A new system has been patented that can preheat water for baths and showers, as well as radiators while generating electricity. More than 50% of domestic energy use within the UK is heating water.
The system will utilize heat pipes which are superconductors of heat energy. These heat pipes can be found in devices from PCs all the way up to the International Space Station, where they prevent melting, from the heat of the sun, on one side and the other side from freezing in the vacuum of space.
Brunel’s Institute of Energy Futures, Dr. Hussam Jouhara explains, “As a professional engineer with a long-term research interest in heat pipes I could see many advantages in applying this technology to a renewable energy system.” He continues with, “Until now there was no system which fully addressed all the technical and practical issues that face making an entire building’s roof a solar-powered generator of both heat energy and electrical energy.”
Dr. Jouhara sees heat pipes as an obvious solution to issue that solar cells have when generating electricity.
“PV panels have an inherent challenge to the engineer,” he said. “The more intense the sunlight the more electricity the cells will produce, but only a fraction of the sun’s energy can be turned into electricity.
“So the sunnier it is the more of that unusable energy hits the cell which, in turn, heats it up. As PV cells heat up their electrical generation ability is degraded. Heat pipes, in this case, constructed in flat panels 4m x 400mm, will whisk that away to heat domestic hot water.”
PV cells that were cooled by Dr. Jouhara’s methods were able to outperform identical panels by up to 15%. They were also almost able to harness the full spectrum of energy the sun produces.
The installation of solar panels on conventional roofing has faced many difficulties, but the new system will address many of these problems.
“What was needed was an engineered, systems approach,” said Dr. Jouhara. “Our solar panels are PV coated for the most southerly facing aspect of the roof and are designed to clip together as a weather-tight roof as simply as clicking together laminate flooring.
“When we constructed our test roof using standard “off-the-shelf” roof trusses, tradesmen were able to quickly and easily screw together the panels with no extra guidance than a simple set of written instructions.
“The heat pipe technology also turns the biggest downside of integrating solar panels into conventional roofs into a positive.
“Currently the panels would get hottest in the summer and roofs need to be designed to dissipate that heat. Simply insulating the house below is not a good solution as that simply traps it driving up the PV panel temperature and further lowering its performance. With our system, there is no waste heat.”
The solar roof is in extensive trials at the Building Research Establishment (BRE) located in Watford. A prototype is currently powering a 3 bedroom detached house that is standard in the UK.
The research has already found an unexpected event, “Our flat heat pipes are so efficient that they can actually capture the energy from early morning dew evaporating off the trial roof,” Dr. Jouhara added.
Credit: Image courtesy of Brunel University