Thermal building upgrade with off-grid PV system: a Polish case

Abstract Nowadays, one of the basic requirements for thermally upgraded buildings involves limitation in CO 2 emission even by over 90%. To fulfil these criteria, it is necessary to use alternative energy sources and photovoltaics constitutes a reasonable option this. This paper addresses an analysis efficiency profitability photovoltaic system located geometric center Europe-Poland, where intensity solar irradiation not very high compared other European countries. The difference total radiation density between Poland Malta 49.2%, from based on SolarGIS base. PV Lighthouse calculator was used global power photon current examination Polish city locations highest lowest values, Finland, respectively. case study concerns building; gas boiler replaced heat pump supported off-grid system. achieve reduction 90%, install 182 cells, which generates investment costs. An entirely profitable with 70% funding Simple Pay Back Time, SPBT~7 years although Net Present Value, NPV>0; Internal Rate Return, IRR=10.6%.