The next leap in solar energy is already underway: photovoltaic-thermal roof tiles for your home

It depends on where you live and especially on the height of your house, true, but if you look out the living room window it is quite likely that one of the things you see most around you is roofs. There are large, small, irregular, better or worse preserved, low or high. Regardless, the point is that we can probably use them for more than just covering buildings.

That is the idea with which a German team is working, determined to get all the energy out of the roofs of houses. And not with common photovoltaic panels that you may not be able to —or want— to use for regulatory or aesthetic reasons. What they propose is to use solar roof tiles.

The company Paxos and the TH Köln University of Applied Sciencesboth located in Germany, have joined forces to develop a prototype of photovotaic-thermal tiles (PVT), devices capable of generating electricity and heat. One of the peculiarities of their design is that, except for the color, they are hardly distinguishable from conventional tiles, which could make them a reasonable option for those who are reluctant to fix large solar panels on their homes.

Get more out of rooftops

“Many roof surfaces in Germany are not used for power generation, although they would be an important element for the success of the energy transition. We want to create an offer for listed buildings and people who have so far refrained from solar energy due to its appearance”, Julian Munzberg points out., PaXos project manager. With the aim of polishing its prototype and advancing its development, the firm launched the Solardachpfanne (solar roof tile) project.

The idea is to offer an alternative to those who refuse to install panels on their roofs for aesthetic or legal reasons: “An optimized solar tile that generates electrical and thermal energy”. And all, emphasizes TH Köln, with a mosaic that “is barely distinguishable visually from normal tiles.” The prototype was developed by PaXos and improved by the German research center.

During more than three years TH Köln researchers specialized in areas such as renewables, photovoltaics or electronics dedicated themselves to improving their prototype. Among other questions, they looked at how it responded in different environmental conditions or its response to temperature.

Heat pump that uses the air preheated by the system.

During the process, the experts also analyzed the glass of the prototypes to minimize optical losses due to reflection or scattering, the best combination of solar cells and how to achieve maximum performance. To take advantage of the temperature generated by the plates, they also installed a coupled heat pump that uses the preheated air that uses it as a supply.

“The adjustments we made significantly improved physical properties and energy performance,” celebrate christian dick, from TH Köln. During the tests, the team also verified that the installation, in addition to providing energy, contributes to heat supply of a building.

The tests carried out for eight months —between March and October—, subjecting the tiles to real conditions, also produced good results. “The system showed comparable values ​​in electrical performance to a reference system with conventional solar modules”, point.

Image of the panels used during the tests: on the right, the system with the mosaic of solar tiles; to the left another formed with conventional panels.

Solar modules can be moved so technicians can walk over them.

For cool solar cells A duct was also added that contributes to improving its operation in a similar way to the rear ventilation of conventional systems. “Comparable performance can be expected,” Dick stresses. Now PaXos would have sold the patents related to the solar tile to a specialized manufacturer for mass production.

Recently, two other firms, Autarq and Creaton, also German, presented a design for solar tiles made up of a flat, smooth support that houses the photovoltaic pieces and is protected by 3.2-millimeter safety glass. “The system has a modular structure and is therefore perfectly suitable for complex roof surfaces,” points out Florian Scherr, from Creaton, in statements collected by PV Magazine. Its operating temperature ranges from -40 to 85 ºC.

Images: Technology Arts Sciences TH Köln