Well... I'll add my .02 worth.
Right now, I am using a system that I designed to light my living room in the evenings. It is composed of a 21-watt solar panel, a 17Ah 12-volt SLA battery, a charge controller, a strip light with MR-16 bulb sockets, and three 5-watt LED lights.
I use this daily for about 4 to 5 hours in the evenings and early morning. It gets recharged during the day - even on partially overcast days.
It has been working since about April or May of this year (2007).
The LEDs are 5-watts each - for 15 watts. They are 60-degree beam width illumination, and with the three of them, I am able to light the living room, and part of the kitchen. They are rated at 150 lumens each, which is about 450 lumens total.
All in all, I am quite pleased with the performance of the system. I have a Printed Circuit board that I designed to go along with the setup, that helps with a LVD (Low Voltage Detecter) circuit and an IR (InfraRed) switch.
I would be willing to make available the P.C. Boards as a kit, or fully assembled and tested, if others are interested in this.
Regards,
James Jackson