What is the main effect of connecting photovoltaic (PV) modules in parallel?

Connecting photovoltaic (PV) modules in parallel primarily leads to an increase in current while maintaining the same voltage output. Each module produces a certain voltage level based on its design and characteristics. When connected in parallel, each additional module contributes its current to the total output of the system.

For instance, if you have several PV modules, each generating 5 amps at 20 volts, connecting them in parallel would result in a total current of 15 amps at 20 volts if three modules are used. This higher current increases the system's ability to deliver power, as power is the product of voltage and current (P = V x I).

The other choices do not accurately reflect the effects of connecting modules in parallel. Voltage increases would occur when connecting in series, and power output does not reduce simply through parallel connection – it typically remains steady or increases. Efficiency also does not inherently decrease due to the configuration of the modules being parallel. Thus, the correct answer is that connecting PV modules in parallel results in increased current.