This driver:
What U1 have you used?
What type of transistors are Q2 and Q3?
(1) One of the first things I notice is that Q1 gate stopper R2 (10R) is shown in the wrong place. R2 should connect physically directly to the gate of the NMOSFET to stop Q1 from oscillating. So R3 top should connect to the left of R2.
(3) The other thing is that your layout may be causing the NMOSFET to oscillate. Can you post a picture of your layout.
(4) There is no decoupling capacitors shown. You need a 22uF ceramic capacitor connected physically from Q2 collector to Q3 collector.
(5) Another 22uF ceramic capacitor is required physically between the drain of the NMOSFET Q1 and OV (shown as ground on the driver schematic).
(6) Note if you do not have any 22uF ceramic capacitors, a 100nF ceramic capacitor in parallel with a 22uF aluminum electrolytic capacitor will do.
(7) The driver looks very slow, due to the high value of R6 (10K). This could also be causing problems.
(8) In general, I hate to say this, but that is not the best driver circuit I have seen.
(9) You might also like to try putting a 2m2 F (2200 uf) capacitor or larger across the output of the solar panel close to the NMOSFET unless the solar panel already has a large capacitor across it.
spec