(CN) – By 2050, many homes and apartments in Switzerland may be able to generate enough solar energy to meet their own consumption needs – including the charging of electric vehicles, according to a study released Wednesday.
While fossil fuel emissions plague the globe, reducing our reliance on them is a major focus of efforts to mitigate climate change. Photovoltaics, including the widely known solar panel, offer a promising alternative to fossil fuel consumption that could also increase energy self-sufficiency of individual households.
“We investigated whether it would be technically and economically feasible for households in Switzerland to achieve energy self-sufficiency using photovoltaics together with electricity storage. A prerequisite for this is electrifying the major household energy uses: heating and cars,” said co-author Ursin Gstöhl.
Solar panels work by taking two slices of semiconducting material, usually silicon, and giving it with both a negative and positive charge to create an electric field. These cells push out electrons of atoms into the metal surfaces surrounding them and electric power is produced. They have become the most cost-effective source of electric energy in high potential regions.
Photovoltaic energy is also produced through thin-film solar cells, which are only a few micrometers thick, making the technology very lightweight and portable. These are ideal for products that will be carried around and possibly handheld. The third and most expensive type of photovoltaic technology is III-V solar cells, able to conduct electricity much more efficiently and power devices such as unmanned aerial vehicles.
Research continues to develop new forms of photovoltaic technology for a wide array of uses; in the midst of today’s climate crisis, it can’t come a moment too soon.
“Solar energy is already being implemented on a large scale, but for households to be able to truly supply their own energy (i.e. be self-sufficient to the extent that they would disconnect from the electricity grid), they also need a way to store electricity given that the sun doesn’t always shine,” co-author Stefan Pfenninger explained. “This electricity storage can be done over hours to days with batteries and for longer-term storage with hydrogen.”
While several studies in the past have explored ways households can produce their own energy, this is the first to instead take a big-picture view of photovoltaic potential in a temperate country like Switzerland. Gstöhl and Pfenninger of ETH Zürich published the details of their new study in the open access journal PLOS ONE on Wednesday.
Switzerland is one of the most innovative countries when it comes to solar energy, having built the continent’s largest solar power station and the world’s largest off-grid solar panel system on the roof of a sports stadium. Unfortunately, solar power has not yet come to its full potential at a national level, though the Swiss still produce more solar energy than many Mediterranean countries.
“Globally speaking, a temperate climate is one of the least ideal situations for this: the productivity of solar power is less than in sunnier parts of the world, and energy demand in the generally cold and dark winter is higher than in summer, so energy is needed when solar power is least productive,” Pfenninger said. “However, our results show that even from this less than ideal starting point, many types of single-family households could likely be self-sufficient.”
While there has been a rise of solar panel installation in single- and multi-family homes over the past few years, they have yet to integrate into industrial or artisan buildings. According to the Federal Office of Energy, if solar panels are installed on the surface of every building that would benefit from solar energy, Switzerland could produce around 67 terawatt-hours a year (where a single unit is equal to one thousand watts per hour), compared to the 1.9 terawatt-hours recorded at the end of 2018.
To bridge the gap, Gstöhl and Pfenninger analyzed the technical and financial feasibility of energy self-sufficiency for households that switch over to electric vehicles and photovoltaic electricity to power all their needs, such as heating and cooling. By looking at readily available data, the researchers explored a range of different building types and current energy demands.
“Our study analyzes households on the dimensions of size, age, occupant behavior, and car use patterns. With these four dimensions we tried to cover a wide range of today’s housing situations for a country like Switzerland,” Gstöhl said. “In all cases, buildings are equipped with solar rooftop and facade PV, a heat pump, and electricity storage systems. The most crucial factors are the PV efficiency and the solar irradiation.”
Gstöhl and Pfenninger say total energy self-sufficiency is technically feasible by the year 2050 for single- and multi-family buildings in Switzerland across a range of scenarios. On one hand, it would be relatively easy for single-family households to change their behavior to lower energy demand and become self-sufficient. On the other hand, a multi-family building with conventional energy demand and calls for more research and advancements in the efficiency of photovoltaic technology.
“The big difference between single and multi-family homes is that single-family homes have more surface area available per inhabitant to put up solar panels. So it’s generally easier for these buildings to supply their own energy needs from their own solar system,” Gstöhl said.
Furthermore, the predicted financial feasibility of self-sufficiency depends on several factors, including government incentives and the cost of energy storage technologies. Fully self-sufficient buildings are more expensive than buildings that are fully electrified but connected to the grid, but so are households that still use fossil fuels for heating and in vehicles. In other words, the study conclusively shows that electrification is economically beneficial for households, with self-sufficiency coming at an additional cost premium.
“Doing many of the things you would need for buildings to become energy self-sufficient BUT remaining connected to the grid makes most sense. So, putting up solar panels, potentially with some battery storage, electrifying heating with heat pumps, replacing gasoline cars with EVs, looks like it will be cheaper than sticking to the status quo,” Gstöhl explained.
Regardless of the price tag, the combination of falling storage costs, rising fossil fuel prices, and political measures could ultimately result in an increased prevalence of fully self-sufficient households in Switzerland. These promising findings could also be applied to other highly industrialized countries with temperate climates worldwide.
“If the potential of being self-sufficient with photovoltaics can already be reached in a moderately sunny country like Switzerland, other sunnier regions could benefit even more from these opportunities. Given that measures to reduce greenhouse gas emissions globally are urgently needed, it is good to understand the extent to which homeowners could contribute to this goal and in the long term even save money while doing so,” Gstöhl concluded.
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