Roller blinder control using ssr - problem

I want to control blind rollers at home using ssr relays. I bought those:
Arduino ssr
It worked fine for a few says, one of ssr locked(stays on without signal).
I've read that it's because of inductive load and should add varistor on the output in parallel. THe problem is, that on diffrent forums and websites they say diffrent values. One says that for 230VAC it's voltage rating should be 275V to protect ssr, other that it should be 460.
Could someone help me with that? What should i choose?
I want to buy iTMOV

240V (my outlets have 236V in Germany) has a peak voltage at the maximum of the sine of about 340V. 275V would be a pretty stupid idea.
MOVs degrade slowly. Have a look at the datasheet how many connections it can do. AFAIR, at some point they fail SHORT, so you should add a fuse in series with both the MOV and the motor.
The probably more elegant solution is a snubber circuit. Have a look at this thread.

Is this the kind of rollershutter with one N and two L conteacts? If you use only two SSR, are you absolutely sure you will never connect both lines at the same time? Normally, people involve a NO/NC relay to make sure.

I have shared your experience with failing relays with rollershutte motors, though, so you are on the right track in general.