As stated before, it comes down to how many time you want to invest and how expensive your power is.
I started of by buying a kw/h measuring gadget and i let my SP20E run for a month, after that i calculated if i made any profit at all.
In my case i came out even, because the electricity is around 17 cents per KW. Still i find the exchange from money to electricity to BTC to  money again quite fun and i like to fumble around electronics. So that's a huge plus for me.
And if you are here for profit, having a S7 Antminer would be a huge bonus.
I hope that's an ok answer for you!

i am new at the whole thing, just reading now.

is he solo mining?

I've seen it, i think i'm getting the hand of this. Awesome! 

thank you for your answer, i've switched back to kano.is and i'll leave it there for 2 days. i hope it gets better. thx!!

i changed to slushpool, after a 12 hour overnight shift and no income.
i have worked on the #409592   omtest_2101826- block and i received nothing for it. that's why i'm asking, whether i'm earning something on confirmations not wasting power. tnx

Hi guys i'm quite new to this. I have about 1.5Th/s on a SP20 throughout the day. I started mining on kano couple of days ago and so far so good. My question is, when a block has been found, it then goes through a confirmation process. if my miner is working on kano whilst the blocks are getting confirmed, is it earning money? i've been searching for days on the net and can seem to find an answer. thank you very much!