Solar eclipses on Neptune occur when substantial natural satellites of Neptune pass in front of the Sun as seen from the planet.
For bodies which appear smaller in angular diameter than the Sun, the proper term would be a transit and bodies which are larger than the apparent size of the Sun, the proper term would be an occultation.
All of Neptune's inner moons and Triton can eclipse the Sun as seen from Neptune.
All other satellites of Neptune are too small and/or too distant to produce an umbra.