user14248: What i am asking is a relative threshold on the minimum Hash rate needed to mine solo, taking into account todays difficulty,could it be an ASIC of 1TH/s or 5TH/s so as to compare with pool mining

user12034: There is no minimum power needed to mine solo. You should note, however, that if you mine solo, your rewards will be much more inconsistent than if you mine in a pool. This is the major reason why pooled mining exists.
With 5 TH/s at the current difficulty, the average time for you to find a block is 38 days; with 1 TH/s, 189 days. But this is a random process that would average to 38 (or 189) days, and that time period is only likely to grow larger as time goes on. You have a real chance, then, of never getting any reward for your work (the reverse is also true, of course: you have a chance of finding more than expected...but I wouldn't stake thousands of dollars on it). Personally, I'd want an expected period of no more than 10 days/block (~20 TH/s currently) to consider solo mining a good option.
Also of note: your intuition of how any random process will work out is very probably very wrong. I'd go for mining in a pool so that I don't have to deal with any large amount of randomness in this process.

14248: <p>What i am asking is a relative threshold on the minimum Hash rate needed to mine solo, taking into account todays difficulty,could it be an ASIC of 1TH/s or 5TH/s so as to compare with pool mining</p>
 12034: <p>There is no minimum power needed to mine solo. You should note, however, that if you mine solo, your rewards will be much more inconsistent than if you mine in a pool. This is the major reason why pooled mining exists.</p>

<p>With 5 TH/s at the current difficulty, the average time for you to find a block <a href="http://www.bitcoinx.com/profit/" rel="nofollow">is 38 days</a>; with 1 TH/s, 189 days. But this is a random process that would average to 38 (or 189) days, and that time period is only likely to grow larger as time goes on. You have a real chance, then, of never getting any reward for your work (the reverse is also true, of course: you have a chance of finding more than expected...but I wouldn't stake thousands of dollars on it). Personally, I'd want an expected period of no more than 10 days/block (~20 TH/s currently) to consider solo mining a good option.</p>

<p>Also of note: your intuition of how any <a href="https://en.wikipedia.org/wiki/Randomness" rel="nofollow">random</a> process will work out is very probably very wrong. I'd go for mining in a pool so that I don't have to deal with any large amount of randomness in this process.</p>
