[New User Matt]

Yes, but what if for 4 AA nimh batteries you kept it between 6 - 9 volts and a charge of c/100 and less (when cloudier)?

Keep in mind this could only be for about 8 hours a day - so it would not be a continous charge.

Or if you think that would not be acceptable then what about using a shunt voltage regulator or LM317 as a current regulator - but at what current?