Sealed from Dust
Much of the world’s oil is produced in desert locations where blowing sand and dust create unique challenges for solar power. If the mirrors, positioning systems and other vulnerable components are left outdoors, they quickly become covered in a layer of dust that incrementally degrades their performance until they stop working altogether.
To combat this, older exposed mirror systems required frequent cleaning which created an unsustainable O&M expense, especially for large systems in remote locations. In addition, occasional strong winds fired high speed sand particles at the mirrors destroying their smooth surface, permanently reducing their performance. GlassPoint’s enclosed trough technology was designed to avoid these problems.
Interior Stays Clean
The glasshouse protects the mirrors and other vulnerable components from dust and airborne sand. To maintain a pristine interior environment, dehumidified and filtered air is injected into the glasshouse to maintain an internal pressure that is higher than the ambient air. In this way, air escapes by blowing through any small gaps in the structure preventing sand and dust from entering.
Less Soiling = Less Cleaning
As everyone knows, dust, sand and dirt accumulate on surfaces closer to the ground much more quickly than on surfaces that are high up. Research has shown that the soiling rate at four feet above ground level is double the soiling rate at 20 feet. This is bad news for older exposed mirror designs where the key optical surface, the mirror, is placed close to ground level. Not only does this expose the mirrors to a higher soiling rate, but it also puts them in the “abrasion zone” for high speed wind blown sand particles, where they quickly become degraded.
In an enclosed trough system, the vast majority of the light received on a daily basis comes through the glass roof, which is twenty feet above grade and experiences half the soiling rate of surfaces that are four feet above grade. Note that the side walls are not a material source of light because once the sun is high enough in the sky to generate any significant amount of energy, the light path is through the roof, not the side walls. Therefore, dust accumulation and damage from sand blasting of the side walls does not affect the performance of an enclosed trough in the same way as it does in an exposed mirror system.