Attaching temperature sensors to solar cells
Is there another way to do it?


Yeah, you could just tape it to the solar module. If you need thermal conductivity you could apply thermal paste around the thermistor. If you have air around the thermistor, the more thermal resistivity you will have and the longer the thermistor will take to equalize to the solar module. Kapton tape is great becasue it is high temperature.

The idea is you'd want the thermal resistivity between the module to be low enough to equalize to the modules temperature. Since the module itself is proabably going to have a much larger time constant than the thermistor, the thermistor will proabably equalize even if you had a small point of contact. To be sure you could put a small dab of thermal grease on it and tape it on. Taping the thermistor wire to the module will also help equalize the temeprature. 

You could use a thermal epoxy also, but you would be dealing with epoxy which isn't that fun. 

As far as thermistor type, get one that has the temperature range and accuracy you need.