![]() ![]() However, not all of the heliostats are used to concentrate their reflected solar energy on the tower at the same time or at the same focal point as extremely higher temperatures may cause the receiver to overheat and melt. However, this is offset by increased tower and installation costs, as well as the expense of extremely precise tracking requirements for a large majority of the heliostat field, and not just the ones furthest away.Ī high temperature heat transfer fluid or working medium in the central receiver absorbs the highly concentrated radiation reflected by the heliostat field and converts this thermal energy into super-heated high pressure steam to be used on the ground to spin a series of turbines, much like a traditional power plant to generate electricity.īy focusing the sunlight and therefore concentrating the solar thermal energy in this way very high temperatures can be achieved from 800 oC to well over 1,000 oC. ![]() Higher towers of between 80 to 110 metres (250-to-350 feet) are preferred as larger denser heliostat fields can be used reducing the effects of shading and also of land usage. The height of the solar tower on which the central receiver is mounted also plays a role in the layout of the heliostat field. The outer heliostats have to be installed further away from their neighbouring heliostats to eliminate shading and require highly precise tracking mechanisms to keep the reflected sunlight at the correct position on the tower. However, heliostats placed far away from the solar tower are less efficient as the strength of the reflected solar energy reduces the longer the distance traveled. Being nearer, they also require less precise solar tracking of the sun. Also the nearest heliostats are less prone to shading from their neighbouring heliostats, but are affected by the tower. Heliostats located nearest to the solar tower are the most efficient as the reflected sunlight has less distance to travel through the air. The layout and positioning of the heliostat field is determined by the position of the solar power tower itself and its geographic location. For multiple mirror heliostats, the position and orientation of the individual mirrors on top of the supporting structure is different for every heliostat within the same heliostat field to take account of its relative position and angle towards the tower. These “heliostats” are basically large mirrors equipped with computer controlled sun tracking mechanisms that keep the mirrors aligned so the reflected rays of the sun are always aimed at the blackened heat absorbing receiver creating a focal point. These reflective dishes capture and concentrate the sunlight onto a central receiver mounted at the top of the high “solar power tower”. The sunlight from many mirror like dish reflectors spread over a large area is focused to one central point achieving an extremely high temperature which is used to produce high pressure steam which is then used to generate electricity.Ī power tower has a circular array of large two-axis tracking reflective dishes or flat multiple mirror heliostats on the ground that accurately follow the sun’s path across the sky during the day. The solar power tower name comes from the fact that the concentrated solar power or CSP, is focused not at the focal point of each heliostat dish but at the top of a very tall vertical tower. Solar towers uses hundreds if not thousands of small sun tracking mirrored solar dish collectors, called heliostats similar to the ones in the previous parabolic and dish collector tutorials that are used to reflect the sunlight directly onto a centrally located heat absorbing receiver. Solar Power Tower The Solar Power Tower for Generating ElectricityĪ Solar Power Tower also known as a Central Receiver, is the big daddy of all concentrating solar collectors. ![]()
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