Electrical currents will need to travel along a cable from the solar panels to the location where the electricity will ultimately either be used or stored for later usage (such as a battery back up system). Make sure the the cable you buy is the proper length and size for your DIY solar electricity product installation. If the cable is too skinny or thin electricity not only can be lost, but there is every possibly that the cable will burn out possibly causing a fire if the damage is bad enough. The cable is key because it connects the solar panels to a solar regulator or inverter.