What I have done is to link up a 15w, 1.2 A solar pannel to 2 by 7.2 AH batteries. This I run trough a controller that charges the batteries during the day and then runs the lights at night. I also use the system to power my hydroponic system.
The panel is 26v so I had to run it though a voltage regulator to drop it to 14v. then the day night system I got from another site(check it out here). it is very simple and works well, I did try to use a few commercial ones but they did not handle the load. at night the relay switches off and I get direct feed from the batteries to the LED's. I have split the the LED's into 2 systems. One is the 12v wich are the mini flood lights and then 3.3 volts that drive the night lights in our house and the lights all under the roof.
So far day 3 and the system is stable ... using about 30% of the total bat power over 10 night hours .... let see how the system handles.
oh forgot to add so far I am running 86 5mm ultra bright LED's rated at 3.3V, 10MA
Will keep you in touch on this one.