Due to a change of inverter location I need to lengthen some 4mm dc cables. These are run in plastic flexi conduit. No space for adding mc4 connectors and a junction box or dc switch would be difficult. Is it acceptable to crimp a butt joint and double heat-wrap over the joints? Each one will be staggered so separated from each other, and kept neatly within the flexi conduit. Any thoughts anyone?