Q Does increasing the length of the cable cause a corresponding decrease in charging efficiency?
A Yes, there is a small drop off however this is offset if you're able to get the panel in a sunny south facing location. We recommend using no more then one extension cable, so 8m in total (5m with the panel as standard).
The Evo36 & Evo56 comes with 5 metres of cable between the light unit and solar panel, but you can add an extra 3m to that with this Evo Solar Panel Extension Cable.