On August 24, Dmitry Yakovlev, the Director of Solartek, presented the report “Integrated Photovoltaics (BIPV) for the Plus Energy Building and Smart City technologies” at the conference “Modern Energy-Saving Technologies in Megacities” within Days of Moscow at the Expo 2017 in Astana.
In his report, Dmitry Yakovlev stated the following main points:
- Currently, we may consider two types of technologies that can be applied for the integration of solar modules into facades: these are traditional solar cells and flexible thin-film elements.
- Traditional silicon solar cells are highly efficient (with the efficiency factor of 19.5% to 22%), but their use is paid back only under ideal conditions. They are heavy (20-25 kg/m2), rigid, and dramatically lose their efficiency in the absence of direct sunlight. These drawbacks restrict the use of traditional silicon solar cells in the cities.
- Due to their low weight and high flexibility of modules, thin-film solar cells can be integrated into curved surfaces, even those with low load-bearing capacity. Being less effective than crystalline silicon under ideal conditions (8-17%), thin film cells are much more tolerant to shaded areas and cloudy weather. As a result, their total energy output is 15-20% higher.
- Some new technologies for traditional modules like “n-type mono-c-Si” have an exceptionally high potential for the implementation of “solar facades” due to the fact that all the fittings are arranged on the rear side of the cells (i.e. MWT and IBC technologies). Such cells look more like elements of the building finish than traditional silicon solar cells.
- The lightest (0.6-1 kg/m2) and thinnest (0.5-1 mm) serial BIPV-ready products now use the technology of flexible cells based on amorphous/microcrystalline silicon (α-Si/μc-Si) and organic photovoltaics (OPV), however, their implementation is restricted by low efficiency (8-12%) and high price (€1.6-5/peak watt).
- More than a hundred companies already offer standardized solutions. BIPV product manufacturers are being differentiated between glazing, warm and cold facades, tiles (modules of reduced surface area), large sections for roofs and facades, integration into the roofing material, integration into the fencing and decorative elements.
- Thus, the greatest benefit can be expected from the integration of technologies: the Plus Energy Building concept can be implemented through an optimal combination of various BIPV-products based on different technologies.
- The implementation of the Plus Energy Building concept requires an optimized complex solution. In each case, a proper balance should be maintained between the aspects of architecture, aesthetics, energy and economy.
- To maximize the energy output of a plus energy building, the following scheme would be appropriate: traditional silicon BIPV products with maximum performance should be installed on the roofs, south facades, and other areas under direct sun rays; glass-based thin-film cells – on west, east, and north facades, as well as areas of shade and ambient light; flexible thin-film cells – on curved surfaces, surfaces with low load-bearing capacity, and small architectural forms.