FWIW.
No power anywhere near the strip. Plane Rans S6 with Rotax 912. Sunlight trickle charger has worked for two years now.
A solar cell on the shed roof with lead down to feed a/c battery via croc clips onto the Live +12 V behind the key switch and -ve to metal airframe. Find the live terminal with a light bulb or voltmeter.
It's too feeble to overcharge (smile).
In the Summer it is re-routed & charges the grass cutting tractor battery for easy starting.
mike