Methods for arc detection in a system including one or more photovoltaic generators, one or more photovoltaic power devices and a system power device and/or a load connectible to the photovoltaic generators and/or the photovoltaic power devices. The methods measure voltage, voltage noise and/or power delivered to the load or system power device. The methods may compare one or more measurements, an aggregation of measurements and/or values estimated from the measurements to one or more thresholds, and upon a comparison indicating a potential arcing condition, an alarm condition may be set. Embodiments include an arrangement of photovoltaic generators and photovoltaic power devices for reduced-impedance voltage loops which may enhance arc-detection capabilities.