It is harder(less efficient) than moving away from the sun using a solar sail, somewhat similar to sailing into the wind.[1] I don't have the exact numbers but

It is harder(less efficient) than moving away from the sun using a solar sail, somewhat similar to sailing into the wind.[1] I don't have the exact numbers but roughly 9.08 μN/m2 is the radiation pressure @ 1 AU and depending on sail configuration (Square/Lattice etc) we can expect a λ ~ 0.25 , with a 800m2 and 5g/m2 density sail we can get effective acceleration around 1 mm/sec2, so you can reach near the sun in few(<10) years ignoring efficiency losses due to quartering and any payload weight etc. In a real system you could speed this up a bit by using powerful lasers to improve acceleration and orbital methods like a cycler, but meaningful payload size would make it slower too. The basic metric is that escape velocity of solar system is 30km/s earth starts you at 18km/s : it is easier to add 12 than drop by 18. You can do the same things at 2/3 delta-v budget and push your payload out of the solar system than into the sun. [1] All orbits decay and eventually(10^150+ years) even the Earth will fall into sun ( or equivalent mass white drawf) so yes it is always possible