R
Radiance
Instantaneous solar radiation leaving or arriving at a point on a surface; it is measured by kW/mē. The radiance taken at the equator at midday and in optimal weather conditions is equal to 1 kW/mē.
Rectifier
A device that converts AC to DC, as in a battery charger or converter. See 'inverter.'
Reflected irradiance
See: Albedo.
Remote systems
Systems off of the utility grid.
Renewable energy
Flows of energy that are regenerative or virtually inexhaustible. Most commonly includes solar (electric and thermal), biomass, geothermal, wind, tidal, wave, and hydro power sources.
Resistance
The property of a conductor which opposes the flow of an electric current resulting in the generation of heat in the conducting material. The measure of the resistance of a given conductor is the electromotive force needed for a unit current flow. The unit of resistance is ohms.
Ribbon
Bus bar of tinned copper connecting cells electrically.
