This work addresses the task of integrating reflectarray antennas on thin-film solar cell panels, as a means to save real estate, weight or cost of platforms, such as satellites or transportable autonomous antenna systems. Reflectarray unit cell families, having large phase range, high optical transparency and low microwave loss, are designed to preserve their efficiency in terms of solar cell and reflectarray antenna efficiency. Because there is a trade-off between the optical transparency and microwave surface conductivity of a conductor, both standard copper and transparent conductors were considered here. The results obtained at the unit cell level demonstrate, for the first time, the feasibility of integrating reflectarray on a thin-film solar cell, preserving good performance in terms of both solar cell and reflectarray efficiency. For instance, using copper, measurement at X-band demonstrates a phase range larger than 270 with an average microwave loss of 0.25 dB and average optical transparency in the visible spectrum of 85%. Using transparent conductor contributes to better average transparency (90%) at the cost of increase in microwave loss (2.45 dB).