BQ24040: Using two battery charging ICs

Part Number:BQ24040

Right now we charge our device using the BQ24040, it accepts a USB cable.  It runs nicely.  Now I'm thinking about introducing solar charging on the device so the idle mode can be offset by solar power.  I have been reading the datasheet of the BQ25505, which seems to be a good option.  Now my question is, do I need both ICs?  Is there an app note showing how to have both functionality, charge by USB and supplement quiescent and sleep mode power drain by using the 25505?  

Thanks,

Darren