The combined connection produces a total of 15 amperes (5 + 5 + 5) at 12 volts DC, giving combined wattage of 180 watts (volts x amps), compared to the 60 watts of just one single panel. A modern 2026 solar panel has three voltage numbers on its datasheet, and they all matter for different reasons. In this example, the series string will have no losses. This way, you can readily tell the optimal configuration for your solar power system. Losses come from inverter efficiency, wiring, temperature, and dirt.