Ok, so thats easy, I can just replace the Transistor (any thoughts as to which one I should use?)
Any npn 500mA would be OK, I use the ZTX451 or 651 1amp series.
as for the 'half on' issue, I have noticed this - depending on how dark it is will change the brightness of the LED's - thats OK with a bigger transistor though right?
The transistor should be OK.
Now Im still stuck with not getting enough juice out of the sun to fully recharge the batteries during one day - And if I do get a bigger solar panel, I have to solve the over charging issue