Solar collectors

People have been trying to exploit the energy of the sun for a long time. These days, with solar thermal energy and photovoltaics, the technology is available to make this possible.

Solar collectors convert the sun’s rays into energy. Depending on what the energy is to be used for and what technology employed, various types of collector can be installed: glazed flat plate collectors (mostly on roofs), unglazed, coated collectors, evacuated tube collectors or hybrid collectors. Glazed flat plate collectors are the most common. These generate energy for heating water and supporting heating systems. Once installed on the roof, they can be expected to last around 25 years – with no significant further investment or maintenance work.

What benefits do solar collectors offer?

The biggest advantage of solar energy is obvious: sunlight comes to us for free, everywhere, and will continue to do so for a long time. It is not subject to price fluctuations, and remains unaffected by any conflicts within global markets.

Solar energy does not cause unwanted by-products such as carbon dioxide, now notorious as a pollutant emitted as a result of burning fossil fuels. It also requires no disposal sites, where the waste from conventional energy production methods sits, emitting toxins and radiation. No transportation, and therefore no oil tankers leaking into the ocean.

In short, solar collectors are probably the most ecologically sound means of energy production that we currently have. What’s more, the Swiss government wants to encourage more solar energy and has promised to provide subsidies for new installations. So – quick, get a few solar collectors put up on your roof?

What are the drawbacks?

Of course, solar energy also has a darker side – literally. Roofs that don’t get much sun, low-lying clouds over the Swiss Plateau, and the winter season cannot be argued away. And in the evening, the sun clocks off for the day. In the vast majority of cases, consumers will still have to rely to some extent on energy from the mains in addition to the energy from their solar collectors.

Concerns about the financial side are also not without foundation. While solar equipment has become less expensive, prices are still a fair bit above the costs of traditional heating systems.

What can solar collectors provide?

To provide one to two homes with water, you need solar collectors covering approximately 4 m2 to 9 m2 on the roof, as well as a hot water tank, connecting pipes and a control system. This should generate around two-thirds of the hot water required by one household per year. If the aim is for solar energy to contribute to the heating as well (up to 30% of heating energy required annually), the amount of solar collectors needed rises to approximately 11 m2 to 16 m2 of collector area.

The costs

For a compact system using glazed flat plate collectors for heating water for a single-family home, you’re looking at costs of between CHF 15,000 and CHF 20,000. If the system is to be used not just for hot water but for heating the house, too, the amount climbs to CHF 25,000 to CHF 30,000. Anyone interested in this type of system should also be prepared for additional costs of more than CHF 10,000 compared to traditional heating systems. However, as the system produces energy, which therefore no longer needs to be bought elsewhere, and as you can also benefit from government subsidies, over time the amount is substantially recouped, meaning heating costs get closer to those of conventional systems.

Are solar collectors worth it?

In terms of the planet, reducing your ecological footprint will always be worthwhile, but in financial terms, the question of whether purchasing solar collectors will pay off does not have a straightforward answer.

A system will make more or less sense depending on the location and the type of house (south-facing roofs, with a pitch between 15° and 60°, are most suitable for solar collectors), as well as the decision to install solar collectors in various positions on the house, thereby increasing the system’s efficiency. The place of residence will also be a factor. While some cantons or even cities (such as Bern) are promising generous incentives, others are proving more stingy.

But for anyone who has to renew their heating anyway, it is definitely worth considering what your energy might look like in the future. Making sure your new heating system is capable of being retrofitted with a solar energy system is a good idea in any case.