The solar power source is via photovoltaic modules that convert light directly to electricity.

Solar Panels

A solar panel is a large group of solar cells made of silicon. The cells are networked into a panel, each gathering a small amount of energy from sunlight. Multiple panels are required to generate an appreciable amount of electricity which is why solar farm arrays are so large.

Solar Farms

A photovoltaic (PV) power station, also known as a solar farm, is a large-scale PV system designed for the supply of merchant power into the electricity grid. They are differentiated from most building-mounted and other decentralised solar power applications because they supply power at the utility level, rather than to a local user or users.

Unlike the solar panels on domestic or commercial roofs, these panels can be placed away from shade and may be moved so they are at the optimum angle to harvest solar rays throughout the day and throughout the seasons. 

From Farm to Grid

Electricity from solar panels on a solar farm is not currently saved to batteries. Once the energy is gathered on the solar panel it is sent via an inverter to the local electrical grid where it may be bought by an electric utility company.

The electricity used from a solar farm is still from the grid just like always. 

Solar Array Arrangements

The solar arrays on a solar farm are the subsystems which convert incoming light into electrical energy. They comprise of a multitude of solar modules, mounted on support structures and interconnected to deliver a power output to electronic power conditioning subsystems.

The majority of solar farms are 'free field' systems using ground-mounted structures, usually of one of the following types:

Fixed arrays

Many projects use mounting structures where the solar modules are mounted at a fixed inclination calculated to provide the optimum annual output profile. The modules are normally oriented towards the Equator, at a tilt angle slightly less than the latitude of the site. In some cases, depending on local climatic, topographical or electricity pricing regimes, different tilt angles can be used, or the arrays might be offset from the normal East-West axis to favour morning or evening output.

A variant on this design is the use of arrays, whose tilt angle can be adjusted twice or four times annually to optimise seasonal output. They also require more land area to reduce internal shading at the steeper winter tilt angle. Because the increased output is typically only a few percent, it seldom justifies the increased cost and complexity of this design. 

Dual axis trackers

To maximise the intensity of incoming direct radiation, solar panels should be orientated normal to the sun's rays. To achieve this, arrays can be designed using two-axis trackers, capable of tracking the sun in its daily orbit across the sky, and as its elevation changes throughout the year. 

These arrays need to be spaced out to reduce inter-shading as the sun moves and the array orientations change, so need more land area. They also require more complex mechanisms to maintain the array surface at the required angle.

Single axis trackers

A third approach achieves some of the output benefits of tracking, with a lesser penalty in terms of land area, capital and operating cost. This involves tracking the sun in one dimension – in its daily journey across the sky – but not adjusting for the seasons. 

Single axis tracking systems are aligned along axes roughly North-South. Some use linkages between rows so that the same actuator can adjust the angle of several rows at once. 

Power conversion

Solar panels produce direct current (DC) electricity, so solar farms need conversion equipment to convert this to alternating current (AC), which is the form transmitted by the electricity grid. This conversion is done by inverters. To maximise their efficiency, solar power plants also incorporate maximum power point trackers, either within the inverters or as separate units. These devices keep each solar array string close to its peak power point.