New hybrid solar panel roof slashes energy bills

September 25, 2015, Brunel University
Dr Hussam Jouhara with his prototype hybrid solar panel

Scientists at Brunel University London have designed a new hybrid roofing system which could halve energy bills in new homes.

The patented new system harnesses a unique mixture of technologies to pre-heat domestic hot water for radiators, baths and showers while also generating electricity. More than half of domestic use in the UK is to heat water.

At its heart is the use of heat pipes – super conductors of - found in high tech devices from PCs to the International Space Station where they prevent it from melting in the heat of the sun on one side and freezing in the vacuum of space on the other.

Dr Hussam Jouhara of Brunel's Institute of Energy Futures, who led the British team which developed the new system explained: "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".

"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."

Heat pipes seemed to Dr Jouhara an obvious solution to a major technical issue with solar cell or photovoltaic (PV) panels used to generate 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."

In proof of concept tests, PV cells cooled by Dr Jouhara's methods outperformed identical panels by 15 per cent. And rather than being wasted, almost the full spectrum of energy from the sun is harnessed.

The new system also addresses a wide range of practical issues in installing solar panels in new properties.

Attempts to integrate installing solar panels with conventional roofing techniques have a poor track record.

"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 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 ."

The solar roof is now undergoing extensive further trials at the Building Research Establishment (BRE) in Watford where a prototype is powering a standard UK three-bedroom detached house.

And already there has been one unexpected finding. "Our flat are so efficient that they can actually capture the energy from early morning dew evaporating off the trial roof," added Dr Jouhara.

Explore further: Hybrid solar cell converts both light and heat from sun's rays into electricity

More information: "The performance of a novel flat heat pipe based thermal and PV/T (photovoltaic and thermal systems) solar collector that can be used as an energy-active building envelope material," Energy, Available online 3 August 2015, ISSN 0360-5442, dx.doi.org/10.1016/j.energy.2015.07.063

Related Stories

October was 'bumper' month for Scotland's renewables

November 7, 2014

Any way you look at it— the solar PV panels, the solar hot water panels, the wind turbines—Scotland turned out to have a bumper month for renewables in October. Wind turbines generated an estimated 982,842MWh of electricity, ...

Yale engineer to build 'hot' solar cells

September 22, 2014

Associate professor of electrical engineering Minjoo Larry Lee has been awarded $2,540,000 to develop dual-junction solar cells that can operate efficiently at extreme temperatures above 750 degrees Fahrenheit. In addition ...

Recommended for you

Late to the party, German carmakers join race against Tesla

September 23, 2018

After years watching Tesla's electric cars speed ahead while they have been on the defensive over an industry-wide diesel emissions scandal, German high-end manufacturers have finally unveiled their first challengers to the ...

4 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Jeffhans1
5 / 5 (4) Sep 25, 2015
If you build heat exchanging and storage systems into the yards of homes with these, you could store the excess for use in heating the homes in Winter. My dad has two solar heating panels on our roof and it provides enough hot water in the summer to allow 17 people to get hot showers without getting cold. That was the most extreme test of it so far, but normal daily use doesn't come close to exhausting it.
MR166
5 / 5 (2) Sep 25, 2015
Solar water heaters were very popular many years back. Some how they have all been removed and I don't see new ones being installed. I don't know why that is and suppose they are not cost effective.
cccccttttt
5 / 5 (2) Sep 26, 2015
How about running the heat pipes to a Stirling Generator or over thermo electric cells.

In the heat of summer people want to run air conditioners, not take hot bathes.

ct
Dug
5 / 5 (1) Sep 28, 2015
"Hybrid solar panel roof slashes energy bills" Typical of most paid content today - there is zero information in the article that justifies or confirms the title statement. Consequently the title is misleading, deceiving and untrue. There no actual comparison data presented, no economics are reported, efficiency tests aren't defined and it is impossible to determine from the content of the article whether it would have an economic benefit or not. Is this phys.org or PR.org?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.