Agri-photovoltaics: following the sun with zero lubrication

With an average area of three hectares and a capacity of almost 3MWp each, four agri-photovoltaic projects have already been completed and two new projects will be built by 2026. Eight to nine solar panels, each measuring 1.1 x 2.2 metres, are attached to a square tube and form a string. In the roofs already built, there are between 610 and 650 strings per project.

A string weighs almost a tonne and has to withstand wind speeds of over 130km/h. The pivoting movement is provided by one geared motor per string in conjunction with a pillow block bearing that holds the square profiles.

The bearing has to fulfil a number of requirements. Not only does it have to withstand the high loads, it also has to be as light as possible, corrosion-free and resistant to pesticides. To ensure trouble-free operation in both hot and cold conditions, it must also be temperature-resistant - and last but not least, it must be as low-maintenance as possible, as access at a height of five metres is restricted and would involve a great deal of effort.

Ball or plain bearings made of metal were therefore ruled out by the engineers from the outset. In particular, the need for regular lubrication, the associated operating costs and possible contamination of the cultivation area by lubricants were reasons for exclusion.

During the development phase, the developers at TSE quickly came across our maintenance-free products, which are already being used by other players in the solar industry. After receiving numerous samples and a lively exchange with our experts, the decision was made in favour of igubal ESQM pillow block bearings, which are specially developed for use in PV trackers.

The pillow block bearings are UV-resistant,corrosion-free and require no lubrication, making them dirt-resistant and completely maintenance-free. The housing and spherical ball are made of lightweight plastic and can be assembled quickly and easily thanks to their two-part design.The housing made of the robust long-fibre reinforced polymer G can withstand temperatures from -40 to +120°C without any problems.

In addition to these advantages, TSE appreciates the high static load capacity of up to 50kN and the angular compensation of 9°, which occurs in the application due to the slope.

In our igus in-house test laboratory, the ESQM bearing, simulated over time, achieved a service life of 72 years with a load of 1.5 tonnes. Therefore, igus guarantees a service life of 25 years.