Comparative techno-economic assessment of solar district heating architectures based on combined solar thermal collectors, heat pumps, PVs and batteries

• Unified techno-economic assessment framework solar district heating systems. • Integration of solar thermal/thermal energy storage and PV/battery/heat pumps. • Solar fraction dominated by solar collectors area and thermal energy storage size. • Seasonal thermal energy storage needed for high solar fractions in Munich/Copenhagen. • Optimal sizing of solar district heating highly sensitive to electricity prices. The present work investigates how the relative sizing of thermal (solar collectors, thermal energy storage – TES tank) vs electrical (PVs, heat pumps, batteries) conversion pathways of a generalized solar district heating (SDH) system affects its (a) environmental (solar fraction) and (b) economic (levelized cost of heating – LCOH ) performance. For this purpose, a novel, unified techno-economic assessment framework is applied for a 1,000 persons community in Athens, Munich and Copenhagen for maximum collectors/PV areas of 10,000 m 2 . For SDH without PVs/batteries, 100 % solar fractions are achieved in Athens by diurnal storage and collector areas above 6,000 m 2 . However, maximum collector areas and seasonal storage is necessary in Munich /Copenhagen to achieve maximum solar fractions (about 50–60 %). Because of higher electricity prices in Athens, cost-optimal systems do not include heat pumps. In Munich/Copenhagen, heat pumps are cost-effective for lower solar fractions and lower electricity prices. The addition of PV/batteries results in small increase in the solar fraction, which is nevertheless mainly affected by the collectors area. With electricity exports, cost-optimal systems include maximum PV areas without batteries exporting electricity and minimum required collector areas/tanks for targeting the desired solar fraction. In Munich/Copenhagen, small-sized heat pumps are cost-effective for lower electricity prices. Whereas batteries are not cost-effective, they are necessary for higher solar fractions in these two cities. Without electricity exports, adding PV/batteries results in higher LCOH , thus thermal conversion is cost-optimal. Overall, electricity prices and PV renumeration schemes significantly influence optimal relative sizing of thermal vs electrical pathways of SDH systems.