Solar energy potential at the Great St Bernard Pass

The historical site of the Great St Bernard Pass, situated in the Alps at an elevation of 2469 m, records very high electricity consumptions. This study aims at evaluating the photovoltaic potential at the pass. The analysis was performed on the envelope surfaces of the building complex, taking into account the topography as well as typical climate data issued from a weather station located on site. It is found that during the months from June to October, each year, 54 MWh of electricity could potentially be generated, which is more than what could be produced by the same system in the climate of Geneva.

Assessment of Solar Thermal Power Technologies

James Spelling

In the present climate of growing awareness about the dangers of global climate change, the development of new renewable energy technologies is primordial in the efforts to reduce emissions of carbon dioxide and other greenhouse gases. Rapid increases in the price of oil and worries about the stability and security of the extraction of fossil fuels have lead to renewed interest in the development of local energy sources, thereby reducing dependence on foreign fuel sources. Amid the plethora of option available, one of the more promising solutions is the increased use of solar power. Two main contrasting technologies exist for the conversion of the Sun’s energy into useful work, namely photovoltaic cells and solar thermal systems. The development of photovoltaic power has shown massive growth in recent years despite high costs, due mainly to the modular nature of the cells which allow their installation by private citizens, coupled with a number of government incentives. Development of solar thermal power generation has however been reasonably limited until recently, with the only continually operated commercial plants being the Luz SEGS I-IX plants at Kramer Junction in the United Sates. Solar thermal power generation shows great potential for supplying the base electricity needs of numerous countries in the sun-belt regions, stretching from the tropics to the Mediterranean. This has lead to a recent renewal in the development of such systems, notably with the construction of the PS10 central receiver plant in Spain. The Spanish government plans to bring the total solar generation capacity to a total of 300 MW by 2013. In other countries around the world, interest is growing in solar thermal power, with increased government and private spending fuelling research and innovation. Most solar thermal conversion technologies are still at the experimental stage, and no single technology has yet to impose its dominance. Different countries and research groups hold different solutions dear, but if solar thermal power is to become a fully mature electricity generating technology, the best of these diverse solutions must be combined in order to achieve optimal performance of the power plants.

2008

Active façades : life cycle environmental impacts and savings of photovoltaic power plants integrated into the building envelope

Gianluca Cattaneo, Angela Clua Longas

Goal Increased energy supply from photovoltaics is a main priority in the “Energy Strategy 2050”. Within the research project “PV2050: Sustainability, market deployment and interaction to the grid – the impacts of advanced photovoltaic solutions” funded by the Swiss National Science Foundation, we analysed different options for the enhanced integration of photovoltaic (PV) technologies into the envelope of Swiss buildings using novel monolithic silicon heterojunction organometallic perovskite tandem cells (SHJ-PSC) with adaptions to improve the visual acceptance. In a joint effort of product developers, architects and scientists, this project aimed at providing pathways for the wide-scale use of PV façade solutions, and developing integrated designs based on emerging high-efficiency module technologies to improve the visual aspect and acceptance of PV systems installed in Switzerland. These so-called active façades using photovoltaic modules to produce electricity can provide a significant contribution to the energy transition away from fossil and nuclear fuels. 2. Methods We compared the environmental impacts of different types of construction for building façades with and without integrated monolithic silicon heterojunction perovskite tandem modules (SHJ-PSC) with improved visual design using a prospective life cycle assessment with a time horizon of 2025. The comparison includes a conventional roughcast façade, a wooden façade, and two different active façades using photovoltaic modules. Furthermore, we compared the environmental impacts caused by the construction of the different façades with the environmental impacts saved due to the electricity produced by the active façades composed of photovoltaic modules. In addition, we analysed the reduction in environmental impact of the building using building-integrated photovoltaics due to substitution of construction materials for the façade or roof. 3. Results The use of photovoltaic modules as façade or roof will increase the environmental impact of the façade or roof compared to the use of conventional construction materials. However, the environmental impacts over the whole life cycle are significantly reduced due to the PV electricity produced by the building. The environmental impacts of the BIPV façade are about two to three times higher compared to a conventional façade, but the savings due to the electricity produced by the BIPV are five to eight times higher than the impacts of the conventional façade. The use of BIPV panels in the façade of buildings will cause net savings of about 600 kg CO2-eq per square meter over the whole life cycle of BIPV façades, while simultaneously saving 100 kg CO2-eq per square meter of façade for the reduced material demand.

2019

Reliable Averages and Risky Extremes

Annelen Kahl, Michael Lehning, Viet Anh Nguyen, Karine Maria Sarrasin

With the perspective of Switzerland’s phase-out from nuclear energy, solar energy potential may take a leading role for the country’s future in renewable energy. Unlike nuclear power stations, photovoltaic (PV) production is prone to intermittency as it depends on the immediate solar irradiance, which fluctuates in space and time. If a large percentage of Switzerland’s electricity was to be derived from solar radiation, stochastic fluctuations pose a risk to the robust supply and healthy function of the electricity network. For most efficient PV planning and siting, it is hence imperative to understand and quantify this variability in solar radiation, in order to anticipate average production as well as worst-case scenarios. Based on 12 years of satellite derived, spatially distributed data of daily average surface incoming shortwave radiation (SIS) this work analyses standard statistics, spatial correlation patterns and extreme conditions of cloud cover over Switzerland. Having compared different irradiance products, we decided to use the SIS product captured on the Meteosat Second Generation satellites, because it provides the most reliable snow/cloud discrimination, which is essential for spatial analysis over alpine terrain. Particularly in regions with high elevation differences, correlation between cloud cover and elevation undergo an annual cycle. In winter more clouds are found in the valleys, while in summer convective clouds dominate at higher elevations. The highest average irradiance values occur in the southern parts of the country, and make the cantons of Vallais, Tessin and Grison ideal candidate locations for PV installations. Simultaneously the Tessin shows a higher risk of periods with long lasting cloud cover, which would discourage from relying too much on solar power in that area. However looking at the question of suitability by studying spatial and temporal correlations of extremes, we see that the Tessin appears to be comparably decoupled from the rest of the country, and leads us to believe that this zone plays a valuable role in compensating temporary deficits in solar production from other regions of the country. This is just one of many example that highlight the complexity of spatio-temporal variability in solar irradiance and its implications for a reliable electricity supply in a future renewable Switzerland.

2016