Paxos unveils glass-glass PV tile with heat pump integration

Paxos Solar has developed a new glass-glass PV tile that integrates with heat pumps, featuring Longi’s back-contact solar cells. The 44 W, 59.5 cm x 48 cm tile can also produce heat for residential systems.

September 19, 2024 Cornelia Lichner

Image: Paxos Solar

From pv magazine Germany

Paxos Solar, a German building-integrated photovoltaic (BIPV) specialist, has developed a new solar tile that not only generates power but also produces heat for heat pumps.

The tile is a small glass-glass module measuring 59.5 cm x 48 cm and delivering 44 W of output. About 4.3 tiles would be installed per square meter, providing a total output of 190 W.

The modules feature highly efficient back-contact cells from China’s Longi. They are completely black on the front with a matte-structured surface that captures angled light. Paxos Solar’s technical director, Julian Münzberg, said the modules are produced by a partner in China.

“The flat solar tile is larger than other products on the market,” said Münzberg. “This speeds up installation and also enables more power on the surface. Connections to windows or chimneys can be cut to any size, and there is no need to use a complementary roof tile.”

The company uses the modules to create multi-energy roofs. It initially lays a layer of inexpensive trapezoidal sheeting over the insulation to serve as a dense, water-bearing layer. Next, it mounts support rails on top of this layer, into which they hang the glass roof tiles. Each tile features a glued rail on its lower edge for this purpose. The upper edge of the next module overlaps and presses down on the lower module.

Since the solar tiles do not overlap at the sides but are pushed together with a 1 mm gap, some water can seep through and drain off the trapezoidal sheeting.

The lower edge of the roof and the support rails, which run across raised beads, are perforated and allow air to pass through. When sunlight heats the air under the modules, it rises between the raised ridges towards the roof ridge and collects in a pipe.

“As soon as the temperature is at least one Kelvin above the ambient temperature, it is worth switching on the pipe fan integrated there and blowing the warm air to the heat pump,” Münzberg said.

The Technical University of Cologne tested and measured the concept, said Guido Schumacher, CFO and partner at Paxos Solar. The heat pump at the university required 20% less energy over the year compared to a similar device without the additional heat generation. The heated air was directed into the heat pump’s intake pipe, which was installed under the roof. For longer distances, insulated spiral-seam or stainless steel pipes can be used.

Schumacher said one square meter of the solar flat tile, including trapezoidal sheeting and mounting rails, costs €260 ($428). This means that 1 kWp equates to a material value of $2,308. Initial customer installations showed that setting up a multi-energy roof takes about half the time of a traditional roof covering and installation. The roof also weighs 31 kg per square meter, making it lighter than standard concrete roof tiles.

In addition to the black flat tile, Paxos offers PV beavertail roof tiles for listed buildings.

“There is a lot of interest in our roof tiles, especially from owners of listed buildings,” Schumacher said.

The company plans to install solar panels on about 200 roofs in the coming year. It is financing further growth through a crowd-investing campaign that aims to raise €1.2 million in 80 days. Investors can start with €100, and those investing more than €25,000 will receive company shares.

Paxos Solar is also behind a PV roof tile that Meyer Burger will sell and is currently putting into series production.

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