Performance of a multifunctional PV/T hybrid solar window

A PV/T collector have been developed and evaluated at the department of Energy and Building Design at the Technical University of Lund, LTH in Sweden. The PV/T, a “multifunctional solar window” made of PV cells laminated on solar absorbers, is placed in a window behind the glazing. The solar window is built into a single family house, Solgarden, in Alvkarleo outside Gavle in the eastern part of Sweden. To reduce the costs of the solar electricity, reflectors have been placed in the construction to focus the radiation onto the solar cells. In this way expensive solar cells can be replaced by considerably cheaper reflector material. The tiltable reflectors give the user a possibility to control the amount of radiation being transmitted into the building. The reflectors can also be used to reduce the thermal losses through the window. A model for electric and hot water production was developed. The simulation program, in Excel, can perform yearly energy simulations where different effects such as shading of the cells or the glazing effects can be included or excluded. The simulation can be run with the reflectors in an active, up right, position or with the reflectors in a passive, horizontal, position. The simulation program was calibrated against a prototype window placed in Lund in the south of Sweden and against the solar window in Solgarden. The calculation model serves as a basis for the module written for the simulation program TRNSYS. A “TRNSYS-deck” was built and calibrated for the building Solgarden. Yearly simulations of the energy balance for a house with the solar window was compared to simulations where the 16m2 solar window was replaced with an 8m2 normal window. The results show that the annual amount of auxiliary energy is lower with a developed solar window, including low-e coating on the glazing, compared to the normal window case. The developed solar window has considerable lower U-values than the existing solar window. (Less)