i think it will be profitable because you don't need to pay for monthly electricity bill because of solar panel..
Where do you think the solar panels come from, the solar panel fairy drops them off under you pillow for free one night?
Solar power has a HUGE initial cost and you have to amortize that cost over your expected life use of the system. You have to ROI the solar array
and your miner hardwares.
start right now before halving ends because it will more profitable if you sell your bitcoin you already mined after halving..
That's speculation, no one knows what will happen at the halving. Who knows, price could just as easily to the other way and everything be worth less.
Indeed. ROI on PV these days is 5-10 years depending on where you live, prices and so forth.
Also don't forget to factor in costs for transformer to convert PV output to whatever voltage your mining hardware uses. (I just checked and AntMiners use DC which is nice!).
I recommend against getting batteries to mine at night -- DC backup is still pretty expensive. Though of course with the halving coming, you'll need to run the numbers...