Traditional p-i-n junction solar cells imbedded with quantum dots are attractive to achieve chromatic light absorption enhancement. In this paper, multi-layer stacked GaAs and In0.1Ga0.9As quantum dots grown by the droplet epitaxy technique are sandwiched between Al0.4Ga0.6As layers for solar energy harvesting. The performance of GaAs and InGaAs quantum dot solar cells is compared using structural, optical, and electrical measurements. The two-step photon absorption process is studied via adding external infrared pumping sources in quantum efficiency measurements at room temperature. This work demonstrates that strain-free nanostructures by droplet epitaxy are promising for photovoltaic application.