How the Nernst equation is applied for electrodeposition? For using the Nernst equation 

$$E = E_0 - \frac{RT}{nF}\ln\frac{[\ce{Red}]}{[\ce{Ox}]}$$

the concentrations of $\ce{Red}$ and $\ce{Ox}$ species are required. For the reaction 

$$\ce{Cu+ + e- &lt;=&gt; Cu}$$

in which the $\ce{Red}$ part leaves the solution and has no concentration in the electrolyte. How is the Nernst equation used to calculate the potential at different stages when the reaction proceeds?
For a metal electrode immersed in a solution of its own salt, the concentration of the reduced form as a solid phase remains constant ($[\ce{M^0}] = \mathrm{const}$), therefore:

$$E = E_0 + \frac{RT}{nF}\ln[\ce{Ox}]$$