Development of a Simulation Model for Combined PVT and Ground Source Heat Pump Systems : A TRNSYS Model Created for Commercial Use

Abstract: The Swedish government has set a target of a 100% renewable electricity system by 2040. To reach this goal, many actions have to be undertaken. Electrification of buildings is one action to be undertaken as the residential sector accounts for a large share of greenhouse gas emissions, where the most energy efficient method is to use heat pumps. Ground Source Heat Pumps typically have the highest efficiency out of the different heat pumps. These types of heat pumps are most commonly used in single family houses, as multi-family houses often are located in highly densely areas. However, when adding hybrid PV/thermal collectors to ground source heat pump systems, studies have shown that the borehole drilling area can be reduced, which increases the potential for combined PV/thermal collectors and ground source heat pump systems in multi-family areas.  In this project, a time-efficient, flexible and user- friendly model was developed to increase the potential for designing combined PV/thermal collectors and ground source heat pump systems. The model is based on the research model by Sommerfeldt and Madani (2019), where the flexibility and time step of the model was investigated and adjusted. The finished model was verified to the model by Sommerfelt and Madani (2019). Overall, the results show that the new model gives similar results to the original model, despite all adjustments. The heaviest adjustments were made in the heat pump where the quantitative results show a mean bias error of -0.51 kWh and a total yearly difference of -5.18% for the compressor power. The corresponding values for the condenser heating rate are -1.05 kWh and -2.86%. The user is able to change boundary conditions such as location, PVT array, building size, and borehole field size. The model takes approximately 2 minutes to run for a 20 years simulation on a business grade desktop computer, which is a five-hour twenty minute reduction from the original research model and assumed to be an acceptable time range for a commercial applications.