Yes and no.
The lens has solar panels built in, so it will automatically charge the batteries, while you weld. (Just welding will recharge it, you don't need to put it in the sun)
But the batteries don't last forever, they usually last 6-12 months (there's an indicator light on the lens, that warns you before the batteries die). The lens takes 2 CR1025 batteries, and they are very cheap. A pack of 25 on Amazon is $10.