python - How do I sudo a command in a script without being asked for a password?

I want to turn my system on automatically every day. So I use the below code in my Python script, but sudo asks me for a password every time:

os.system('sudo sh -c "echo date \'+%s\' -d \'+ \
       24 hours\' > /sys/class/rtc/rtc0/wakealarm"')

How can I run this script without sudo asking for the password every time?