In modern agriculture today, the cultivation of agricultural products cannot be imagined without greenhouses. This paper presents an energy optimization of a solar greenhouse with a photovoltaic system (PV) and a ground-source heat pump (GSHP). The PV system generates electricity, while the GSHP is used for heating and cooling. A greenhouse is designed with an Open Studio plug-in in the Google SketchUp environment, the EnergyPlus software (8.7.1 version) was used for energy simulation, and the GenOpt software (2.0.0 version) was used for optimization of the azimuth angle and PV cell efficiency. Results for different solar greenhouse orientations and different photovoltaic module efficiency are presented in the paper. The obtained optimal azimuth angle of the solar greenhouse was −8°. With the installation of a PV array with higher module efficiency (20–24%), it is possible to achieve annual energy savings of 6.87–101.77%. Also, with the PV module efficiency of 23.94%, a concept of zero-net-energy solar greenhouses (ZNEG) is achieved at optimal azimuth and slope angle. Through the environmental analysis of different greenhouses, CO₂ emissions of PV and GSHP are calculated and compared with electricity usage. Saved CO₂ emission for a zero-net-energy greenhouse is 6626 kg CO₂/year. An economic analysis of installed renewable energy systems was carried out: with the total investment of 19,326 € for ZNEG, the payback period is 8.63 years.

The growing demand for nearly Zero-Energy Buildings (nZEBs) has positioned Building-Integrated Photovoltaics (BIPV) as a crucial solution for embedding renewable energy generation into the fabric of buildings. This paper provides a comparative overview of photovoltaic (PV) technologies suitable for BIPV—focusing on crystalline silicon (c-Si), thin-film technologies such as cadmium telluride (CdTe) and copper indium gallium selenide (CIGS), as well as emerging solutions including organic and perovskite solar cells. These technologies are evaluated based on key criteria including electrical efficiency, visual integration, mechanical flexibility, cost, durability, and applicability to various building components such as façades, roofs, and transparent surfaces. Special attention is given to how each technology meets both energy performance and architectural integration requirements essential for BIPV systems. The paper also discusses trade-offs between technical performance and aesthetic considerations, providing practical guidance for selecting appropriate PV technologies in building-integrated contexts. Several examples of existing BIPV implementations are referenced to illustrate the practical application and diversity of these technologies. The results of this study contribute to the advancement of sustainable and energy-efficient building design practices, providing support to architects, engineers, and decision-makers in achieving nZEB goals through the effective implementation of BIPV solutions.