Performance comparison of building-integrated combined photovoltaic thermal solar collectors (BiPVT) with other building-integrated solar technologies

•A new TRNSYS type is written to model unglazed BiPVT with a direct flow absorber.•Simulations for multi-family buildings under weather conditions in Denmark and Spain.•Economics of BiPVT systems of different size is compared to traditional alternatives.•Comparison for different heat and electricity prices and investment cost assumptions.•In cold climates, BiPVT systems can compete with alternatives only in special cases.•In warmer climates, a similar BiPVT system performs better.