Space Battleship Yamato is a major anime movie series. The original Yamato movie in Japan eclipsed that of the local release of Star Wars. It was followed by over a dozen movie sequels.
After aliens attack in 2199, the Earth secretly builds a massive spaceship inside the ruins of the gigantic Japanese battleship Yamato which lies exposed at the former bottom of the ocean location where she was sunk in World War II. This becomes the “Space Battleship Yamato” for which the story is titled. The new ship gets a space warp drive, called the “wave motion engine”, and a new, incredibly powerful weapon at the bow called the “Wave Motion Gun”.
The actual WW2 Yamato class battleship weighed about 72,000 long tons fully loaded. It was 263 meters long and 39 meters wide. If every surface was covered with solar cells then there would be about 20,000 square meters of exposed solar cells. The solar cells on the side would be gathering power since there would be sunlight reflected from the water plus the angled light from the sun. On a sunny day there would be about 600 watts per square meter. This would generate about 12 megawatts at about high noon.
EMDrive is highly controversial. It is a potential propellantless propulsion. NASA tests of EMdrive performance seem to indicate 1.2 millinewtons per kilowatt.
There is some theories that EMdrive thrust scales with quality factor. The quality factor of a cavity is defined as the ratio of the resonance frequency to the width of the resonance curve. It relates to having low less for reflection of radiation. Very high quality factor exists with superconducting materials used for particle accelerators. Fermi Labs has material with quality factors of 60 billion. There is ongoing work to raise quality factors to 300 billion. Without being able to scale EMdrive with quality factor would require 8.3 terawatts of power to propel a 1000 ton spacecraft at 1 gravity of acceleration (9.8 meters per second per second).
An EM-Drive with a q factor of 60 billion would need 1 MWe for a one gravity acceleration of a 1000 ton spacecraft.
An EM-Drive with a q factor of 300 billion would need 200 kWe for a one gravity acceleration of a 1000 ton spacecraft.
Roger Shawyer who invented EMdrive, has the theory that EMdrive propulsion scales with quality factor but he also believes that propulsion rapidly reduces as the EMdrive moves itself. He calls this loaded Q factor. Basically once the system is moving at 0.1 meters per second what was hundreds of newtons per kilowatt of propulsion drops to a few newtons per kilowatt. This would mean that a large space battleship could use EMdrive as an antigrav or inertia countering equivalent and could move slowly with the EMDrive. The main propulsion would be from a separate propulsion.
The 12 MWe from the solar panels would just need a little bit of battery boost to lift off the EMDrive Yamato into space. As the EMdrive Yamato climbed to about 60 miles in altitude then the solar panels would generate about 21 MWe (less dissipation from the atmosphere).
A one gravity constant acceleration would go from Earth to Mars in 2 days. The last column on the right below shows round trip times from the Earth’s surface and back. It would be one gravity acceleration from the Earth and around Mars and back to Earth in 4 days. It would be 3.5 hours to get past the Moon. It would be five hours to accelerate halfway to the moon and then slowdown and land on the moon.
The hypothetical EMdrive Yamato would need non-solar power beyond Mars because the solar power would be dropping off quite a bit.