Awaiting Public Project Summary

Awaiting Public Project Summary

The SolarFAB project will develop a robust Concentrated Photovoltaic solar cell fabrication process on large 150mm substrates compatible with high efficiency multi junction solar cells operating at concentrations up to 1000 suns and current densities exceeding 10A/cm2. The project will develop robust top and bottom level metallisation processes and optimal current collection strategies with particular attention paid to minimise the cost and environmental impact of these stages. The metallisation for solar devices requires low contact resistance and solar shadowing, whilst optimising coupling of solar energy into the device with the aim of maximising the useful energy generated by the solar device. Different CPV cell producers use different lens concentrating arrangements e.g., creating a gaussian or uniform light distribution on the cell. The top level interconnects design strategies and Anti-Reflection Coatings will optimise conditions for the prevailing lens types. The key technical innovations are the development of such capabilities on triple junction 150mm substrates at a low cost, realising the competitive potential of CPV over other forms of photovoltaics. In recognising the growing importance of CPV in the renewable energy sector, the EU has recently announced the NER 300 project to develop a 20MWatts CPV system. A prime objective of the project is to place the project partners in an excellent position to supply CPV triple junction cell material/devices, putting the UK in a prime position to supply the solar renewable market, particularly regarding exports.

Concentrator Photovoltaics (CPV) are a potentially a cost-effective alternative to conventional flat-plate solar modules, due to the use of cheap plastic optics which concentrate sunlight. CPV cells have the highest photon to electricity conversion efficiency (46%) which can be further improved under optical concentration. The small size of standard CPV cells (0.3-1 cm2) potentially leads to very low electricity costs. However, the CPV cell temperature needs to be cooled to optimise power generation, currently done via passive (heat sink) or active (water cooled) systems, often inefficient or complex / expensive. Thermal energy (up to 50% of the incident photon energy) can be controlled effectively with reliable solid-state thermoelectrics (TE) technology, demonstrated at proof-of-concept at Cardiff University. This collaborative project brings together manufacturers of CPV epitaxy (IQE plc) and TE modules (ETL) with proven academic expertise in manufacturing electronic CPV-TE receivers (Cardiff Univ.), and lifetime & reliability testing (Bangor Univ.). The project outcomes will be optimized theoretical designs and manufactured prototypes of novel CPV-TE receivers, lowering costs of renewable energy generation and building the UK CPV supply chain via technical innovation.

Vertical-cavity surface-emitting lasers (VCSELs) are small, fast, cheap lasers with a low-divergence circular-beam profile. They are ideally suited for sending signals down the optical fibres that are used to carry the vast amounts of information that we take for granted every day. VCSELs are already widely available for generating light in 600 to 1100 nm range for datacoms applications, e.g. relaying information around a datacentre, but, because of the distributed Bragg reflector (DBR) technology that is the key to their operation, they are invariably GaAs-based. This has limited their use in telecoms applications, which requires longer wavelengths (1260 nm to 1675 nm): it has proven difficult to generate a GaAs-based active region that emits at telecoms wavelengths. In this feasibility study we will assess the potential for commercially-viable, GaAs-based VCSELs, that can operate cooler-free at high-speed and at telecoms wavelengths, by exploiting the novel self-assembled GaSb quantum ring technology developed in Lancaster in the active region of the device.