The primary mirror debuts an innovative optical shape called “parabolic cline”, patent pending, with these properties: high concentration and optical yield, uniform flow, suitability for mass production. The optical efficiency exceeds 99% at 300 sun concentration, where the secondary optic steps in to complete the work.
The production process of the primary mirror is under revision, in order to improve the precision of the optic and get repeatable performance. The mirror structure is realized in composite and light alloy, while reflecting layer is in thin silvered glass.
The secondary optic has been designed to collect rays and direct them to the Gallium Arsenide cells, further concentrating the light to the 500 sun final value and homogenizing the flow. The total optical efficiency of the dual stage system is 97%, considering perfectly reflecting surfaces. This is a good value, largely dependent from the regular flow produced by the “parabolic cline” mirror.
To maximize the electric output power, the dense array cell layout has been matched to the incoming light flow. A custom size cell will be developed.
The secondary optic protects the cell dense array from direct rain and dust. Cell protection is completed with a transparent layer. The HCPVT receiver includes light and temperature sensors, used to control the system and to improve tracking precision.
Multiple parallel flows are used to cool the dense array modules: this solution, and the highly conductive materials, limits below 18 °C the heating of cells versus cooling fluid.
The FocalStream product has two versions: the BASE one has a single mirror mounted on a dual axis tracker, the DUAL version has two mirrors. DUAL has better economics due to a lower incidence of fixed cost. The BASE version can be installed both on ground and on roof, while the DUAL version can be installed only on ground and is visually more impacting.
Current simulations show that a 12.8 m2 unshaded area FocalStream mirror, irradiated with 12.800 watt of solar power, can generate up to 10.000 watt of total power with 78% total efficiency.
FocalStream usage scenarios have been described. The cost of generated energy reaches the lowest point when the application makes full use of both heat and power. FocalStream has a broad application potential: sport facilities such as swimming pools, food distribution such as shopping centers or supermarkets, agriculture and food industry such as animal farms, ham curing plants or green houses, Hotels & resorts, residential buildings, offices.
A relevant use of summer heat is to generate cold for ambient cooling with the use of absorption chillers. This solution fits well the RED II Directive, assuring a complete use of heat, thus improving the ROI period. Focalstream plus chiller tests are planned in the second part of the project.
Some dissemination activities have been done with the objective of presenting the project to potential investors and partners. The project was formally presented in “Startup Initiative Cleantech 2016”, 29 Jun 2016 in Milan. Also in “Invest Horizon Investment Summit”, 11 Oct 2016 in Bruxelles and “L’Europa premia l’innovazione: Horizon 2020”, 5 Dec 2016, Bologna. Informal presentations were done in other events. The project web site www.focalstream.eu has been realized to summarize the progress done
