Reference Rief AG, Opfenbach

The Rief family’s farm is managed by Ludwig Rief, the fifth generation of the family to run the business, and is not far away from Lake Constance in southern Germany. As is typical of the region, dairy cattle are a staple of the business, but the company has several sources of income. The farm’s business model is rounded off by 80 hectares of pasture-land, 19 hectares of forest, the breeding of sows and hog farming for local distribution. However, the business has a further objective. “Our self-sufficient supply of energy is based on our values of sustainability and a circular economy,” explains Rief.

An important factor in this case was the presence of two photovoltaic systems that have been on the grid for quite some time. In addition to the 600-square-metre system on the pigpen (capacity: 205 kWp), there is another PV system (70 kWp) on the roof of a more recent barn building. “The two panel systems currently provide around 25 per cent of our power consumption,” states Rief. “Our biogas plant, which we’ve been supplying with slurry to generate electricity since 2022, represented a major step forwards. We still buy some residual power but should manage to achieve full energy self-sufficiency soon – at the latest, when we commission the 450 kWp PV system that we’re planning for our new animal welfare pigpen.”

Farm manager Rief has long been plagued with power losses from the PV systems caused by dirt on the solar modules. In some cases, electricity yields fell by 30 per cent. This problem was solved by Ludwig Rief’s informative visit to the Agritechnica trade fair in 2019, where he discovered the iSolar System. At the trade fair, Kärcher demonstrated how to combine portable high-pressure machines that almost every  farm already possesses with iSolar components to form an economically attractive complete system to efficiently clean PV systems on the farm. At the core of the iSolar System are rotating brushes that are powered by water from the high-pressure machine in low-pressure operation. The iSolar brushes are secured to continuously extendable telescopic lances. “It was cool to see how even large solar panels could be effortlessly cleaned down to the last corner with the carbon extension arms,” says Rief.

While he was still at the trade fair, Rief took the decision to use the iSolar System in combination with Kärcher high-pressure machines to regularly clean his PV systems in an efficient and cost-effective manner going forward. This started in spring 2020 with an iSolar set that was precisely configured for cleaning PV systems at the farm in Opfenbach and is still in use today. To ensure high area performance and convenient working, the counter-rotating iSolar 800 double brush (working width: 80 cm) was combined with a 10-metrelong telescopic lance. This combination was suitable for every job! It was able to clean the large system (that has an output of 205 kWp) in just two hours – and with just a single operator. Cleaning the smaller system also went smoothly. In this case, the iSolar System was used from an elevated work platform due to the height of the roof. “With the iSolar cleaning system, we’ve hit the jackpot and have quantifiably brought our PV systems’ yields back on track,” sums up Rief. “To ensure that the output remains the same, we’ve been systematically cleaning our solar panels every six months ever since – and therefore using the sun’s full power!”