Monitoring of indoor light conditions for photovoltaic energy harvesting

The power conversion efficiency of photovoltaic devices depends strongly on the light spectrum and light intensity. Both parameters vary significantly between different environments and locations - indoors as well as outdoors. Since placement of energy harvesting devices is governed more by the intended functionality of the system than by optimizing with respect to light conditions, the knowledge of light conditions in different environments is necessary for the design and dimensioning of photovoltaic energy converters. With this paper we want to present a simple approach to systematically measure and analyze light conditions and energy availability in different environments and to provide the basis for the development of a database of `typical' light conditions. This will help to understand the energy availability and the dimensioning and design of photovoltaic devices in energy harvesting systems.