Solar Roof Tile Exhibition shows developments in photovoltaic roofing

by Rolf Hug

In an exhibition the company Biohaus PV Handels GmbH presents the history of solar roof tiles over the past 15 years. With its zero-energy office building the photovoltaic system integrator located in Paderborn demonstrates, since the beginning of 2005, versatile and innovative solutions for the integration of solar technology, including thin-film technology, photovoltaic façade elements and state-of-the-art high-performance solar cells.

Biohouse building with solar roof tiles on a monopitch roof.
A view of the Solar Roof Tiles Exhibition
Biohouse building with solar roof tiles on a monopitch roof, a view of the Solar Roof Tiles Exhibition. Photos: Biohaus PV Handels GmbH

"With the Solar Roof Tiles Exhibition we want to demonstrate that solar power generation is not only an ecologically sensible solution but that the aesthetic component is gaining in importance too,” Biohaus Managing Director Willi Ernst says when describing the purpose of the exhibition. The Solar Report presents the most interesting exhibition pieces, shows some of the systems already implemented and portrays the history of solar roof tiles from its earliest beginnings to the present, without claiming to be a complete presentation.

From a photovoltaic roof tile to a solar building component

Solar roof tiles are photovoltaic modules that are integrated into roofing. The individual “tiles” are linked with electrical plug-type connectors to form larger units and then deliver clean electricity. Solar roof tiles are being developed and sold since the early 90’s by different manufacturers to allow an optically attractive integration of solar roof tiles into the roof surface. Biohaus also manufactures solar roof tiles and has become the European market leader with its "BIOSOL InDach" system. And this was sufficient reason for the Paderborn company to present these special solar systems within the framework of an exhibition. Products of various international manufacturers are shown, including the Spanish module producer Isofoton and the Japanese manufacturer MSK. The performance of the PV modules included in the solar roof tiles has been significantly improved over the past years: from the initial modules with a peak performance of 3 Watt (Wp) per element up to 200 Wp in the largest solar roof tile offered by Biohaus today. This development is demonstrated in an exemplary and very vivid manner in the Eco-Park Exhibition Dören which is planned to be a permanent exhibition.

solar roof tile (BIPV sample IndustrieDach, 12 Wp, 1994) "Just Roof" by the Japanese manufacturer MSK solar tile "Isofoton teja ceramica".
Quantum leap: from the early solar roof tile (BIPV sample IndustrieDach, 12 Wp, 1994) via the "Just Roof" by the Japanese manufacturer MSK (82 WP, introduced in 1995) and the solar tile "Isofoton teja ceramica" (13,5 Wp, 2000) right up to the solar roof tile Biosol XXL (124 Wp, 2005).
Photos: Biohaus
Solar roof tile Biosol XXL .

Beauty comes at a cost

Solar roof tiles, in the narrow sense of the word, are conventional ceramic roof tiles with solar cells that are attached mechanically or with adhesives. In the broader sense of the word, this term is now also being used for solar roof tiles or solar roof elements that are manufactured from other materials, e.g. slate, plastics or metal. The aesthetically very attractive ceramic tile by Gebrüder Laumans GmbH & Co. KG with its head office in Brüggen was rewarded with great praise when introduced in 1999, especially since it allows a very sensitive integration of photovoltaics, even in buildings that are declared national monuments.

Solar roof tile.

However, the optically very convincing solution comes at a price: up to 25% additional costs for the tiles with mini modules of 3,75 and 4,55 Watt had to be calculated. To construct a system with a peak performance of one kilowatt, 400 tiles were required that were then equipped with linked mini solar modules. Particularly the cabling and the plug-type connections of the individual elements led to the price increase. Laumanns discontinued the production of its highly esteemed system on 31.12.2004, and other manufacturers of solar roof tiles had to follow suit.

The Swabian tile manufacturer Pfleiderer in Winnenden has also discontinued production of the “TerraPiatta-Solar” tiles that were introduced in 1999. However, production will be relaunched in autumn 2006. These solar tiles with a performance of 55 Wp each were assembled in a similar manner as the ceramic roof tile “Terra Piatta” and replaced six surface tiles each.
Solar centre in the Manor House Wietow (Mecklenburg) with TerraPiatta-Solar roof tiles and solar window shutters. Solar roof tile TerraPiatta-Solar by Pfleiderer.
Top: Solar roof tile TerraPiatta-Solar by Pfleiderer. Photo: Biohaus.Left: Solar centre in the Manor House Wietow (Mecklenburg) with TerraPiatta-Solar roof tiles and solar window shutters.
Photo: Martin Schachinger.
In spite of or possibly because of the solar power boom after the amendment of the renewable energy law in 2004, only very few roofs were tiled with the “classical” solar tiles during the past years. The trend moved towards larger solar power systems, even on private roofs. The cost-based compensation for solar electricity fed into the network led to supply bottlenecks for modules and solar silicium. Many maufacturers noticed that solar tiles moved into the background and the solar cells demanded were used for traditional modules to be mounted on roofs or to be used in ground mounted solar parks systems.
complete solar roofs by Biohaus.
Photo: Biohaus

The fact that solar building elements can compete aesthetically with conventional roofing is proven by the solar roof tiles by Biohaus. These high-performance Biohaus modules with thin-film technology based on UniSolar laminates and with black-coated profiles and assembly brackets replace conventional roofing and are utilised as complete solar roofs.

Clean electricity from beautiful roofs

Solar power systems on historical buildings or on buildings declared national monuments or on roofs constructed by demanding constructors have shown the possibility of sensitive integration of photovoltaics. This living proof includes the various solar tiles by European manufacturers that did not open a mass market but are a shining business card for solar power technology. The small-surface solar tiles on the basis of conventional tiles or on slate tiles were manufactured mainly by tile manufacturers who simply added the additionally purchased modules.

ATLANTIS-"SunSlate", 13,3 Wp, introduced to the market 1995. ATLANTIS-"SunSlate", 13,3 Wp, introduced to the market 1995.
ATLANTIS-"SunSlate", 13,3 Wp, introduced to the market 1995. Photos: Atlantis Energy Systems, Sacramento, USA.
The manufacturers of the modules, on the other hand, relied on high-performance solar roof tiles. PhönixSonnenstrom AG may serve as an example – this company used the Newtec solar roof tile developed in Switzerland, but had to discontinue production because of a lack of demand. According to information provided by the company, Newtec solar power systems with a total performance of 100 kWp were built – a marginal figure in comparison to the 1-Megawatt open-space system that Phönix built last year near Würzburg. Yet the Newtec solar tile is not to disappear entirely since the company certainly does see chances for the product and emphasises its aesthetic qualities.
Solar roof tile "Newtec" 0,864 kWp solar power system in Sulzemoos (left in pic.); right: solar heating system.

Photos: Solar roof tile "Newtec"; 0,864 kWp solar power system in Sulzemoos (left in pic.); right: solar heating system.


Source: Phönix Sonnenstrom AG

Houses with solar roof tiles can be found throughout Europe, occurring particularly frequently in Germany, Switzerland and Austria. The increased costs are justifiable particularly in historical buildings where conventional solar power solutions would not be authorised. But exemplary systems were also installed on new buildings: a solar roof in the Austrian town of Fußach (Vorarlberg) received the 2002 Austrian solar award by EUROSOLAR for its aesthetically successful and unobtrusive photovoltaic integration. The system boasts a performance of 2 kWp and forms part of the EU project "Hip – Hip” (House Integrated Photovoltaic - High-tech in Public).
Award-winning solar roof in Fußach (Vorarlberg). Award-winning solar roof in Fußach (Vorarlberg).
Award-winning solar roof in Fußach (Vorarlberg). Photos: Austrian Energy Agency

Experts and solar associations are expecting a further price reduction for solar modules through an expansion of photovoltaic capacities and the end of the current silicium shortage which could in turn lead to a renaissance of solar tiles. Whilst façade integration of solar power systems is rewarded by an additional 5 cents feed in tariff according to the renewable energy law, such an increased reward system has not yet been introduced for the integration of solar tiles. The rather small manufacturers surely were not able to form a strong enough lobby. Sensitive PV integration is supported and marketed by the German-Italian research project "PVACCEPT". The results of this project are published in the book "Solar Design" that was nominated the Solar Book of the Year 2005 on the Solarserver.

PV roofs are becoming larger, solar roofs also used for generating heat

A stroll through the 1. International Exhibition of Solar Roof Tiles at Biohaus reminds of times when the building of solar power systems not only made good economic sense but also required a fair amount of idealism. The system integrator in Paderborn opted for a combination of performance and optical appearance that also took into consideration financial aspects. The “real” solar tiles will probably be found in a niche market in future as well, whereas the trend towards the solar roof is continuing: the highly advanced assembly systems, e.g. "SolRif" or the XXL modules by Biohaus can be used for solar roofing on a large scale. This is proven by the solar power world record in the Hessian town of Bürstadt: the world’s largest PV solar roof with a photovoltaic performance of 5 MW was mounted on bitumen sheeting, protects the vapour barrier and minimises temperature fluctuations.

5 MW solar power roof in Bürstadt. Solar roof with 84 square metres of sun collectors for heat production.
5 MW solar power roof in Bürstadt. Photo. Tauber Solar Solar roof with 84 square metres of sun collectors for heat production. Photo: Sonnenhaus-Institut
Solar roofs that are completely covered with thermal sun collectors play an increasingly important role – for the effective support of heating systems or for houses that are heated with solar power only, large collector surfaces are required.

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