Community Research and Development Information Service - CORDIS

  • European Commission
  • CORDIS
  • Projects and Results
  • Final Report Summary - NANOPHOSOLAR (Innovative, environmentally friendly nanophosphor down converter materials for enhanced solar cell efficiency that will reduce energy production costs and increase cell lifetime.)
FP7

NanoPhoSolar Report Summary

Project ID: 315677
Funded under: FP7-SME
Country: United Kingdom

Final Report Summary - NANOPHOSOLAR (Innovative, environmentally friendly nanophosphor down converter materials for enhanced solar cell efficiency that will reduce energy production costs and increase cell lifetime.)

Executive Summary:
Solar energy represents an almost limitless power supply globally if it can be captured and converted to useful energy. Solar electrical power is typically produced using Photovoltaic (PV) systems that are quiet and produce no harmful emissions or polluting gases. The Global installed capacity of photovoltaics (PV) was estimated to be 20,090 MW in 2009, with the EU representing 64.3% (12,926 MW) of these PV installations. The global PV market is projected to grow by 2050 to around 11% of global electricity production and thus avoiding 2.3 giga tonnes (Gt) of CO2 emissions per year. However, the EU is entering a new age and an uncertain energy landscape, with our dependency on energy imports increased from < 40 % of gross energy consumption in the 1980’s to 53.1% by 2007.
During the project a number of different tasks were undertaken.
A performance specification was produced for CIGS, CdTe, Si and DSSC Solar cells. A plasma process has been used to produce a range luminescent nanoparticles. Over the duration of the project, the material selection has been refined through assessing technical performance of the processed materials and Nanophosphor materials have been developed, with differing downshifting capabilities and different particle sizes. One Nanophosphor type has been produced reproducibly, in larger quantities with a defined particle size range. These materials have demonstrated, successfully, a downshifting capability. Additionally the Nanophosphors have been incorporated into a number of different coatings/encapsulants and investigated on a variety of substrates. Further work is required to provide demonstration of a net positive downshift in a fabricated photovoltaic cell. All new materials produced have had their excitation/emission data measured which has been subsequently provided to one of the RTD partners. A particle encapsulation development strategy was developed which could be readily incorporated into the plasma process in the particle collection chamber. Production scaling of the optimised doped particles has also been assessed
Process related specifications for the Coating Specification and testing procedures were determined. This included the coating manufacturing process and incorporation of the coating in the photovoltaic module. The mechanical performance specifications were also determined and included impact resistance, abrasion resistance and adhesion. The reliability and durability specifications were determined for accelerated aging according to IEC standards and cleanability. Testing procedures were also identified for optical and photovoltaic performance characterisation, cell power conversion efficiency, cleaning/abrasion resistance and accelerated aging.
Suitable resin materials for the initial coating formulations and encapsulant film within WP2 have been selected to enable their characterisation and laboratory test procedures for use in the development of the coating formulations have been established.
Polymer Film Specification and testing procedures were defined. These covered process related specifications, mechanical performance specifications, reliability and durability specifications and the associated testing procedures.
In the course of the phosphor dispersion development work, a 6-month storage stability study was carried out under the controlled conditions of 23°C, 50%RH on fully formulated UV curable coatings containing 5% loading of Ce:YAG particles and additional characterisation of the coating properties has been carried out.
In order to develop the nanophosphor polymer film modelling of the scattering properties of particles dispersed in the film took place.
For PV cell encapsulation and performance testing a procedure was defined to identify and quantify the down-shifting effect through EQE measurements.
A review of available polymer materials with a view to durability, reflection effects (refractive index effects), effects of particle dispersion (related to scattering properties) and processability of resins has been carried out.

Project Context and Objectives:
The NanoPhoSolar project aims to overcome the limitations relating to the efficiency and performance of a range of photovoltaic (PV) systems by developing a transparent NanoPhosphor down converting material capable of absorbing Ultra Violet (UV) and short wavelength visible light and re-emitting in the more useful longer wavelength visible spectrum(range 525-850nm). This will enable the efficiency of Photovoltaic (PV) cells to be increased by an additional 10% for silicon PV and ≥25.8% for Cigs or cadmium telluride PV and potentially increase system lifetime. By doing this, the PV system created will offer greatly improved environmental performance due to capture of a larger proportion of the incident visible spectrum. This will lead to significant economic and societal benefits to consumers and manufacturers. The SME consortium target a total in-process coating technology market penetration of 5.5% when applied in the manufacturing process and 0.25% when as applied to existing installed PV systems within a 5 year period post project, achieving direct annual sales of over €66 million, ~470 new jobs and annual CO2 emissions savings of 154,697 tonnes per annum. The project results are expected to benefit other SMEs in the PV and materials processing industry sectors.
Solar energy represents an almost limitless power supply globally if it can be captured and converted to useful energy. Solar electrical power is typically produced using Photovoltaic (PV) systems that are quiet and produce no harmful emissions or polluting gases. The Global installed capacity of photovoltaics (PV) was estimated to be 20,090 MW in 2009, with the EU representing 64.3% (12,926 MW) of these PV installations. The global PV market is projected to grow by 2050 to around 11% of global electricity production and thus avoiding 2.3 giga tonnes (Gt) of CO2 emissions per year .
However, the EU is entering a new age and an uncertain energy lanscape, with our dependency on energy imports increased from < 40 % of gross energy consumption in the 1980s to 53.1 % by 2007 . Currently, the EU27 meets 53.8% of its energy needs through imports. If no action is taken this will rise to 70% by 2020 . 45% of oil imports come from the Middle East and 40% of our natural gas imports come from Russia. Energy dependence poses economic, social, ecological and physical risks to the EU.
Although the EU leads the world in terms of in terms of market uptake, EU PV manufacturers are now threatened by imported technology from Asia and the US. China is now the largest PV manufacturing country in the world producing 3,800 MW in 2009 alone and was responsible for exporting €5442 million of PV cells into the EU 27 member states in 2009. A further €5100 million of PV cells was imported into the EU in the same year, whilst our own EU based production resulted in €4557 million of sales. Presently, only one European company features in the top 6 global PV manufacturers by solar cell production capacity.
In addition to these challenges, Europe has ambitious targets of securing 20% of overall energy consumption from renewable sources by 2020 and under the Kyoto Protocol the EU is required to cut its combined emissions of the six greenhouse gases to 8% below their 1990 level by the year 2012.
PV systems therefore provide massive potential to create renewable energy solutions in-line with the EU’s goals of reducing CO2 emissions and increasing energy security.

Our project directly addresses the needs of both the European Photovoltaic manufacturing sector and the European Photovoltaic installation sector. The EU PV sector has estimated annual sales of ~€6.5 billion/year and has approximately 6,000 SMEs, employing over 190,000 people. Both of these sectors will be the end-users of the technology: PV manufacturers will integrate the solution in to their new products and PV installers will fit the technology to their existing installations.
Our consortium is led by PRA, who have been chosen by the SME-AGs due to their extensive experience of managing collaborative projects. Within this project, the three SME-AGs will interact intimately to monitor, control and help direct the research effort to achieving the project’s objectives and milestones in a timely manner. Each of these IAGs represents members in other EU states.
• Bulgarian Photovoltaic Association (BVPA) very active in Austria and have created a national network to distribute information on PV and initiating various workshops and events. They have over 200 members.
• FEMETE is a private, non-profit, employer’s federations of companies in the Province of Santa Crux de Tenerife. It has over 1600 members operating in the various sectors from metalworking, ICT, waste management and renewable energies.
• Renewable Energy Association (REA) is a non-profit trade association, representing British renewable energy producers and promoting the use of renewable energy in the UK. The membership consists of over 950 companies ranging from sole traders, farmers, installers, energy suppliers, consultancy firms, training bodies etc.
Due to the growing environmental concerns about global climate change and energy security, European consumers are demanding cleaner renewable energy generation technologies. In recent years the introduction of Feed-in-Tariffs across the EU has made distributed renewable energy technologies more economically attractive. FITs put a legal obligation on utilities and energy companies to purchase electricity from renewable energy producers at a guaranteed favourable price. These FITs have supported the market development of renewable energy technologies, specifically for electricity generation. Feed in Tariffs have been particularly favourable for PV technologies in Germany and Spain and have been instrumental in the large scale uptake of PV modules in these member states. However, according to Reese Tisdale, Director of IHS Research , European governments are currently revising down their feed-in tariff schemes “in a domino like fashion”. These reductions in the FITs pose a potential threat to the continued high growth rates of PV penetration in Europe.
A recent of example of this has happened in the UK where the UK government has announced a 50-70% cut in the FIT for solar installations >50 kWp . The Micropower Council has warned that this may affect many organisations such as schools and hospitals and could make many of these larger community-scale solar schemes financially unviable. The curtailment of such schemes could stop the burgeoning solar photovoltaic industry in its tracks, the Council also cautions. “The proposed tariff reductions will affect investor confidence badly investor confidence in the sectors affected,” said the chief executive of the Micropower Council. Meanwhile, Mark Shorrock, chief executive of Low Carbon Solar, says the proposals are “nothing short of disastrous”, putting many schemes in jeopardy.
In addition to the revision of the FITs, the Global economic downturn has resulted in austerity measures within the EU. This has resulted in significant reductions in the rate at which alternative renewable energy technologies have been implemented. The flow of finance for renewable energy projects have been affected as the flow of debt form banks to renewable energy developers has dried up.
Therefore, although the increasing energy prices are acting as a driver for home owners and commercial organsiations to invest in renewable energy technologies, the macro-economic situation in the EU ( and globally) is making the investments more difficult to justify in terms of return on investment and payback. This represents a significant threat to our SME members.
Each of the AG associations within this project have recognised the need to further enhance our technology solutions by improving the efficiency and increasing the performance of the PV systems on the market. This will enable our community of SME members to increase the cost:performance characteristics of the PV systems they are supplying to the EU (and wider global) markets. If we are able to do this then we will greatly improve the value proposition and return on Investment for photovoltaic technologies, enabling us to redressing the negative effect of feed in tariff reductions and global economic down-turn.
Currently, there are two main limitations relating to current photovoltaic cells performance and their increased market uptake
1. The capital cost (€/kW) of the Solar PV systems limits the inherent return on investment. Presently, solar cells are priced typically in the range €1,370-4,500 / kWp installed capacity.
2. UV degradation of the PV systems lead to continuous fall in performance with time and limit the lifetime to <25 years. Presently, expensive cerium-doped glass or EVA formulations with UV stabilisers are used which block UVB radiation.
If our members can overcome these barriers then solar PV systems will become much more economically viable, that will lead to a step change in the cost of the electrical power generated and significantly increase the potential return on investment.

The overall technological aim is to develop an innovative down converter technology based on non-toxic, inorganic; long-life nanophosphors (produced using a novel nanomaterial synthesis method) that can convert high energy UV and short wavelength visible light (in the range 400-512 nm) into useful visible wavelengths (525-850nm) that are more readily absorbed by the photovoltaic (PV) cells and thus harvest more of the available solar radiation. This will improve efficiency and significantly reduce UV degradation for photovoltaic electricity. The individual objectives are:

1. To develop an enhanced understanding of the relation between the properties (particle size, morphology and stoichiometry) and performance (low wavelength absorption and re-emission in the useful visible spectrum) for nanophosphors with particle size <40nm.
2. To develop a more complete understanding of the nano-material processing parameters including cooling rate, gas flow, energy input and reactor shape, on the material stoichiometry, particle size and morphology of the nanophosphors.
3. To synthesise and characterise one or more novel optimised encapsulated nanophosphor (mean particles size 5-40nm) with an emission peak in the range 620 – 680 nm and absorption of > 60% of the UV and blue spectrum at AM1.5 in the UV spectral range λ= 200nm – 400 nm.
4. Develop a coating consisting of homogeneously dispersed nanophosphors in with no agglomerations > 100 nm and a shelf-life of 6 months that is compatible with coating technology.
5. Develop coating formulations (based on the homogeneous dispersions) and method of application for both existing silicon devices and thin film technologies at the point of manufacture suitable for coating glass and other component materials (in the case of the thin film technologies) to provide the following performance characteristics:
• Good adhesion to surfaces;
• Good UV stability;
• 90% optical transmission in the range 300nm – 880nm;
• Down conversion of >50% of the UV spectrum (100nm to 400nm) into the visible spectrum, centred on (initially) key silicon PV absorption at 550-750nm;
• Good in-can stability: > 6 months shelf-life;
• Durable coatings with stable down-conversion properties.
6. Develop polymeric films containing a homogeneous dispersion of nanophosphor material and method of application for retrofitting of existing in-field silicon PV devices to provide the following performance characteristics:
• Good adhesion to surfaces;
• Good UV stability;
• 90% optical transmission in the range 300nm – 880nm;
• Down conversion of >50% of the UV spectrum (100nm to 400nm) into the visible spectrum, centred on (initially) key silicon PV absorption at 550-750nm;
• Durable polymer films with stable down-conversion properties.
7. To undertake photovoltaic performance testing and determine long-term stability for ‘in-field’ and ‘in-production’ PV modules in a variety of climate or conditions to provide data to determine the endurance and electrical output in comparison to untreated modules.
8. Develop an exploitation plan to deliver enhanced value to team SME’s
• Identify cost / performance potential, defining cost advantages and cost per watt
• Identify 5 key markets and 5 key opportunities
• Identify and action suitable dissemination event at one of the RTD performers before the end of the programme
• Produce a final report by Month 36

Project Results:
A performance specification was produced for CIGS, CdTe, Si and DSSC Solar cells. A plasma process has been used to produce a range luminescent nanoparticles.
During reporting period 1 a number of Nanophosphor materials have been developed, with differing downshifting capabilities and different particle sizes. One Nanophosphor type has been produced reproducibly, in larger quantities with a defined particle size range. These materials have demonstrated, successfully, a downshifting capability. Additionally the Nanophosphors have been incorporated into a number of different coatings/encapsulants and investigated on a variety of substrates. Further work is required to provide demonstration of a net positive downshift in a fabricated photovoltaic cell.
Process related specifications for the Coating Specification and testing procedures were determined. This included the coating manufacturing process and incorporation of the coating in the photovoltaic module. The mechanical performance specifications were also determined and included impact resistance, abrasion resistance and adhesion. The reliability and durability specifications were determined for accelerated aging according to IEC standards and cleanability. Testing procedures were also identified for optical and photovoltaic performance characterisation, cell power conversion efficiency, cleaning/abrasion resistance and accelerated aging.
Suitable resin materials for the initial coating formulations and encapsulant film within WP2 have been selected to enable their characterisation and laboratory test procedures for use in the development of the coating formulations have been established.
In the course of the phosphor dispersion development work, a 6-month storage stability study was carried out under the controlled conditions of 23°C, 50%RH on fully formulated UV curable coatings containing 5% loading of Ce:YAG particles and additional characterisation of the coating properties was carried out, such as coating surface hardness.
Polymer Film Specification and testing procedures were defined. These covered process related specifications, mechanical performance specifications, reliability and durability specifications and the associated testing procedures.
In order to develop the nanophosphor polymer film modelling of the scattering properties of particles dispersed in the film took place.
A review of available polymer materials with a view to durability, reflection effects (refractive index effects), effects of particle dispersion (related to scattering properties) and processability of resins was carried out in addition polymer composite development trials were also done
For PV cell encapsulation and performance testing a procedure was defined to identify and quantify the down-shifting effect through EQE measurements.
Patent searches have continued and been reported; however a number of possibly relevant patents have been found and are being reviewed by the consortium for their consideration and further analysis. No patents were discovered that should prevent exploitation of NanoPhoSolar
Partners have been active in dissemination activities and a poster: Theoretical study of photocurrent enhancement in solar cells by inorganic down shifting phosphor materials was presented at the European Materials Research Society (EMRS) Spring Meeting Conference, May 2015, Lille, France Conference
An abstract was accepted for: European Photovoltaic Conference and Exhibition (EU-PVSEC), September 2015, Hamburg, Germany. Poster: Nanophosolar project: photocurrent enhancement in photovoltaic modules by inorganic down shifting phosphor materials
3G Solar attended and contributed to 3 exhibition/conferences and IML and REA attended and contributed to two exhibition/conferences.

Potential Impact:
The majority of photovoltaic systems are based on crystalline silicon solar cells, which accounts for ~90% of total, demonstrating efficiencies from 14-18% in production. Current PV production is dominated by single-junction solar cells based on silicon wafers due to wide availability and proven reliability. These ‘first-generation’ single-junction, silicon wafers are largely based on screen printed based devices. These devices are relatively expensive due to significant manufacturing and material costs; but they achieve the highest efficiencies on a commercial scale.
There are many limitations of solar photovoltaic technologies: high manufacturing cost result in high energy production costs, requires a shock absorbing encapsulation material between glass layer and module, intrinsically limited to poor efficiencies due to the limited range of absorbing wavelengths and no commercially available thin films technology harvests ultraviolet light energy.
As a result of these limitations, it is currently understood that cost reduction for silicon solar cells is the key to short-term uptake of photovoltaic power generation. The NanoPhoSolar technology can be adapted to be applicable with each of these cell technologies and architectures, down converting the UV light and upgrading the output of each module. Theoretical work has clearly shown that if we can achieve optimal size for the nanophosphor and homogeneously disperse this in a host matrix then we should be able to minimise size and optimise the refractive index so as to minimise scattering and to provide internal reflection suitable for light channelling into the solar cell. By designing the architecture of the solar PV module so that the incident light must pass through it before it goes into the PV cell should enable us to achieve an efficiency increase of ~10% for Silicon and ≥25.8% for Cigs or cadmium telluride PV systems.
Although the EU leads the world in terms of in terms of market uptake, EU PV manufacturers are now threatened by imported technology from Asia and the US.
Europe has ambitious targets of securing 20% of overall energy consumption from renewable sources by 2020 and under the Kyoto Protocol the EU is required to cut its combined emissions of the six greenhouse gases to 8% below their 1990 level by the year 2012.
Our project directly addresses the needs of both the European Photovoltaic manufacturing sector and the European Photovoltaic installation sector. The EU PV sector has estimated annual sales of ~€6.5 billion/year and has approximately 6,000 SMEs, employing over 190,000 people. Both of these sectors will be the end-users of the technology. PV systems therefore provide massive potential to create renewable energy solutions in-line with the EU’s goals of reducing CO2 emissions and increasing energy security.
Although the increasing energy prices are acting as a driver for home owners and commercial organisation’s to invest in renewable energy technologies, the macro-economic situation in the EU (and globally) is making the investments more difficult to justify in terms of return on investment and payback. Currently, there are two main limitations relating to current photovoltaic cells performance and their increased market uptake
1. The capital cost (€/kW) of the Solar PV systems limits the inherent return on investment. Presently, solar cells are priced typically in the range €1,370-4,500 / kWp installed capacity.
2. UV degradation of the PV systems lead to continuous fall in performance with time and limit the lifetime to <25 years. Presently, expensive cerium-doped glass or EVA formulations with UV stabilisers are used which block UVB radiation.
If these barriers can be overcome then solar PV systems will become much more economically viable, that will lead to a step change in the cost of the electrical power generated and significantly increase the potential return on investment.

Principal contacts:

PRA David Cartlidge D.Cartlidge@pra-world.com

Bulgarian Photovoltaic Association Desislava Lesova d.lesova@bpva.org

Federacion Provincial de Empressarios del Metal Y Nuevas Tecnologias de Santa Cruz de Tenerife Desiree Brito Rodriguez dbrito@femete.es

Renewable Energy Association Stuart Pocock spocock@r-e-a.net

Managess Energy Canarias S.L.U Isabel Bethencourt isabel.bethencourt@managess-energy.com

Hanita Coatings RCA Ltd Shai ben Tovim shai@hanitacoatings.com
Eurofilms Extrusion Ltd Nick Smith NickS@eurofilms.com
Quality Additives Ltd Kevin Sheridan kevin@qualityadditives.com
3G Solar Photovoltaics Ltd Barry Breen bbreen@3gsolar.com
Intrinsiq Materials Ltd Richard Dixon richarddixon@intrinsiqmaterials.com

Fundacion Tecnalia Research & Innovation Oihana Zubilaga oihana.zubillaga@tecnalia.com

AIDO- Asociación Industrial de Óptica, Color e Imagen Natividad Alcon NAlcon@AIDO.es

Reported by

PRA TRADING LTD
United Kingdom
Follow us on: RSS Facebook Twitter YouTube Managed by the EU Publications Office Top