America currently has a massive number number of startups in the clean energy industry and a lot of them in the fastest growing green industry that is the solar sector.However like startups in all industries a lot of them will fail,some will sell themselves to others like Heliovolt,Ausra while a few will make it really big making a fortune through IPOs for their PE investors and owners.One or two will make fortunes for those who invest early as well like First Solar.Note First Solar despite numerous ups and downs is still up more than 450% from its IPO price five years ago.It won't be the last either.So despite the strong competition in the solar industry where numerous companies and technologies are jostling in the more than $70 billion global market,one or two of the smart ones will become huge winners like Intel or Microsoft.So which are the solar startups which are showing the most promise.Four of them are currently leading the pack while a few others have got a reasonable chance of success as well though they need to prove more like Stion and Miasole.Some of the more hyped ones like Solyndra have gone on a slimming down mode and might make a comeback though it will be tough.There are some others in stealth mode which may become big also.But here is the list of the Four Best Solar Startups in the Solar Electronics,Solar Panels and Solar Thermal Sectors.