You cannot directly propel the solar sail towards the sun.

A solar "sail" is basically a mirror. The analogy of wind and sails on ships is not useful for understanding how solar sails work.

Each photon from the sun which strikes the sail is reflected. Each photon imparts a small amount of momentum. If the sail is pointed directly at the sun then you get twice the photon's momentum added to the sail. If you angle the sail, then you are sending each photon off in a direction that is not directly back towards the sun; That gives you a net force to one side. So you can control the vector of the total force of the reflecting photons, but the net direction is always more than 90 degrees from the sun. As the mirror approaches edge-on to the sun, the net force vector would approach 90 degrees from the sun and drop to zero magnitude.

(Note that the pressure from the sun's photons applies to anything. It doesn't have to be a designed sail. Orbital mechanics currently take "light pressure" into account for accurate determinations of space craft orbits.)

You can alter your orbit using a solar sail.

You can use the momentum from the solar sail to alter the orbital mechanics to go where you wish by changing the orbital eccentricity to move a part of the orbit closer to the sun, etc.

(If you want to go directly towards the sun from the earth, you don't need a force pushing you directly toward the sun. You need a force pushing against your normal orbital direction. That decreases your angular momentum about the sun, and you then fall towards the sun due to gravity.)

You cannot directly propel the solar sail towards the sun.

A solar "sail" is basically a mirror. The analogy of wind and sails on ships is not useful for understanding how solar sails work.

Each photon from the sun which strikes the sail is reflected. Each photon imparts a small amount of momentum. If the sail is pointed directly at the sun then you get twice the photon's momentum added to the sail. If you angle the sail, then you are sending each photon off in a direction that is not directly back towards the sun; That gives you a net force to one side. So you can control the vector of the total force of the reflecting photons, but the net direction is always more than 90 degrees from the sun. As the mirror approaches edge-on to the sun, the net force vector would approach 90 degrees from the sun and drop to zero magnitude.

(Note that the pressure from the sun's photons applies to anything. It doesn't have to be a designed sail. Orbital mechanics currently take "light pressure" into account for accurate determinations of space craft orbits.)

You can alter your orbit using a solar sail.

You can use the momentum from the solar sail to alter the orbital eccentricity to move a part of the orbit closer to the sun, etc.

If you want to go directly towards the sun from the earth, you don't need a force pushing you directly toward the sun. You need a force pushing against your normal orbital direction. That decreases your angular momentum about the sun, and you then fall towards the sun due to gravity.