How it works
The Power-Spar is a two-axis tracking solar concentrator - one motor adjusts the tilt of the mirrors according to the elevation angle of the sun; the second motor rotates the entire array according to the azimuth angle.
The individual mirrors are parabollic so they focus the sun onto the absorbers which are suspended above the mirror surfaces - the light is concentrated to more than 1000 suns inside the absorber.
The Power-Spar is avaiable in two sizes - the PS-35 and the PS-140 (the PS-35 has approximately 35 m2 of reflective surfaces; the PS-140 has 140 m2 ). Each size is currently available in three different configurations - Combined PV & Thermal ( CPVT ); PV-only and Thermal-only. Another variant which simply transports the concentrated light is also under development and will be available commercially in the near future.
Conventional flat plate PV cells suffer a reduction of 0.09% (absolute efficiency) for every degree about 25°C whereas the Power-Spar's III-V (triple junction) cells have losses of only 0.06%.
So, when the cell temperatures rise to 45°C, the flat plate system efficiency will decrease by 1.8% while the III-V cells reduce by only 1.2%.
However, from a production perspective this is a 10% loss for a conventional PV system (i.e., 1.8% of an 18% cell) but a very much smaller fraction for the Power-Spar because the initial III-V cell efficiency is more than 35%.
A heat transfer fluid ( HTF ) is run over the backsides of the PV cells to keep them cool (and the maintain their high efficiency). In the CPVT system, the heated fluid is then used for space, process or domestic water heating. With the inclusion of a Solar Thermal Air-Conditioning ( STAC ) unit, the thermal energy can also be used to provide cooling. In a PV-only system, the thermal energy in the HTF is dissipated through highly efficient coils. In both the CPVT and PV-only configuations, the temperature of the HTF is kept as low a possible to maximize the electrical output of the system.
The fluid temperatures in the Thermal-only configuration can be tailored to suit the requirements of the installation - ranging up to several hundred °C. An appropriate heat transfer fluid will be selected to match the desired outlet temperatures.
Visit the product info page for specification sheets or contact our sales staff for additional information.
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