A lot will depend on your circuit properties and also what are you using to switch the solinoids.
A small snuber circuit ( capacitor resistor or dedicated component ) can remove surious induction currents. Good quolity solinoids are also a must
Your bigest problem is generating spikes rather than induction currents.
Be carfull because you can generat a large magnetic field that can cause humming and buzzing.
Barrybear