Functions of a Solar Farm
Solar farms or photovoltaic power plants generate solar energy for the sole purpose of providing commercial electricity to the main grid. Solar power is increasingly becoming one of the most popular forms of electricity generation today. It has overtaken traditional power sources such as coal in terms of popularity and pace of adoption.
A typical solar farm consists of huge arrays of solar panels lined up across huge open fields which are sometimes combined with agricultural lands, hence the term ‘farms’. Due to the sheer scale and size of utility solar power generation, such solar farms are located away from main cities and populated areas. Solar farms use PV panels that convert the energy of the photons in sunlight into electricity. When a photon strikes the semiconductor panel, its energy is absorbed and an electron is released which forms an electric current.
Arrays and inverters used in solar farms
Regular solar arrays are ground-mounted PV panels which are tilted.
They can be fixed at a particular angle or be coupled with a solar tracker to maximize sun exposure. Additionally, solar inverters are required to convert the power from DC to AC in order to make a connection to the utility grid. A secure connection is established through a 3-phase, high voltage step-up transformer of range 10 kV and above.
Solar arrays have two keys components. The first is the solar module which consists of the PV panels. They are responsible for converting sunlight into energy. The second is the support structure which is responsible for optimizing the orientation of the panels to capitalize on sun exposure. Arrays are then connected to electronic subsystems which then process it before connecting it to the grid. There are two main kinds of solar arrays which solar farms use: fixed and single or dual axis trackers. As the name suggests fixed arrays do not change their position or angle with the movements of the sun.
While they may not be efficient at utilizing the complete production of the sun, they are cheap and easy to install. Arrays with dual-axis trackers change their angle with the movement of the sun and adjust to changes in the sun's elevation throughout the year. Such dual axis arrays are extremely expensive and have high operational and maintenance costs due to high precision and moving parts. A convenient compromise between cost and technology are the single axis trackers which only tracks the daily movements of the sun.
For converting the electricity from DC to AC, solar farms either use centralized or string inverters. String inverters are usually used in small farms where capacities lie in the range of 10kW. String inverters are typically used in small solar parks which increase their energy efficiency by focusing on specific areas.
Subsequently, transformers are used as utility grids operate at a much higher voltage than what inverters deliver. Inverters produce a voltage of about 500V where grid operates in tens of thousands. By combining arrays with inverters and transformers a self-sufficient system can be formed which can work as a solar farm.