These scenarios, both large and small, are covered currently by fossil fuels, and are not answered by permanent grid solutions like HVDC.
The generation price of solar energy is ~$0.02/kwh. Even with 33% overall efficiency hydrogen could be very competitive at $0.06/kwh electricity. , But overall efficiency is a red-herring. The important thing is COST. With solar, the cost of energy itself is the smallest part - providing it at the desired time and place are the more expensive parts.
Fossil fuels are very inefficient, yet for hundreds of years they have been a cheap option (and thus widespread). The same argument applies to hydrogen - if it's cheaper, in terms of money, time and pollution, efficiency doesn't matter a bit.