWER PLANT

SOLAR POWER

                Solar energy is the most effective alternative source of energy i.e. conversion of sunlight into electrical energy. Many developed and developing countries have installed  solar power plant providing significant amount of power into their electrical grids to supply and meet the demand of power,  while in developing countries usage of solar power has reduce dependence on expensive imported fossil fuels.

                There are two methods widely used in solar power plant:-

i. Photovoltaic cell system uses solar panels.

ii. Concentrated solar power or concentrated solar thermal plant.

PHOTOVOLTAIC(PV) CELL SYSTEM

Photovoltaics  or a solar cell, or photovoltaic cell (PV), is a device that converts light energy into electric energy using the photovoltaic effect. Photovoltaic cell were initially used as a source of electricity for small applications like calculator and watches powered by a single solar cell and remote homes powered by an off-grid rooftop solar panel system. Due to the reduction in cost of solar electricity, the number of electrical grid-connected with solar PV systems has grown into very large utility scale, therefore solar power stations with production capacity in terms of megawatts are being built. Solar PV is the fastest growing inexpensive, pollution free method for extracting renewable energy from the Sun.

        Conventional PV systems

Many photovoltaic panels are arranged in an array system. When sunlight incidents on the panels, the PV cells produces direct current (DC) power which fluctuates with the sunlight's intensity. After then the DC current converted in AC(alternating current) voltage to a desired voltage for practical usage, this conversion process usually requires inverter. All of solar(PV) panels are mutually connected through wires, which together forms an array and further connected to an inverter.

After converting DC to AC voltage, the power stored in batteries. In this system there is a need for battery to stored the generated power. So, this system comprises of multiple solar panel, inverter and a battery. Thus the ability to store power provides a significant back-up feature when there is a limited amount of sunlight.

CONCENTRATED SOLAR POWER(CSP) SYSTEM

Concentrating Solar Power (CSP) is a technology where reflectors or mirrors are used to focus the sunlight into the receiver  and this creates significant amount of  heat to create steam which is then used for driving a turbine that will further generate electricity.

In CSP system there are three types of alternative technical methods:

i. Parabolic reflector or trough systems:- In this systems large size of parabolic reflectors which has oil-filled pipes positioned along their centre or focal point called receiver, as shown in the figure. The mirrored reflectors are tilted(facing) towards the sun, and thus focusing the sunlight on the receiver which heats the oil inside it. Now this hot oil is hot enough to boil water, so it generates the steam, so this is then ready for running conventional steam turbines which further runs the electric generators.

ii. Power tower system:- This system uses many large, flat mirrors and a central receiving tower. This mirrors tracks and reflects the sunlight and focuses on the receiver as shown in figure. The receiver is located on the top position of the tower in which the focused or concentrated sunlight heats a fluid, generally as molten salt. This hot fluid is then used for producing steam immediately for working the turbine and electricity generation or it can be also stored for later use.

iii. Dish or engine systems:- In this system mirrored dishes are used, these dishes are more larger than a home satellite dish. In this case a receiver is mounted at the focal point of the dish as shown in figure. For capturing the maximum amount of solar energy, the dish is assembled in such a way that it tracks the sunlight across the sky, and then the sunlight is focused on the receiver. Here the receiver is integrated to a high efficiency combustion engine(external combustion). This engine has thin tubes which contains the fluid(hydrogen or helium gas), due to the sunlight's heat the temperature of the fluid becomes very high, which causes hot gas to expand inside the cylinders that runs the engine's pistons. Now these engine is connected to a crankshaft, which drives an electric generator. The receiver, engine, and generator all of these component comprises a single integrated assembly which is mounted at the focus(receiver) of the mirrored dish.

ADVANTAGES OF SOLAR POWER:-

i. Solar power is free of cost.

ii. Using solar energy does not pollutes the environment.

iii. Solar power can be an alternate option to electrical power grids in remote areas where it is too much difficult and expensive to extend the electricity transmission lines. This makes solar power one of the best option in domestic scale.

iv. Solar energy can power many useful low power consuming electronic devices like calculators, wrist watch etc.

v.  Solar energy is almost infinite. Thus solar energy is an alternate source of energy over the non-renewable fossil fuels.

DISADVANTAGES OF SOLAR POWER:-

i. Solar energy can only be utilized when it is daylight or places where good amount sunlight is available.

ii. There is a cost in manufacturing of its components(reflector, panels and cells)  and other necessary equipments which are required for the conversion of solar energy into electric power.

iii. Installation of solar power plants are very expensive.

iv. Solar power plants output does not match the power output of other conventional power plant like thermal(natural gas or nuclear) power plant.

v. A large area of land is required to place the reflectors or solar panel for extracting the sunlight's energy.

vi. Locations having unreliable climate condition also effects the power production.

vi. The generated electric power needs to be stored in batteries so that the power can be supplied whenever needed. But the batteries are large in numbers and needs extra storage facility. These batteries are also expensive and needs to  be replaced within a specified period.

COMPARISON BETWEEN PHOTOVOLTAIC(PV) CELL SYSTEM AND CONCENTRATED SOLAR POWER(CSP) SYSTEM:-

                In a photovoltaic system solar cells converts sunlight into electricity. It consists of multiple components, including cells, mechanical and electrical components, connections and mountings. But competitive price photovoltaic system makes it more preferable.

                CSP technologies are adopted for large scale purpose since 2011. Future growth of CSP technology will remain healthy despite of its high cost due to its significant production capacity.