Complex sentence: Since Mercury's solar constant is 6.5 times higher than Earth's, energy for the mass driver should be easy to come by, and solar sails near Mercury would have 6.5 times the thrust they do near Earth.
Split into simpler sentences: Since Mercury's solar constant is 6.5 times higher than Earth's, energy for the mass driver should be easy to come by. This also makes the solar sails near Mercury have 6.5 times the thrust they do near Earth.