This review study, framed in the Work group 4 “Photovoltaic in built environment” within the COST Action PEARL PV, CA16235, aims to examine applications of integrated and applied photovoltaic technologies on ten landmark buildings characterised by distinctive geometries, highlighting the aesthetics of their architecture and quality of PV integration based on a proposed set of seven criteria. The selected building samples cover a large design diversity related to the quality of PV systems integration into building envelope that could serve as a basis for general guidelines of best architectural and technological practice. After introducing the problem and defining the research methodology, an analysis of ten landmark buildings is presented, as representative models of aesthetics of their architecture, photovoltaic integration and implementation and energy performance. The study concludes with the main characteristics of photovoltaic integration on landmark buildings. The paper is intended to support both engineers and architects in comprehending the convergent development of contemporary architecture and photovoltaic technology, as well as the need for a closer collaboration, sometimes resulting in architectural masterworks that promote the diffusion of photovoltaics to the public.

The energy output of solar-thermal systems using flat plate collectors can be improved by tracking. Tracking is well known as a path for increasing the amount of solar radiation received by the collector; additionally the paper proposes a new concept that considers the inverse tracking as a viable option for protecting the collectors against overheating. An analysis of the thermal energy output and conversion efficiency is done considering forward tracking in three different days with different radiation profile (cloudy, sunny and mixed days), followed by an analysis of the inverse tracking concept. The in-field data show that there is a limiting angle below which inverse tracking is not effective and this value is estimated at 40° as compared with the optimal orientation. A logical scheme is proposed based on four different programs for forward tracking, inverse tracking, maximum inverse tracking or fixing the collector; this decisional scheme covers a broad range of functional situations having as central concept the production of thermal energy only when needed, for satisfying the demand, decreasing the energy consumption for forced circulation and supporting the systems reliability and safety

A total of five different types of photovoltaic (PV) modules were comparatively analyzed in terms of electrical output, efficiency, and relative efficiency losses, based on infield data collected in a temperate mountain climate, to outline the influence of the high relative environmental humidity on the PV conversion efficiency during time intervals with clear sky and low amounts of incident solar irradiance. The mono- and poly-crystalline silicon, cadmium telluride (CdTe), copper indium selenium (CIS), and copper indium gallium selenide (CIGS) modules mounted on a fixed tilted, South-oriented platform were individually monitored or in groups of modules using power optimizers. The electrical energy production, the PV conversion efficiency, and the relative efficiency losses were correlated with the weather data, and the analysis discusses the lower electrical energy output during periods with high relative air humidity. The analysis indicates that in a temperate climate, during days with high humidity intervals similar to the ones discussed in the paper, crystalline silicon modules have the lowest efficiency losses, followed by CdTe, CIGS, and CIS modules. The results can be useful for PV system designers, installers, and end-users of PV systems for a better system design and for a more accurate prediction of the daily energy production.

This article presents a mathematical model for estimating the direction of the maximal global solar irradiance (MGSI) based on actual values of direct/beam and diffuse irradiance, model that can be used to determine a correct value of the global collecting efficiency of solar tracking systems. Using this model, the collecting efficiency can be improved by tracking the solar conversion surface to minimize its incidence angle with the maximal global irradiance instead of the beam irradiance. The analysis of the numerical results obtained using in-field data-based simulations showed a significant improvement of the real collecting efficiency, especially during cloudy days when the diffuse irradiance is preponderant.

One key component of the energy demand in the built environment is the thermal energy required for domestic hot water preparation. Currently, fossil fuels are mostly used to meet the thermal energy demand in the built environment, lately, solar thermal systems have been increasingly implemented, mainly for domestic hot water preparation, enhancing the building's sustainability. A case study is presented in the paper for a solar thermal system with six flat plateand three evacuated tube solar thermal collectors installed on the rooftop of the Renewable Energy Systems and Recycling Research Centre, in the Colina Campus of the Transilvania University of Brasov, Romania. In 2017, this system provided 17,412 kWh of thermal energy to prepare domestic hot water for a Solar House and for the Sports Hall locker rooms. Evacuated tube solar thermal collectors showed better specific thermal output than flat plate ones.