Got some Maplin models form 4/5 years ago, 2 Jump Sun 600mah NiCd in them, decent size solar panel on top. Retrofitted couple with 3 green LEDs, green LED will light on microamps, one lights all year round even over Christmas for couple of hours and has done for at least 4 years.
White, green and blue all need over 3V to light so the single and double battery models use a charge pump to boost the voltage, amber and red dont need it, but are usually a sign of really naff solar lights.
Looking at the size of the actual panel gives a gues lot of them are couple of stips of ofcut buried in large amount of black gunk, look for something where the black area is actually panel.
Adam