Estimating the performance of product integrated photovoltaic (PIPV) cells under indoor conditions for the support of design processes

To estimate the performance of PV products' cells in an indoor environment we have developed an analytical model, which calculates the efficiency and power production of various types of PV technologies as a function of distance from natural and artificial light sources. The model aims to assist designers during the energy balance calculations when creating PV-integrated products for indoor use. To validate the model, PV cells of 10 commercially available PV-powered products in the power range of 0.8mWp to 4mWp, have been measured indoors, under three types of artificial illumination (halogen, fluorescent, LED lights) and natural light. Since the model's purpose is to give a best estimation for design processes, the accuracy does not need to be high. Moreover, given the difficulty to accurately measure low irradiance (<; 20W/m
²
) so far it seems impossible to achieve highly accurate results. The measurements' analysis showed that the model can sufficiently predict the performance of PV products' cells under CFL and LED artificial lighting, as well as under mixed indoor light with a typical error around 25%. Measurements showed that under typical mixed indoor irradiance of up to 20W/m
²
, a-Si cells' efficiency ranges between 5-6W/m
²
(48%), c-Si cells' between 5-7W/m
²
(72%) and mc-Si cells' between 4-6W/m
²
(65%). Still, there are significant deviations on the model outcome for the halogen lamp, for which reason the model cannot be used in that situation yet.