A box for connecting an output conductor from a solar panel with a feed cable has a base mountable on the solar panel and formed with a first hole for the panel-output conductor and a second hole for the feed cable, a removable cover fittable with the base in a closed position and forming in the closed position with the base a substantially closed compartment, and at least one component mounted on the cover in the compartment. The component is something that affects transmission of electricity from the solar panel into an electrical network connected to the feed cable or that affects the microclimate inside the connection box.