Denmark has had a successful learning curve regarding to the cost and efficiency of seasonal pit heat storage, which is used to store sunlight in summer for heating purposes in winter. Take Sunstore 3, for example, a 60,000 m³ pit heat storage system built at a cost of 38 EUR/m³ of storage capacity in the town of Dronninglund in 2014: It has now reached a storage efficiency of more than 90 %. These are some of the numbers Jan Erik Nielsen, a solar district heating specialist who works at Danish consultancy PlanEnergi, highlighted during the webinar Task 55: Towards the Integration of Large SHC Systems into District Heating and Cooling (DHC) Networks.