The first prototypes of the solar roof tile
The systems which are currently available on the market include a further receiving system which is typically installed (raised) on a roof already covered with roof tiles, which then receives panels (solar power or solar heat). The "disfigurement" and the insufficient use of the roof surface are (in addition to the installation costs of such a "double roofing") the serious disadvantages of this system. The usage of a solar roof tile instead of a "normal" roof tile is a quite obvious solution. However, it requires a very efficient design to be able to mount these solar roof tiles quickly and easily on the existing roof battens with different lath spacing. It also requires a roof system, which guarantees the supply and discharge of the fluid (in case of solar heat) and electricity (in case of solar power - also called photovoltaics). We have developed this roof tile and roof system and have patented them in three different patents. Our solar roof tile has the same dimensions and the same weight as comparable roof tiles made of clay, but is considerably more stable, more durable, walkable and storm-proof.
Astonishingly easy and quick to use is the "snap-in system", with which a roof can be covered just as quickly as a roof with normal roof tiles.
Please do not hesitate to contact us if you are interested in this project. We will gladly give you an insight into the development as well as the essential patent bases.
The chain of tiles with "snap-in system". Due to the length variability, the tiles fit to the normal slat dimensions (the distances of the slats vary by up to 10% depending on the length of the roof and the number of tiles, so that an integer number of tiles can be covered uncut)
Cut through a roof surface with paXos combi solar roof tile
The feeder is located where usually the s.g. "gutter board" is (it is almost a placeholder under the last row of tiles - right in front of the gutter)
The collector leads via the ridge (below the s.g ridge tile)
Details of the "snap-in system" with the movable mounting
Calculation and simulation of heat dissipation
Here is the first hand sample of the paXos combi solar roof tile without cover glass and with cut open absorber sheet in order to be able to look into the inner workings.
Same opening, but looking at the "snap-in system" with the double-acting rotary vane safety mechanism. With this rotary vane (red), the solar roof tile is fixed on the roof batten and the slot nut (not shown here) is secured in the slot nut holder (yellow). By turning the screw on the front, the roof batten and in another position the snap-in system can be triggered. Thus, each roof tile can be removed from the roof surface in case of need and can also be reinstalled.
On the front there is another screw head (next to the one for the rotary vane), with the help of which you can screw any solar roof tile to the roof batten (here below left, right next to the red rotary vane end).
Performance data (for a combi solar roof tile):
- 4 wafers (12.6 cm x 12.6 cm) each with 0.6 volts MPP voltage and 4.1 watts peak
- 1 absorber (33 cm x 30 cm) with heat exchanger
- thus 16.4 watts peak electric per solar roof tile (SCT)
- thus 30 watts peak thermal per solar roof tile*
(* at 50 degrees Celsius temperature difference and 1000 W / m² irradiation)
- Visual dimensions of the solar roof tile at maximum coverage:
30 cm wide, 36 cm long / high
- A roof side of a saddle roof of a "typical" single-family house with 12 m roof width and 7.2 m stretched roof length / height would have:
40 tiles in width and 20 tiles at maximum coverage in height, so in sum 800 solar roof tiles
- the electric power would be 13.12 kW peak and
- the thermal power would be 24 kW peak
This energy yield in photovoltaics is actually achieved with the paXos combi solar roof tile, while conventional systems degrade in summer from 28 degrees Celsius with about 0.4% per further degree of heating, ie. often bring significantly less yield, because the cooling by rear ventilation is not sufficient.
Furthermore, during the "classic cooling" by rear ventilation the heat is not used but "thrown away".
Note 1: As a kind of "hidden performance", the paXos combi solar roof tile offers a much cooler attic in summer, which in turn requires no or significantly less air conditioning power.
Note 2: The performance data for the roof refer to a roof without dormer, skylight, antenna mast or similar.
However, such "yield-reducing" elements are less problematic with the paXos combi solar roof tile than with conventional panels because these elements can be bridged and need not be recessed with the area of an entire panel (or several).
Note 3: If in summer the photovoltaic is cooled to an optimum of 25 degrees Celsius in order to have the maximum yield, it will be cooled with a patented "cooling chimney" - more on that under the cooling chimney tab. But that would also mean that the yield in solar thermal energy would be correspondingly low. This can be remedied / changed by three things.
1. The last three to five tile rows could be designed with pure solar thermal roof tiles for "reheating"
2. A controller which deliberately allows a higher temperature (less cooling) for the charge of the buffer for some time
3. Additional heating with electricity in case of need (for showering, etc.)
Which of the three options (sometimes in combination) are used depends on the individual needs and the orientation of the roof surface.