Solar energy can be used to generate both heat and electrical power. Most solar panels are designed for only one of these purposes, so an electrical photovoltaic panel is typically no more than 20% efficient and will become hot when exposed to sunlight. If the panel is actively cooled by passing a fluid through the rear of the panel, it is possible to generate both heat and electrical power. This combined solar heat and power system is known as a hybrid Photovoltaic-Thermal (PV-T) collector and offers some advantages when space is at a premium and there is demand for both heat and power. By 2050 solar power is projected to deliver the majority of the world's electricity and will require much more efficient use of the premium, unshaded space that exists in the built environment. PV-T collectors are a highly efficient technology, capable of achieving system efficiencies (electrical + thermal) of over 70%. In response to this medium term opportunity, this research proposal develops optical nanostructured surfaces that enable an industrially manufacturable solar cell to become the ideal PV-T absorber. This is achieved by ensuring visible and near-infrared sunlight light is scattered internally within the solar cell, longer wavelength sunlight is absorbed and very long wavelength thermal emission is suppressed. The research employs state of the art computer simulation to design the nanostructured surface, followed by large area nanofabrication that can be performed using low-cost effective nanoimprint methods (the technique used to manufacture DVDs). The the suppression of thermal radiation is achieved using a low-emissivity surface which is also a low-cost process, similar to the 'heat reflecting' coatings that are applied to low-E glass used in energy efficient windows. The solar cell architecture employed is the Heterojunction Interface (HIT) solar cell pioneered by Sanyo and that recently set the world record for the highest efficiency silicon solar cell ever demonstrated. Remarkably, this solar cell can be manufactured at low cost and lends itself to structured coating owing to the unique heterojunction design. Importantly, this solar cell retains it's characteristically high electrical efficiency at high temperature making it ideal for PV-T applications. Prototype PV-T collectors that contain this optimised solar cell will be fabricated in this project and subjected to both indoor and outdoor testing. A predictive computer model will be established that reproduces the electrical and thermal output of the collector under both indoor and outdoor conditions. The model will be used as a basis to assess the applicability of the technology in various applications, especially those that demand relatively high temperature heat (100 degC) for which the system will be particularly well suited. The research will be disseminated in the scientific literature and conferences and also to a broader audience at workshops held at Imperial College and trade shows.

A 4-year multidisciplinary project aimed at minimising primary-energy use in UK industry is proposed, concerned with next-generation technological solutions, identifying the challenges, and assessing the opportunities and benefits (to different stakeholders) resulting from their optimal implementation. Around 20 companies from component manufacturers to industrial end-users have expressed an interest in supporting this project. With this industrial support, the team has the necessary access and is in a prime position to deliver real impact, culminating in the practical demonstration of these solutions. The proposed project is concerned with specific advancements to two selected energy-conversion technologies with integrated energy-storage capabilities, one for each of: 1) heat-to-power with organic Rankine cycle (ORC) devices; and 2) heat-to-cooling with absorption refrigeration (AR) devices. These technological solutions are capable of recovering and utilising thermal energy from a diverse range of sources in industrial applications. The heat input can come from highly efficient distributed combined heat & power (CHP) units, conventional or renewable sources (solar, geothermal, biomass/gas), or be wasted from industrial processes. With regards to the latter, at least 17% of all UK industrial energy-use is estimated as being wasted as heat, of which only 17% is considered economically recoverable with currently available technology. The successful implementation of these technologies would increase the potential for waste-heat utilisation by a factor of 3.5, from 17% with current technologies to close to 60%. The in-built, by design, capacity for low-cost thermal storage acts to buffer energy or temperature fluctuations inherent to most real heat sources, allowing smaller conversion devices (for the same average input) and more efficient operation of those devices closer to their design points for longer periods. This will greatly improve the economic proposition of implementing these conversion solutions by simultaneously reducing capital and maintenance costs, and improving performance. The technologies of interest are promising but are not economically viable currently in the vast majority of applications with >5-20 year paybacks at best. The project involves targeting and resolving pre-identified 'bottleneck' aspects of each technology that can enable step-improvements in maximising performance per unit capital cost. The goal is to enable the widespread uptake of these technologies and their optimal integration with existing energy systems and energy-efficiency strategies, leading to drastic increases performance while lowering costs, thus reducing payback to 3-5 years. It is intended that technological step-changes will be attained by unlocking the synergistic potential of optimised, application-tailored fluids for high efficiency and power, and of innovative components including advanced heat-exchanger configurations and architectures in order to increase thermal transport while simultaneously reducing component size and cost. Important system-level components are included in the project, whose objective is to assess the impact of incorporating these systems in targeted industrial settings, examine technoeconomic feasibility, and identify opportunities relating to optimal integration, control and operation to maximise in-use performance. A dynamic, interactive whole-energy-integration design and assessment platform will be developed to accelerate the implementation of the technological advances, feeding into specific case-studies and facilitating direct recommendations to industry. Only two international research teams are capable of developing the necessary tools that combine multiscale state-of-the-art molecular thermodynamic theories for fluids, detailed energy-conversion ORC and AR models, and incorporating these into whole-energy-system optimisation platforms. This is truly a world-leading development.