A solar roof tile is similar to a photovoltaic panel that converts sunlight into electricity. However, its appearance as a roof tile allows it to be placed on the house without demanding any additional space or interfering with its aesthetics. 

Although multiple companies offer roof tiles as an option, integrating them with a heat pump is an innovative approach that we haven’t seen before. 

Paxos Solar’s roof tile

Work began over two years ago on developing a solar roof tile that integrates with the heat pump. Paxos partnered with the TH Koln University of Applied Sciences to build a prototype tile that could generate electricity and heat. 

The team considered multiple factors, such as temperature, optical losses through scattering, environmental influences, and safety, while building the prototype and tested it extensively at the university in real-world conditions. 

In their preliminary studies, the researchers found an increase in the heat pump’s coefficient of performance by almost a quarter. This also varied depending on the heating requirement and the weather conditions. 

How does the system work? 

Nearly two years after their study, Paxos Solar has unveiled solar tiles commercially after partnering with China-based Longi to produce back-contact cells. 

The tile is entirely back on the front and has a matte surface structure to enable the capture of angled light. Each module measures 23.45 inches (59.5 cm) X 18.89 inches (48 cm) and has an output of 44W. 

With just five tiles installed, a house can generate up to 190 W in about 10 square feet of roof space. Paxos has also purposely designed the tiles to be a bit larger than other offerings in the market to ensure faster installation and greater power outputs from each tile. Additionally, connections to chimneys and windows can be made to any size, and complementary roof tiles are not needed to complete the installation. 

For installation, the company uses inexpensive sheeting above the insulation as a water-bearing layer. Support rails are installed above this sheeting, and glass roof tiles are glued to these rails during installation. 

The lower edge of the roof and support tile are perforated and allow air to pass through. Sunlight heats the air under the modules, then rises toward the roof ridge and collects it in a pipe, a PV Magazine report said.

When the air temperature rises by one Kelvin (1.8 Fahrenheit), the pipe fan is switched on, and the warm air is pushed into the heat pump. Another study conducted by the University of Cologne found that the heat pump supplied with such air needed 20 percent less energy over one year compared to a device that did not get additional heat from the solar tiles. 

Paxos Solar also states that installing its solar tiles takes half the time of a conventional roof installation and is much lighter.