Hi All,
if you want to get the maximum power out of your solar panels at different sunshine
levels, you need to get a MPPT Maximum Power Point Tracking solar controler.
Here is a very interesting video Playlist series about this.
http://www.youtube.com/watch?v=MSz4-cr3EJw&feature=share&list=PLjzGSu1yGFjWv4KeN-7TSYeQIcicM9Ghl (http://www.youtube.com/watch?v=MSz4-cr3EJw&feature=share&list=PLjzGSu1yGFjWv4KeN-7TSYeQIcicM9Ghl)
and here is a good basic method article about it:
http://en.wikipedia.org/wiki/Maximum_power_point_tracking
Regards, Stefan.