Floating photovoltaic (FPV) systems have gained attention worldwide due to their potential gains in generation, land saving, and water evaporation reduction. However, experimental data from installed FPV plants operating under high irradiance and ambient temperature remains scarce. Our study presents an experimental assessment comparing FPV and ground-mounted photovoltaic (GPV) systems installed side by side in an urban area under semiarid climate. The analysis considers operating weather conditions, and focuses on photovoltaic (PV) modules' thermal and electrical behavior, as well as on the impact of FPV on the water evaporation rates. The FPV system covers 50% of the surface of a water tank; an adjacent uncovered tank is used as a reference for evaporation data. Overall, FPV and GPV modules show a similar electrical performance, with equivalence tests indicating that differences remain practically negligible at the operational scale (between -1.08% and 0.06%). FPV modules often operate at similar or slightly higher temperatures than GPV modules, consequence of low wind speed values, usually found in urban environments. In contrast, FPV modules consistently reduce water evaporation, with an average reduction of 40%, saving about 8.4 m3 during the period