Regent debate aside....
It will not be long before solar covered wings with minimal weight are used to recharge. As long as there is daytime, you have some power. A bright cloudless day you have a handy amount to augment the batteries and greatly increase range.
We are world leaders in solar research and have been for 30 years. We now have the ability to print a solar cell onto a plastic film. As efficient as a heavy old gen cell but will only improve. Its not much heavier than a laminating film. As development continues it will be much higher efficiency and even cheaper. Its uses basically a jet printer modified.
100 square feet as a example can provide a lot of charge and a suitable design with lighter batteries which will happen, is a exciting prospect. Long winged solar and battery aircraft have a big future. In a motor glider configuration, range at suitable speed could be very long. Then land and recharge from the sun. Add a small fuel engine to augment range when needed and we might see 4 LTS hr or less at a nice 120 knots. The small engine runs at high efficiency only when needed for boost power such as takeoff , low settings for cruise or charging. It can be wherever design and c of g dictates. A much smaller tank of say 40 litres and you could still go a long way.
The pipestrel was using only 3o HP or less with good speed. A optimised hybrid with solar could get that a lot lower.
I can imagine 120 knts cruise and 1200 nm. On good conditions lift would mean extended fuel free periods on battery/ solar power or no power.
The future has come for our dinosaurs