This work by my colleague Mikel Lumbreras and myself just went online today. It was actually presented in the IBPSA conference Building Simulation 2019 in Rome last September.
This work performed energy and economic assessments over the integration of façade integrated Solar Thermal systems and low temperature District Heating networks. Compared to isolated solar systems, as much as 50% additional heat was produced over a full year period, with profitable economic metrics.
you can of course access the full paper in the following URL: http://www.ibpsa.org/proceedings/BS2019/BS2019_210282.pdf
Full conference proceedings are available in the following URL:
http://www.ibpsa.org/building-simulation-2019