Seed values Solving non linear equations

[roadrunner]

The reason the solver app is having trouble is that there is a discontinuity at I=0. The solution is very close to 0 so it needs a starting point very close to the solution.

If you change your second equation to:

I = (106.4*(D/2))/52000

the discontinuity is removed and the solver app has no problem finding two solutions at [[3.35617752293e−4,0.328047427054]] and at [[0,0]]

-road