Solar panel + battery + DC load
Basically, you would need two DC-DC converters, one would charge the battery from the solar panel, and the second one would power your load from the battery. 

To be efficient, the solar-battery converter would need to implement an MPPT (Maximum Power Point Tracking) algorithm, and both converters would have to manage battery to avoid Overvoltage/Overcurrent issues. 

The exact topologies depend on your Solar panel, battery and load Voltages.