The thickness of active semiconductor part of solar cells spread from one to some hundred microns at most. These photo devices have to be packaged to protect them from damage and to make them rigid. A possible packaging construction is shown by Figure. The device is cased in plastic foil between two safety glasses. The front glass
provides protection and must have good transparency, the back glass serves as a holding structure and decreases the heat stress. There are metal plastic back layer devices, but in these cases the thermal expansion causes problems. The frame can be aluminium and other light metal. Fixing is done by these frames but there are photovoltaic devices without frame, too. Unit panels can be connected in series and in parallel, depending on the requirements. The form and size of unit panels depend on the solar cell technology (wafer, ribbon etc.), and it influences the image of the modules. The image of the solar module depends on the materials for colour and on the density and form of the collection electrode for morphology. The size of the module is determined by the size and number of the unit panels it contains.

Buildings are perfectly suitable for the placement of solar cells (Fig. 3.) [4, 6]. Solar cells can be looked at as a unit of building construction, which can be used well in architecture. Solar cell can be mounted on the flat roof to be used only for energy production and protection against radiant heat, having no other building construction

effect (Fig. 4.). The image of the building will not be influenced, because it cannot be seen from below. The weight of the wind and of the snow can be taken over simply by the holding apparatus. The only requirement is that the modules should not shade each other even at low position of the sun. Photovoltaic cells on the high — pitched roof and on the facade have aesthetical and building physical influence. It has been already mentioned about the dependence of the colour, form, size and morphology. Mounted solar cells give on the building surface an air shell, which in the summer protects against radiant heat and in the winter improves the thermal isolation of the roof. In case of mounting it on the roof both wind pressure and suck should be considered. A special roof tile which contains the holding apparatus must be fixed to the rafter. The relationship between the building tectonics and facade mounted solar cells is shown by Fig. 4. In this case the windows plain and the solar cell plain coincide. The distances betweenfloors of glass-only buildings can be used for energy production