“Lots of solar panels which may mean lots of batteries which means potentially high levels of hydrogen gas. “
Most solar batteries are sealed.
Hydrogen gas leaks through everything and can accumulate to dangerous levels if batteries are in a confined space without ventilation.
Not entirely true. Lead acid or Nickel Iron batteries are most common for large storage because of their longevity and lower price. They can not be sealed. Lithium ion or lithium titanate batteries, yes, but they do not offgas.