Actively Focused Heliostat with Mechanically Coupled Shape Change

This invention is a heliostat that has its toroidal reflector continuously altered through the day. A simple mechanical coupling is used to change the reflector shape over the course of the day. Dual-axis mounts were found to maximize capability. In this way, the heliostat realizes the highest possible concentration of sunlight. 

This model also reduces costs by reducing mechanical complexities. Since the heliostat field in a concentrated solar power project can account for up to 50% of the capital cost, these reductions are critical to budget management. 

Background: 
Researchers at the University of Arizona demonstrated a prototype that forms solar disc images throughout the day at the cost of additional motor-driven actuators and a system for control and power. However, the actively focused heliostat is simpler and less expensive; it requires no added motors or control systems.

To obtain a high concentration in a field of many heliostats which all direct sunlight toward a receiver, it must be possible to pack them closely together without the light reflected from one heliostat being blocked by the other. It was shown that the profiles of the reflectors in this innovation, which are rectangles with struts at each of the four corners, allow for this dense packing method. The result is improved energy conversion and a wider range of applications.

Applications: 

• Light concentration
• Solar energy harvesting
• Clean water production
• High-temperature industrial projects
• Electrical, steam, and chemical energy production
• Residential, commercial, and industrial lighting and heating

Advantages: 

• Cost reduction
• Variable reflector shape
• Mechanical complexity reduction
• Dual-axis mount for maximized capability