Does the spacecraft use solar energy or batteries as fuel?

It depends on what kind of ship it is.

Generally, solar cells are installed on satellites or planets of solar system detectors, which mainly provide electric energy. Of course, there will be storage batteries to store excess electricity in case the electricity generated by solar cells is insufficient or needs a lot of electricity in a short time.

If it is an outer solar system detector, because it is going to fly far away from the sun, only solar cells can't provide enough power, so it is necessary to install other batteries instead of batteries, or not just batteries. Generally, nuclear fuel cells are used to generate electricity by using the energy released by the decay of radioactive elements. Pioneer 10 and 1, Voyager12, Jupiter and Saturn probes and Curiosity Mars probes use isotope nuclear batteries. American navigator 1 planetary probe, the nuclear battery on it can also be used for about 10 years.

Isotopic nuclear fuel cells can be used for a long time. Using different isotopes, the service time is as long as 1000 years.

China's Chang 'e lunar probe is also equipped with a nuclear fuel cell.