- The first tests of a complete module in June of 2011 generated 2 kW of electricity. Above, the receiver’s ball lens glows white with concentrated sunlight.
Power Generation
In the summer of 2011, a team of REhnu and University of Arizona engineers completed a full scale module prototype. The module generates 2 kW of electricity, and has operated for over 100 hours without incident. The full scale module uses a 3.15 m square (10’4”-by-10’4” ) dish reflector and a receiver with thirty-six 15 mm square cells, operated at a geometric concentration of 1200x. The active cooling system with four radiators in a square above the receiver works well, with the cell temperature running about 25°C above ambient.
Tolerance to wind buffeting
The prototype module is mounted in the spaceframe structure designed to hold eight identical modules and track the sun. During a month of daytime solar tracking, the prototype tracker (spaceframe structure), at that time loaded with eight tarps in place of dish reflectors, was measured to point within 0.1° of the sun for over 99% of the time. Thus even in a less sheltered location on a solar farm, we can expect very small loss to wind buffeting.
In an earlier prototype (shown below) with an eight-cell receiver was used to measure the power response to off-axis pointing, as generated by wind buffeting. The drive was switched off, and the output measured as the sun moved across the sky, passing through the system axis. The result is shown in the figure, below right. We find an angle of acceptance for power >90% of its on-axis peak of ±0.6°. Such a wide tolerance is enough to maintain full power in all but the strongest wind gusts, because the spaceframe structure and its support have shown to be very stiff, despite their lightweight construction.
