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Breakthrough high performance cost competitive solar concentration system for combined heat and power generation

Periodic Reporting for period 4 - FOCALSTREAM (Breakthrough high performance cost competitive solar concentration system for combined heat and power generation)

Reporting period: 2018-02-01 to 2019-04-30

The European Directive on Cogeneration was transposed into national law in 2006 and obliges all European Governments to promote small-scale co-generation.
The New Renewable Energy Directive (RED II), active in the 2020-2030 period, commits on decarbonizing the heating and cooling sector:
• removing barriers hampering the development of renewable heating and cooling
• decentralizing energy and promoting self-consumption
• promoting thermal storage in buildings and district systems
RED II has a strong focus on empowering energy consumers and local authorities, promoting mechanism to locally store renewable energy.
At present there are several devices that transform solar energy into thermal and electrical energy, but most of them share a low performance, high surface requirements and high maintenance costs. FocalStream is a new co-generator based in High Concentration Photo Voltaic & Thermal (HCPVT) technology with unique performances.
The FocalStream HCPVT co-generator produces at least 3 kW electrical and 6 kW thermal with a gross area of 13.5 m2, saving a 55% of space and decreasing 40% the weight compared with solar thermal and PV panels separately. In addition, FocalStream reaches a total yield greater than 75%. A Focalstream plant costs less than two separated solar PV and solar thermal plants with same productivity.
The Focalstream approach fits well in the RED II directive of promoting a local production and consumption of renewable energy, using storage mechanism to increase the self-consumption of heat and power. It is also the ideal solution to decarbonize the heating and cooling sector.
Sungen, Jaca and Geetit participate in FocalStream project to industrialize a novel product based on HCPVT technology and to train the critical stakeholders for test, installation, operation & maintenance.
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 has been realized to summarize the progress done
In 2013 the German Fraunhofer Institute analysed the LCOE of different utility levels power production technologies, forecasting that CPV will be competitive with traditional PV panels by 2020, with a cost of 0.06 to 0.10 €/kWhe in 2020 and 0.045 to 0.075 €/kWhe in 2035.
Focalstream is able to anticipate significantly the energy costs forecast by Fraunhofer analysts: our target is to produce electricity in the 0.04 to 0.065 €/kWhe range before 2020 with a BASE plant, lower costs are possible with DUAL.
The Focalstream electric performance will improve with time as a consequence of the improving performance of the multi-junction cells. The project target power is 3 kWe, but we expect to reach 3.5 kWe when the first commercial version of the system will be sold, and up to 5 kWe in 2022.
The high yield means reduced spaces are required to generate a given amount of power. A typical 1000 m2 supermarket requires 350 MWhe/year to run its electric loads: to cover 70% of these loads with a PV system, circa 3000 m2 of land are needed, while with Focalstream 1000 m2 (the roof) would suffice.
Focalstream progress is beyond state of the art in what follows:
• High performance of primary and secondary optics;
• Usability of generated heat, whose temperature level is adequate for most uses;
• Interface with standard inverter;
• High level design of concentration modules;
• Scalability. Mirror fabrication process is scalable, we are working on the cell montage and soldering process;
• Competitiveness. The system cost is right from start, and there is room for future cost reductions.
Dense array HCPVT is a new technology: the possibility to share the costs of the tracking platform on a dual energy production, halving the cost of each one, is a relevant advantage of Focalstream over past CPV/HCPV products.
The Focalstream project is based on leading edge technologies and multi-disciplinary competencies, required to reach conflicting targets such as high performance and low cost.
The market potential of the system is high, if target performance is reached and price is right. A new sector of solar industry could be born, initially with moderate numbers, then significant ones. In our perception, the HCPVT route opened by Focalstream is a significant breakthrough
Frontal view of the Focalstream receiver
Focalstream Base version