This project demonstrates that heat pumps can reliably replace solid-fuel heating even in a demanding mountain climate, with winter temperatures below -20°C. A cascade of four Panasonic Aquarea M-Series units provides 64 kW of heating capacity, covering the entire demand of a 34-guest guesthouse while using the existing radiator system. The result is maintenance-free heating and hot water, stable comfort and lower environmental impact, supported by approximately 20 kWp of photovoltaics.