Solar powered garden lights bought from the shop don't shine all night , but with this design it will shine for 2 or even 3 nights on one full day time charge. Is a combination of a joule thief circuit coupled to a day/night sensor circuit.
I took 4 old solar cells and combined them to produce 2 volts and about 80 milli amp.
this charges 2 AA batteries in parallel ( NiCd 600MA). The joule thief circuit uses much less current than a convention strait hookup to the led's so it lasts much longer.