Hi Libraman,
I have started my HID grow and so far they are working incredible. They are outperforming our 250 watt cfl grow! They are in about a week in bud and there are noticably more buds forming than the cfl's and the plants are much more bushy. The one thing i need to figure out is the reflectors. Right now the reflector i'm using concentrates most of the light to a sq ft. so i'm limited to how many plants i can grow in my cabinet. I'll be trying diferent reflectors to try to spead the light out a bit. As for running these on a solar panel you would need a pretty big one and a bank of batteries but it can be done. These draw 70 watts for the pair. Depends on how much sun you get a day.
the pictures are of my 3000K xenons and the other is a 250 watt cfl 2700K with a 100 watt biotropic 25000K cfl