SEMI-AUTOMATIC ELECTRO HYDRAULIC ACTUATION SYSTEM FOR THE MECHANISMS OF A MACHINE FOR WASHING PHOTOVOLTAIC SOLAR PANELS

In the world there is different sistems for washing the photovoltaic panels installed in solar power plants [1]. It is known that dust deposits, or other kind, on the panels may decrease energy production even up to 50%. Are known different dedicated machines or robots for washing of the PV panels. The authors of the paper presents the realization of a type of original installation which may be mounted in a 4x4 pickup truck, together with a water reservoir. The installation consists of a frame on which are mounted: oil tank with electro hydraulic equipments (valves), hydraulic pump driven with combustion engine, water reservoir, an arm with washing brush and automation cabinet. To automate the installation, the software is implemented as a state machine using UML standard language. The automation module was realized with a microcontroller, which receives signals from various sensors and which send electric commands to the solenoids of hydraulic valves, through high side switch ICs. The operator has at his disposal a remote control that communicates with automation module via serial standard RS232. For a washing process with good productivity, were implemented a series of automatic sequences. One of the sequences is rotating column in working position, to the left or the right, followed by unfolding the brush. Afterwards the operator approaches brush to the appropriate distance from the PV panel, then washing starts automatically. During washing the distance between brush and the PV panel is maintained constant automatically. When one row is completed washing stops and the operator, by pressing a button, starts the sequence of bringing the brush in the position where the pickup truck can move to the next row of panels. This sequence folds the brush, then the column rotates to bring the brush along the car. The article also presents the main tests of functionality of the machine, which demonstrates its utility. This type of mobile installation, which can be mounted on a 4x4 pickup truck, is an affordable solution for entrepreneurs who want to provide services for washing solar panels or for owners of solar plants with photovoltaic panels.