I can only pay for 12 hours electricity per day so I will be mining Ethereum through 12hrs only, as a rig owner do you think it's worth holding on to my mining rig or I should sell the rig and bit coins instead.
Do you have expensive electricity and can only mine at night?
I do not understand your problem, so I will give the main opinion.
The mining farm should work 24 hours a day, if you have problems with electricity, then look for other places where you can install your mining farm. If it is expensive or unprofitable, look for other opportunities to earn money.