Abstract: An electrodeless discharge lamp suitable for the use in solar simulators, with an emission spectrum following, as much as possible, the AM1.5G standard. According to a preferred embodiment the lamp has a quartz bulb is filled with a composition comprising an inert gas, for example N2, He, Ne, Ar, Kr, Xe or a mixture thereof, and a first and a second active components, the first active component being an antimony or bismuth halide or a mixture of antimony halides; while the second component is SnI2 a mixture of halides of: In, Sn, Ag, Bi, Cu. Preferably, the halides are bromides or iodides or chlorides due to their favorable volatilities.