Environment

Hybrid solar roofing system uses heat pipes to boost efficiency

Hybrid solar roofing system us...
The prototype hybrid solar system incorporates PV panels and flat heat pipes
The prototype hybrid solar system incorporates PV panels and flat heat pipes
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Dr. Hussam Jouhara, who led the research
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Dr. Hussam Jouhara, who led the research
During proof of concept tests, the scientists found that the pipes helped PV cells to cool by 15 percent more
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During proof of concept tests, the scientists found that the pipes helped PV cells to cool by 15 percent more
The prototype hybrid solar system incorporates PV panels and flat heat pipes
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The prototype hybrid solar system incorporates PV panels and flat heat pipes
The system can keep panels cooler and tap waste heat
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The system can keep panels cooler and tap waste heat
The flat shape of the heat pipes makes them easy to install
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The flat shape of the heat pipes makes them easy to install

You would think that the more sunlight that hits a solar panel, the better. When it comes to efficiency though, that's not the case – as photovoltaic cells heat up their efficiency decreases. To capture that heat and put it to good use, a team of scientists from Brunel University London has created a hybrid system that turns the whole roof into a solar generator.

The patented system combines flat heat pipes with PV cells to both heat water and generate electricity. Heat pipes are used to transfer heat away from surfaces where it's not wanted in various settings, such as personal computers, data center cooling, and even in space.

The flat heat pipes used are flat, measuring 4mm (0.4cm) x 400mm (40cm), which optimizes the collection solar radiation. Theses pipes heat water for use elsewhere as well as transferring heat away from the solar cells, which means their efficiency is not degraded to the same extent. During proof of concept tests, the scientists found that the pipes helped PV cells to cool by 15 percent more compared with a standard installation.

During proof of concept tests, the scientists found that the pipes helped PV cells to cool by 15 percent more
During proof of concept tests, the scientists found that the pipes helped PV cells to cool by 15 percent more

"Currently the panels would get hottest in the summer and roofs need to be designed to dissipate that heat," says Dr. Hussam Jouhara, a specialist in heat pipe technology who led the scientific team. "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 flat heat pipes also lend themselves to easy installation. "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," says Dr. Jouhara.

A prototype of the system is currently being tested on a standard three-bedroom detached house by the Building Research Establishment (BRE) in Watford.

Dr. Jourhara says they have already noted some surprising capabilities: "Our flat heat pipes are so efficient that they can actually capture the energy from early morning dew evaporating off the trial roof."

Source: Brunel University London

9 comments
Raven Bo
"capture the energy from early morning dew evaporating off the trial roof." Wording is wrong. It should be "it can capture early morning just when dew start to evaporate" IBM have mirror hybrid using gallium.
tacheonabike
4 house in the background with normal roofs and an experiment on the ground seems like an opportunity missed
Steve Jones
This always seemed like the obvious solution to excess heat, but there are issues. Firstly heat supply / demand, because excess heat is mostly produced when the building's heating system doesn't need any help and could therefor e only be used to heat hot water to come out of the taps, which is a sporadic demand. Secondly one of complexity/cost - for the cost of these heat pipes, you could have a bigger, more powerful solar array; which enhancement would prove more cost-effective long-term? I wonder if using the excess heat to boil a volatile liquid which then drives a turbine and produces more electricity would be a better solution.
Martin Hone
Surely evaporating dew is has a cooling effect ?
Douglas Bennett Rogers
Condensing dew releases heat, which is captured by the heat pipes and carried away to heating system. Evaporating dew will further cool the roof. Dew could run into gutter and provide distilled water. This is only good in the cooling season. Failed electrical connections only mean reduced power, while fluid leaks are a much bigger problem.
Nomadic4wd
This system is a copy of what is currently being manufactured and sold commercially in Australia. Not sure how they can claim a patent on it as it is obviously the same.
attoman
Every four or five years PV panels become more efficient while the range of use of a water based heat pipe is confined to limited parts of England and Wales. The hard freeze problems in most of Europe mean antifreeze with its attendant problems. All in all build truly modular panels and drive down cost of efficient ones this will do more then any cooling system (except one). As to the patents the basic idea of cooling the PV chip is in the public domain and available to anyone anywhere. I'm sure the good Doctor Jouhara being a heat pipe specialist has found some unique solutions involving heat pipes.
SchulteRoofing
The idea of using heat pipes for increasing the efficiency of solar roofing panels is very thoughtful and innovative. This is especially useful for houses with small roofs that are capable of only a limited number of photovoltaic cells. This way even a fewer number of PV cells will be able to satisfy the energy needs of a house.
Elias
The idea of storing solar heat in fluids has been around for decades. Pipes freeze sometimes, and they always leak. This idea might work on the roof of a garage or porch.