Solar swift recharger (SSR)
Please see the photos later of the process supporting this simple illustration..
SSR - (SolarSwiftRechager) cost nearly nothing...compared with a purchased one.......and can actually takes as many batteries as you like, but 2 kilometeres would be to stupid - the idal is between 1 and 7, and makes it a suitable length of pipe, and pleassen to handle..
Put the whole device outside in the Sun; that is also water-prof if you ensure to seal the minus end properly, then let the minus end direct upwards beside the small solar recharger cell - se photos later....
THIS IS ONLY a sample and a draft, - so, of course it can be done very nicely - and it works perfectly; she photo (i) when it is charging in the Sun light; and I actually did try it today.....working fine.....one whole hour's work; in additional to the brain work before sleep, oh, by the way, doing the invention before sleep, is a very good sleeping agent...
Alle the very best folks