SYCOMOREEN is showing you the electronics, the powering wires and the electrical protectors of the SMA 3000 TL-21 Multistring inverters, designed to bring solar photovoltaic energy on the AC 220V 50 Hz grids. br br For its inputs of direct current, the inverter gets 3 surge protectors Epcos ETFV20 Series, type K510 [near the yellow vertical strip], which are acting as thermal varistors to throw the overcurrents towards the Earth.