The ratio of actual power being used in a circuit, expressed in watts or kilowatts, to the power that is apparently being drawn from a power source, expressed in volt-amperes or kilovolt-amperes.
_:
P-Type Semiconductor
A semiconductor in which holes carry the current; produced by doping an intrinsic semiconductor with an electron acceptor impurity (e.g., boron in silicon).
_:
Pulse-width-modulated (PWM)
A function of many of the newer charge controllers and battery chargers which instead of applying a steady DC voltage to the battery, sends out short pulses. The width of the pulses varies with the battery state of charge.
_:
Pyranometer
An instrument used for measuring global solar irradiance.
_:
Pyrheliometer
An instrument used for measuring direct beam solar irradiance. Uses an aperture of 5.7° to transcribe the solar disc.
_:
Self-Discharge
The rate at which a battery, without a load, will lose its charge.
_:
Semiconductor
Any material that has a limited capacity for conducting an electric current. Certain semiconductors, including silicon, gallium arsenide, copper indium diselenide, and cadmium telluride, are uniquely suited to the photovoltaic conversion process.
_:
Series Connection
A way of joining photovoltaic cells by connecting positive leads to negative leads; such a configuration increases the voltage.
_:
Silicon (Si)
A semi-metallic chemical element that makes an excellent semiconductor material for photovoltaic devices. It crystallizes in face-centered cubic lattice like a diamond. It's commonly found in sand and quartz (as the oxide). The most common semiconductor material used to make photovoltaic devices.
