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Content archived on 2024-06-18

Competitive stationary low concentrating solar module of novel design

Final Report Summary - SOLGAIN (Competitive stationary low concentrating solar module of novel design)

Executive Summary:
Project SOLGAIN was a high-risk project form the very beginning, brought by the idea to gain the competitive advantage in the market of the upcoming BIPV products, by introducing competitive alternative for flat PV panels based on low concentration PV device.
Nevertheless, all the results expected have been implemented with just minor deviations by the end of the project. The expected technological achievement has been identified from Technology Readiness Level (TRL) 2 – 3 to TRL 6 – 7. The final results enabled reaching the TRL 5. By the end of the project, the project RTD partners have prepared the detailed recommendations for further results development which would allow reaching the desired TRL 6 – 7 in two years frame.

Project Context and Objectives:
EU is dependent on fossil fuel therefore the whole supply chain was developed to harvest the oil, gas and coal sources. As a result, economic growth and prosperity has strongly bonded to these sources, in a way that Community became vulnerable to energy supply disruptions from outside the EU, to volatility in energy prices and to climate change. In order to strengthen EU independence on external energy sources and achieve the European energy and climate change policy goals the development and deployment of a diverse portfolio of low carbon energy technologies had started. In 2012, photovoltaic (PV) technology was the leading renewable energy technology in terms of capacity growth in Europe. In total, EU PV installations took 55% (17.2 GW) of renewable energy sources.
High expectations for decrease of PV electricity generation costs and diminishing incentives, force PV players throughout the all supply chain to seek out, demonstrate and implement in production between 2013 and 2015 the innovative technological solutions for large scale deployment of PV. In order to penetrate fast growing and changing PV market and to get acceptance form value chain partners and public, the novel technology should address the cost performance, value of PV electricity, low initial capital costs, short energy payback, high technical lifetimes of overall system and, of course, to meet all the flexibility an integrality requirements.
The consortium has been created to face these kinds of economic, environmental and technological obstacles by proposing the SOLGAIN idea to develop the novel design for stationary low concentrating photovoltaic module (sLCPV) enabling achievement of 0.67 €/W cost target and optimized module assembly suitable for commercial applications.

This overall objective is divided into a set of scientific, technological and non-technological objectives targeted to overcome four fundamental obstacles of existing technologies:
• Small acceptance angle either leading to rapidly increasing aspect ratio versus the geometric gain, resulting in bulky systems or requiring the tracking system;
• Not sufficient optical efficiency, limited by commonly used material properties of primary and secondary optics and losses at interfaces;
• Not uniform light distribution over photovoltaic cells resulting in the hot spots therefore limiting the performance of concentrating photovoltaic (CPV) module;
• Required increase in solar cell efficiency. Cell and module efficiencies have a direct impact on the overall €/W cost (and price) of a PV module, an increase of 1% in efficiency alone is able to reduce the costs per W by 5–7%.

Therefore, the main scientific objectives of SOLGAIN project are:
• To develop transparent dielectric nanocomposite material with refractive index n > 2 required for secondary optics and ensuring wide acceptance angle at 5X concentration ratio;
• To develop and optimize the primary and secondary concentrator design and its assembling technique;
• To develop a high-efficiency (20% under one sun) back side interdigitated copper contact solar cell (Si wafer thickness <100 μm) for optimum performance in 5X conditions;
• To develop self-forming nanostructured antireflective coating for top surface of solar cell.

The main technological objectives of SOLGAIN project are:
• To develop the novel stationary sLCPV module within predetermined technology performance parameters;
• To test and validate SOLGAIN module in laboratory and to perform field evaluation.
The non-technical objective of the project is to perform business case validation for assessment of perspectives for SOLGAIN module and to develop the exploitation strategy.
The consortium combines know-how on concentrator optics, photovoltaic technologies (solar and module), testing and optimization of PV module. Contract research will be performed by Italian, Lithuanian and Spanish research institutions which provide a unique integration of know-how on stationary sLCPV module development.

Project Results:
The main activities and results of the project for the second reporting period consist of research and development done under the WP1–WP3 as well as dissemination and management activities.

WP1: the project activities started from definition of requirements and specifications for each of the key elements of the sLCPV module and for assembling of module. The work was performed successfully – the requirements and specifications were defined on the basis of theoretical date, SME requirements, EU standards, market needs and user expectations for the sLCPV module performance.

The main objective of WP2 is to develop a modified prism coupled compound parabola (MPCCP) solar concentrator by developing transparent high refractive index n > 2 dielectric nanocomposite material and the primary and secondary concentrator design. To this end, the nanocomposite material in film form with refractive index 1.97 at 580 nm was developed and the numerical simulation model for the concentrator was successfully implemented and applied for the preliminary design of the concentrator using the characteristics of the material as derived from the thin film development. On the basis of results achieved a bulk nancomposite material based on TiO2/PMMA was implemented but a refractive index of 1.62 at 580 nm was achieved which was not sufficient for the prism with desired properties. Since the adopted pristine approach has not met the objectives, an alternative solution has been implemented by means of nanofluid based on TiO2/Decane with a refractive index of 1.85 extrapolated by Fresnel law from the IR region, according to the indication obtained by modelling. It met the requested objectives and allowed to fabricate the concentrator prismatic secondary optics for further integration into device.

The activities in WP3 are targeted at the development of high efficiency solar cell with back-side interdigitated copper contact and self-forming nanostructured antireflective coating. During the research activities the solar cell routing card prototype based on computer simulation results was developed. The expected 20% efficiency of solar cell has not been achieved in existing technical facilities however, the comprehensive strategy for the reaching expected solar cell performance has been developed.
Optimization of technological processes as well as the new possibilities offered by the PROTECH technological facilities lead to quite optimistic result: the upgraded equipment and modified processes directly improved SOLGAIN BCBJ solar cell efficiency twice up to 13%. Solar cell prototype routing card based on computer simulation results were successfully made. Routing card improved through developed and iterations processes. Nano structuring was successfully realised. Corrective actions to improve solar cells and reach 20%+ efficiency were identified and 2 years plan for further development and transfer of the technology to potential customer of the SOLGAIN solar cell technology was prepared.

The main objective of WP4 is to assemble the novel stationary sLCPV module and optimize the assembling technique. A proof of the concept sLCPV module was prototyped by assembling solar cells, primary and secondary optic elements avoiding the efficiency losses in the module. The assembly of the proof of concept prototype was performed manually in the laboratory. The fully integrated prototype was submitted for full scale testing. On the basis of results achieved the recommendations for an automated assembly have been developed, taking in to account the possibilities of lowering the amount of parts to be assembled, weight optimization by an adequate material selection, accuracy of the systems needed to be within the tolerance setting for enabling the simultaneous enlightening of all cells in one row, the sensitivity to shocks, vibrations and thermal expansion.
The results achieved completely meet the objectives of the WP4: the initial assembly plan has been developed and documented. The sLCPV module has been prototyped and the assembly plan has been updated, however the fully integrated prototype has not been developed due to lack of module components performance. The assembling technique has been optimised for the proof of concept. In terms of assembling, the results indicate that the assembling is suitable but the improvements should be made in the future: prism, electrical connections and thermal management. The final results for fully integrated prototype will depend on each component. Several problems were indicated: degradation of secondary optics, high fragility of solar cells, not sufficient adhesion of fingers and electrical connections.

The main objective of WP5 was to test and validate SOLGAIN module in laboratory, perform field evaluation, and to prepare recommendations on module performance and assembling optimisation.
The results partially meet the objectives of the WP5. The testing has been done, but not all the IEC62108 have been tested due to the low amount of samples. Testing in the field has not been done due to timescale, no time for testing. All IEC62108 testing have been performed but only partially.

The main activities in WP6 were focusing on evaluation of the achieved project results from technical and economical point and on the preparation of recommendations for products up-scaling. More detailed, the activities of WP6 were covering surveying users of the foreground and other stakeholders by using structured questionnaires with open-ended and close-ended question as well as with project coordinator, SME contractors and principle researchers involved in the project to get their feedback regarding particular technologies developed in the project as well as product itself; establishing full view of novel products and planning the actions and resources required for the introduction to the market in the view of the basic trends in the solar energy technological sector.
The results achieved are in line with the objectives for this WP: questionnaire was successfully prepared and extensive survey was conducted through which SOLGAIN results from technical point of view were evaluated. A business case validation was implemented taking into account full view on novel SOLGAIN sLCPV design and alternative applications for SOLGAIN technologies, actions and resources required for the introduction to the market described. List of recommendations for further improvements of SOLGAIN technology was prepared.

The main activities in WP7 were focusing on dissemination and exploitation plans for the SOLGAIN results to ensure that the achievements of the project results are made known to the targeted potential clients and (or) market segments and to prepare plan for future exploitation of the project results.
WP objectives were achieved fully having implemented wide reaching dissemination agenda by fully operational project website from the very beginning of the project, visibility of SOLGAIN in various conferences and events. SOLGAIN project has been made known to specialized and general sectors of renewable energy, energy service and construction companies, consultants in emerging markets and etc., potential users were informed about the SOLGAIN products through the presentations in events, exhibitions and fairs, various related online networks and websites. The key events where partners were present were INTERSOLAR 2014, EUROREG-PV 2014, PVSEC 2013 and PVSEC 2014, Sol-Gel 2013, Photonics West 2014, OFTA 2014, SPIE Photonics Europe 2014. The Final Plan for use and dissemination of foreground provides a complete and cumulative overview of all dissemination and exploitation of foreground related activities.

Potential Impact:
Project SOLGAIN was a high-risk project form the very beginning, brought by idea to gain the competitive advantage in the market of the upcoming BIPV products, by introducing competitive alternative for flat PV panels based on low concentration PV device.
Energy generation by PV technology in the science world is being known as the research dense technology involving not only material but also IT, power electronics as well as mechanical research tasks. Concentrated PV also is adding to this list optical research issues. Due to this proposed SOLGAIN solution was complex research performed in parallel in several directions interacting in resulting product. Not all of the problems were foreseen in the start of the project this led to the situation where all the further developments were based on the initial start assumptions which were based on too low TRL available for particular technologies thus in some cases were too optimistic concerning possible to achieve final TRL.
The first nine months research results indicated main issues and problems to overcome to reach desired project objectives and consortium agreed to extend research activities according to the established plan to overcome technological drawbacks. During the 2nd project period this plan was implemented with significant success and even in the situation (secondary optics) when planned approach failed alternative solution was thought and implemented to allow prototype assembling and preliminary testing. Despite pure testing results RTD partners presented clear roadmap for further technology improvement, while SME partners managed to attract interest from possible investors for particular project results to uptake technology developed not only for PV market but also for other promising applications and products. Interest coming from stakeholders’ environment is demonstrating attractiveness of technologies developed for investors therefore consortium is confident in usefulness of the results achieved in the project for their future businesses.

The SOLGAIN project has several results that are commercially valuable and exploitable:
• Prism coupled compound parabola concentrator of wide acceptance angle. The novel design of prism coupled compound parabola has been developed for maximizing the annual energy production. The MPCCP concentrator with a high refractive index dielectric prism emerges as a viable solution for the realization of stationary planar sLCPV modules using silicon solar cells.
• Transparent dielectric nanocomposite material. The high refractive index of this material offers a double advantage by allowing: to reduce the concentrator aspect ratio leaving the geometrical gain unchanged, and to develop a fully stationary solar module without need of mechanical tracking of sun radiation.
• High efficiency back side interdigitated copper contact solar cell based on special design of solar cell with junction and contacts on the backside of cell. This design provides a possibility to eliminate shading losses, and to employ useful top surface for wide solar spectrum absorption. Moreover, this solar cell is of reduces costs with very thin contacts developed using electroless chemical deposition of low cost and high conductivity double layer of nickel and copper technology.
• Novel stationary low concentrating photovoltaic module will meet the market demands and address the following market needs:
o Cost-effective solution for achievement of high PV efficiency;
o Value of PV electricity (wide acceptance angle and high efficiency in the direct and diffuse light reason potential to generate the electricity during high energy demand hours);
o Lower initial capital costs (reduced energy, materials and time consumption in manufacturing and installation);
o Short energy payback time of PV system (less than 1 year);
o Flexibility in system design, ability to combine PV components and systems and integrate them with building components, especially in the vertical facades.

The project has contributed to SME participants’ competitiveness with the following:
• Unique selling points – the new stationary low concentrating photovoltaic module, c-Si back-contact solar cell and optical concentrator will be developed and delivered to the market at a competitive price in 1–1.5 years.
• Market penetration – the novel product sold directly the residential and commercial sectors, meeting the growing market demands. The new markets will be developed in Members States where the initial cost of PV system has been a key market barrier and therefore, the PV market is only in launch phase.

List of Websites:

Further information about SOLGAIN project can be accessed online at http://solgain.eu.