Exactly
The solar battery gets it power from welding not ambient light.
The cheap ones work fine but IMO your helmet should be conditional on the work you do.
Welding laying under a car you need an auto helmet because there is no room to "flip" a regular helmet.
For TIG weldin you will need an expensive auto helmet, the cheap ones are not sensitive enough and will flash off and on during welding.
If you do a lot of MIG welding (hours per day) you will likely want a good helmet or add an extra 3X plate in front of the auto helmet IMO most auto's do not go dark enough and after a day of MIGing your eyes will hurt.
On another note I REALLY like the "OMNI" lense for welding clarity and Auto darks are green only, so I use the old Tiger hood most of the time.
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