Free energy for your home

Sixty-seven terawatt hours of solar power for all?

The amount of solar energy that hits Switzerland alone is enormous. According to the Federal Office of Energy, around 67 terawatt hours of solar power could be produced annually on house roofs and facades - 10% more than current electricity consumption in Switzerland. But more is needed to achieve the Federal Energy Strategy 2050 goal of making Switzerland climate-neutral.

For example, the operation of buildings accounts for around 45% of Switzerland's total annual energy consumption. It is therefore necessary to insulate properties better and to heat them exclusively with renewable energies. Replacing oil and gas heating systems is the top priority – for instance, with a heat pump with a geothermal probe. This combination draws around three-quarters of the necessary heating energy from the ground. As you can see: Every single plot of land has renewable energy in large quantities – and completely free of charge at that.

Energy transition as early as 2035?

However, not all property owners are aware of the fact that they are sitting on almost inexhaustible energy reserves. The 2021 country comparison of the Swiss Energy Foundation dated June 2022 shows this. According to this study, in terms of production of wind and solar power per capita, Switzerland ranks 23rd out of a total of 28 countries in Europe. It is at least in tenth place in Europe in terms of solar power.

According to Anton Gunzinger, the overall poor performance of Switzerland is partly due to the fact that the potential of solar and wind energy has been massively underestimated for a long time. In the last decade, these would have become the cheapest energy sources in the world. The former ETH professor is the author of the book "Kraftwerk Schweiz – so gelingt die Energiewende" [Powering Switzerland – How the energy revolution succeeds] (2015). His appeal: "From now on, for every house renovation and every new building: insulate, install a heat pump, and install photovoltaics on the roof – both on the south and north sides."

Homemade power – photovoltaics

Those who want environmentally friendly electricity from their own roof, however, need a lot of patience at the moment. That is because the order books of installation companies are full; photovoltaics are booming. It's worth waiting for – many times over. A solar-based system is ecological, has a certain degree of independence from developments on the electricity market, and can increase the value of the property.

The storage of electricity from photovoltaic systems and wind turbines is a much-discussed topic. After all, how can energy be stored at night or during the consumption-intensive winter months? Batteries are getting cheaper and cheaper, but they are not very ecological due to their production being extremely energy intensive. On the other hand, it makes sense to use a battery that is already there – that of an electric car. Provided you have a model capable of "bi-directional charging." This means that it can store the electricity produced during the day and return it to the household in the evening.

Homemade hot water – solar thermal energy

The popularity of photovoltaics has put an older, proven way of generating solar energy on your own property on the back burner: solar thermal energy. The first systems of this type appeared here in the 1970s. In order to use solar energy for hot water or heating, collectors, a pump, and a storage tank are all that is needed – so the costs are manageable.

And how does it work? The water-glycol mixture circulating in the collector heats up by way of the black surfaces. In the basement, the heat is transferred to the water in the storage tank through a exchanger. This can then be used directly in the home or to support heating.

Homemade heating energy – Geothermal probe with heat pump

Deep beneath each plot of land, there is an almost inexhaustible source of energy. The heat radiation from the Earth's core ensures that at, a depth of 200 meters, there is a constant temperature of 15 degrees throughout the year. As a landowner, this reserve of energy can be tapped into with the help of a geothermal probe and a heat pump.

For this purpose, a glycol-water mixture circulates in the geothermal probe. This transports the heat from inside the earth upwards to the heat pump. The pump then removes the heat from the probe circuit by compressing and vaporizing the refrigerant contained in the device, thus generating water at a temperature of up to 55 degrees for heating. A geothermal probe has its advantages, even during hot summers: The heat generated in the building can then be transported to the ground via the probe.

The combination is proven: In 2021 alone, 3.5 million meters of geothermal probes were installed in Switzerland for the operation of heat pumps. The efficiency of the combined solution is so high that around four kilowatt hours of heat are generated with one kilowatt hour of electricity – so 75% of the heating energy comes from our own production. If the electricity for the operation of the heat pump comes partly from the house's own photovoltaic system, the level of self-sufficiency increases again.

Three technologies – many advantages

The three technologies (photovoltaics, solar thermal energy, and geothermal probes with heat pumps) demonstrate how the energy available on our own plot of land can be tapped into relatively easily with reasonable effort and proven technology. In addition, they make an important contribution to the transition to renewable energies.

The following tables compare these technologies and provide insight for interested property owners.