The Digisolar project aims to significantly advance the decarbonisation of industrial processes of the Komotini Paper Mill, through the optimisation, demonstration and validation of an integrated Solar Energy Heat Generation System (SEHUS). This innovative system combines solar thermal and photovoltaic energy, a high temperature heat pump (HTHP), thermal energy storage in a water tank (TES) and waste heat recovery (WHR) from the biomass boiler flue gases. Initially, the thermal solar panels (ST) that will be installed in the southern plot of​​ the Paper Mill factory will produce pressurized water at temperatures of 120-160°C, which will be stored in a special graded TES tank. The temperature will then be upgraded by the HTHPs heat pump, which will be powered by electricity provided by the photovoltaic panels (PV) which will be placed in the area south of the thermal panel park, within the company’s plot.

At the Komotini facility, the ST power is 400kW and the heat storage tank is 15m3. The PV panel power is 100kW and the heat pump power is 378kW. This decision was made to enhance the flexibility of the system and enable night-time operation of the HTHP during the summer, thanks to the appropriately dimensioned TES tank. An air-to-water heat exchanger was finally chosen, which will preheat the boiler feed water up to 180°C ensuring more stable performance. The boiler efficiency will also be improved by installing a waste heat recovery (WHR) unit from the flue gas exhaust. This will lead to increased energy efficiency, increased supply temperatures and reduced CO₂ emissions. The electricity required by the heat pump will be provided by the 100kW PV Park and the grid.