Charge LiPo battery with solar panel
I see no reason this wouldn't work. Of course, you can only charge a single cell at a time with the Max1555, but you should be able to connect the solar panel directly to the chip as the Max1555 accepts input voltage from 3.7 - 7 V. As long as the output voltage from your solar panel is going to stay in that range I think you'll be fine. Just be aware, 100 mA could take a long time to charge your battery, depending on its capacity.