Currently, the use of air-source heat pumps (ASHP) in combination with a photovoltaic (PV) installation is a very promising option for a necessary and urgent energy transformation in European countries. It is extremely important to develop solutions that will help maximize the use of energy generated from renewable energy sources. Such issues include the problem of insufficient use of generated electricity in PV on-grid microinstallations in residential buildings. This paper’s aim is to analyse the results of a one-year-round operation of a PV array grid-connected hybrid installation with ASHP for domestic hot water preparation in a residential building in Cracow, Poland, in the context of increasing self-consumption of PV energy. Models of systems are built and simulated in the Transient System Simulation software in release 18.05.0001. Simulations were carried out for different scenarios involving different building electricity consumption profiles, PV system capacity and specified runtime management of ASHP. The novelty of this study lies in the evaluation of the impact of a certain range of conditions on the energy performance of the system and in particular on increasing self-consumption. The results showed that the use of ASHP, with specified runtime management, results in an increase in monthly self-consumption values from 7% to 18%, and annual values up to 13%. Moreover, determining the appropriate size of the used PV system depending on whether it is present ASHP in the installation is crucial to increasing the value of this parameter. Overall, this study provides valuable insights into the potential benefits of PV panels and ASHP operating together, particularly on self-consumption values.

A hybrid photovoltaic-thermal collector (PV-T) with the capability to produce thermal energy and electrical energy simultaneously has attracted the attention of researchers, especially in terms of improving PV-T performance. This study analyses the work of four model installations with PV-T and other devices built in the transient systems simulation program. The novelty of this article lies in a long-term approach to the operation of PV-T panels under selected climatic conditions. Influence of the installation’s configuration on the obtained temperatures of solar cells, and, in consequence, on electric power generated by PV-T and the amount of heat produced during one year in a selected location is presented. Among others, the impact of the temperature coefficient of photovoltaic cells for long-term PV-T operation was analyzed in the paper. The results showed that the type of cell used may decrease the yearly electric energy production from PV-T even by 7%. On the other hand, intensification of the process of heat reception from PV-T using a heat pump increased this production by 6% in relation to the base model. The obtained research results indicate possible methods for improving the effectiveness of PV-T operation in a long-term aspect.

Selecting accurate climatic data is crucial for reliable simulations of Renewable Energy Systems (RESs) and the assessment of building energy performance, particularly under ongoing global climate change. Typical Meteorological Year (TMY) datasets are widely used to represent long-term average weather conditions. However, they may not fully capture regional climatic variability, recent temperature or solar radiation trends, potentially leading to substantial discrepancies in simulation outcomes. Despite the widespread use of TMY and reanalysis datasets, limited studies have systematically compared multiple contemporary meteorological databases in the context of RES simulations across Europe. This study evaluates and compares five meteorological databases—Meteonorm, TMY, TMYx, ERA5, and SARAH3—for twenty European capitals located between 38° and 56° N. A transient model developed in TRNSYS was employed to assess the performance of photovoltaic and solar collector systems with different datasets. The results reveal significant differences between datasets, with deviations reaching up to 200–300 kWh/m² in annual total horizontal radiation and 40–50% in simulated useful energy gains. PV efficiency remained relatively stable across Europe (17.7–18.7%) with very low standard deviation (<0.12%), while SC efficiency showed higher variability (25.8–28.7%). The findings demonstrate that the choice of climatic database can substantially influence energy yield predictions, technical optimization, thereby introducing significant uncertainty into the economic bankability assessment of renewable energy projects, especially in Central and Northern Europe, where climatic variability is more pronounced. The study emphasizes the need for careful database selection and periodic validation of TMY datasets in the context of evolving climatic conditions to ensure accurate, risk-aware, and future-proof energy system simulations.

In order to predict long-term changes in the temperature of the ground in which a horizontal ground heat exchanger has been installed, it is beneficial to implement simplified mathematical models of heat transfer. The possibility of using a one-dimensional equation of heat conduction while modelling heat transfer in a ground heat exchanger with horizontal pipes has been demonstrated in the work. A theoretical analysis based on the linear heat source model as well as experimental research works have been carried out. It has been concluded that the temperature profiles of the ground in which parallel pipes of the heat exchanger are placed do not significantly differ from the profiles for the heat exchanger in the form of a plate; in particular, this refers to large distances from the level in which the pipes are positioned, small distances between pipes axes and the long duration of the process. Discrepancies between the calculated temperature increases for pipe and plate exchangers varied significantly in the individual time intervals, and were approx. 20–30%. The conducted experiments have demonstrated that the temperature field around parallel pipes of the heat exchanger may be described by the linear heat source model. The compatibility of temperature maps that were determined theoretically and experimentally was satisfactory with a good degree of accuracy.