Junction Box Empower yourself This is an important part of the solar panels. The junction box is an enclosure on the module where the PV strings are electrically connected. A PV junction box is attached to the back of the solar panel (TPT) with silicon adhesive. It wires the 4/5 connectors together and is the output interface of the solar panel. With the use of a junction box, it becomes easy to connect the solar panel to array. Usually cables with MC4 / MC5 connectors at the end are used. Most photovoltaic junction boxes have diodes. The function of the diodes is to keep the power flow going in one direction, and prevent power from feeding back into the panels when there is no sunshine.