I'd never buy a helmet again without replaceable batteries, you end up with a disposable helmet. I picked up one of the cheap Harbor Freight units years ago that had the solar panel on it. It also had some non-replaceable batteries in it. Not sure if the solar panel was really supposed to charge the batteries or just supply the darkening current when you were welding but after a year or two it wouldn't darken properly with TIG but OK for MIG. The instructions about putting the helment into darkness really doesn't make sense. I used to lay my HF one out in the sun hoping it would charge the battery but that never happened. Then it wouldn't work at all unless you put it up to a strong light source. If you feel like fooling around with most of them you can open them up and either replace the batteries or put some external battery holders on it. Although I did play around adding the batteries it's not a worthwile exercise. I thought about getting a very nice helmet but couldn't decide where to drop my 250-350 dollars so I picked up another inexpensive one (Rhino Giant View) from an Ebay seller. The nice thing about it other than it's only $80 is that it does have easily replaceable batteries and it's got a nice big window, 3.93” x 2.64”. I like it because I can keep my no-line bifocals on and still get a clear view.
Just a hobbyist so it's worked well for me. If I used one everyday I'd probably pop for one of the more mainstream helmets that folks have been recommending.
Gary
200 DX, ThemalArc 250, Century 130 MIG
HF 8x14, HF Mill, Delta drill press and a bunch of power, air and hand tools...