Im looking for 20W/h (at 5V) consuming system for running with solar panel. Is it possible with current miners? If you say it will never be profitable I say 5$ for a month is big target for me. The currency can be different than bitcoin. Im so beginner.
While there were a few USB stick miners very early in the game, rigs have rather gotten bigger than smaller since then.
According to Mining Hardware Comparison the smallest rig that is still shipping,
Antminer U3 Batch 2, needs 63W.
Its energy efficiency is only one tenth of the current best equipment though, and you'd have to invest at least $40 which you likely would never make back: In the ASIC-age, is it worth starting mining Bitcoin at home?