Just done some calculations on the inductor:
(1)
ASSUMPTIONS
(1.1) Inductor: 40mH
(1.2) Input voltage (from solar panel): 34V
(1.3) Battery Voltage: 12V
(1.4) Switching frequency (PWM): 20KHz
(1.5) Switching mark-to-space ratio: 1:1
(2)
CALCULATIONS
(2.1) Switching period= 1/20Khz= 50uS. Thus half period = 25uS
(2.2) The voltage across the coil in the coil charge phase (MOSFET on) is 34V-12V= 22V
(2.3) Q= LI= VT. Thus maximum coil current (I) = VT/L = (22V*25uS )/40mH=
13.75 mA
(3) CONCLUSION
The inductor value is around two orders (x100) too high or the switching frequency is two orders too high.
spec
PS: Ron, please check this for gross errors