I have applied them here many times.
we have 2 desklamps that run 9-10 watts Max, that outshine the halogen 20w things they replaced.
they make believe that they are as efficient as florescent, and basically they do use phosphors like florescent lights do. and they make believe that they are 10x more efficent than a light bulb, but reality use of them says they are 2x more efficient.
the real efficency is when used as a point source lighting. aiming the light in the direction it is actually needed, instead of blowing it all out in some shaded lamp or blowing it all over the walls.
they originally claimed a 100,000 hour life span, then they changed to a 50,000Hr stat, which is more realistic. see because the materials that make an led, DO last for a LONG time, look at all the small indicators that have burned non stop for 10-20 YEARS, but phosphors do not last that long when triggered. so how long in REALITY they will last is really unknown.
we have burned them here for almost 2 YEARS non-stop, and the ouput is similar to a new one.
in Flashlights, the batteries in the flashlights made with them last at LEAST 5X as long, and the light out of them is much better for a flashlight, when used with the manufactures optics, its a very nice blend.
i will NEVER have a flashlight again with them stupid normal bulbs, if you dont have a primadonna led flashlight your missing out.
they do get hot, but you can totally control the output, and sync them to something, like the lamp or a aluminum strip to use as a light bar.
like at 3V they output enough light for my computer stuff (12x1w) using about 2-3w of total power.
they can be Banked, like solor cells, so you can run them off of 10.4v or 14.4 and similar.
you solor people would like the one aspect of what i did with them in the automobiles, by setting them up in 14.4 banks when the car is charging they are very bright, but when your battery is Low the current use goes way down.
i put them in the automobiles because people would sometimes leave the door open, or light on, and it would kill the battery, now the dome light (set) can be on for 2 WEEKS, and i can still start the car. not even going to happen with the usual dome lights in cars.
they are very voltage critical.
at 3.6v they will use 350-500ma
at 3.0v they will use about 50ma
so the power (voltage or current) should be regulated.
BUT, and this is a neet trick, if you do it right, instead of loosing All light as your batteries go lower, the light just dims more.
i would think that for solar lighting they would be IDEAL if you set it up like i did, with less circuit and regulation garbage, and allow it to do what it does when there is less power available.
here are some pics of the desklamp thing
http://www.boomspeed.com/nitram/DSC00593.JPG
http://www.boomspeed.com/nitram/DSC00592.JPG
http://www.boomspeed.com/nitram/DSC00594.JPG
http://www.boomspeed.com/nitram/DSC00595.JPG
this lamp is "special" :-) it has dimmers and a sattalight for lighting other areas.