In Switzerland, about 6% of all apartment buildings have a solar hot water system (solar thermal) in operation. These are used to heat hot water in order to reduce the consumption of oil and gas. Most of these systems were installed about 10 years ago, when photovoltaics were much more expensive. However, in recent years they have been forgotten. Many owners and administrators discover the installations only by chance through a view of the property on Google Maps, when they analyse the roof for photovoltaic suitability.
On average, solar hot water systems have 20 years of operation ahead of them, during which they can generate CO2-free heat and also significantly reduce utility costs thanks to fossil energy savings. Because nobody knows about the existence of many installations, one in five is defective. This means valuable solar heat is being wasted and fossil fuel heating systems are having to step in instead.
Several cantons have already recognised the problem and launched awareness campaigns to make owners, caretakers and administrators aware of the issue. The free solartest.ch platform has been created for this purpose in collaboration with Energie Schweiz and Swissolar. This allows users to check whether their system is running correctly by simply entering the temperature values they have read.
To avoid having to read the temperature values every week, Energie Zukunft Schweiz has developed the LORALARM monitoring system, which can be retrofitted.
As part of a project with a large Swiss insurance group, 65 existing solar hot water systems were monitored, of which a total of 15 systems were found to be out of order. Minor repairs enabled systems worth CHF 1.5 million to be put back into operation within a very short time.
The good time to find out if your solar thermal system is running is on a sunny winter’s day. This ensures that the defect will be producing sun-warmed water again by the time of the productive spring days from the beginning of March, after any repairs have been carried out.
