Cost. Always cost. Solar panels have a ~20 year return on investment vs. grid ‘leccy as it stands. Storage of H is decidedly non trivial as everything has to be machined to seal to much finer tolerances AND it’s explosive from the 35% H: air saturation point onwards. The other issue is that burning H in a car points to an engine other than a piston type, most likely a turbine or fuel cell. Now, fuel cells are an order of magnitude more expensive than IC piston engines so right now, they’re out. Turbines on the other hand are a power of ten more expensive (7-8x per unit power). The problem with them is fuel efficiency. They’re horrendous. They work best when being run at continuous high power and just being left there for as long as possible. Cycling of the power only makes the fuel burn worse. So, the best way to take advantage of a turbine in a car is to link it to a generator and that to some form of electric drivetrain. Yes that’s right, a hybrid. Hybrids in this case use a battery to act as a grid, soak up the power generated and provide it back to the drivetrain. Exactly what a fuel cell would require. So, the argument becomes one of cost. Internal combustion piston engines (with already developed and paid for infrastructure) at known cost versus massive design and cost problems to achieve the same performance. With the enormous infrastructure problems behind it all. That’s the problem behind the debate.