Availability Of Solar Radiation Research Articles

Enhancing the Strategies of Climate Responsive Architecture, The Study of Solar Accessibility for Buildings Standing on Sloped Sites

One of the fundamental parameters for low energy architecture strategies implementations is to allow solar sun penetration into buildings, which can contribute to free heating in buildings and reduce energy consumption during cold season; through many design strategies that could be applied to buildings.
 
 This is not easily achieved until a complete analysis of solar accessibility is done, which in turn enables us to decide whether such strategies are applicable or not.
 
 Amman city is a case where such analysis is a must due to the problems of fuel scarcity and high fuel costs as well. In addition, the topographical nature of Amman city is not plain; rather it is almost mountainous, which makes it important to ensure solar accessibility on slope sites.
 
 Much of modern apartments in Amman were built on sloped sites.
 
 Method of research will depend on selected cases for solar radiation quantification for a number of cases including mainly modern residential buildings built on slope sites; this method will depend mainly on graphical analysis for solar penetration (INSOLATION) and theoretical calculations for the different cases.
 
 Calculations of solar radiation were based on measured global irradiation, they were calculated for the under heated period for Amman; then a strategy were built to derive new set back values.
 
 Recommendations will be as a set of rule of the thumb for direct application for the practicing architect, and they are reflected as new setback values between buildings. It will be the first step towards a complete set of regulations to ensure solar accessibility to buildings constructed on slope sites in Amman city and for other regions of similar slopes, looking for the target of maximizing solar radiation availability for minimizing fossil fuel consumption as an introduction to the study of sustainable buildings in Jordan.

An Optical Algorithm to Estimate Downwelling Diffuse Attenuation Coefficient in the Red Sea

An optical algorithm is developed for the retrieval of the downwelling diffuse attenuation coefficient $K_{d}$ (490) in the Red Sea using a comprehensive hydrolight simulated data set ( $N = 5000$ ). We found a robust relationship between the $K_{d}$ (490) and the ratio of remote sensing reflectance $R_{\text {rs}}$ (443)/ $R_{\text {rs}}$ (555), with an excellent determination coefficient ( $R^{2} = 0.999$ ) and a low root-mean-square error (RMSE = 0.00033). The performance of the developed algorithm is evaluated with in situ data collected in the Red Sea by comparing obatined model output with existing empirical (NASA, Morel et al. , Zhang and Fell, Tiwari and Shanmugam) and semianalytical (Lee et al. ) algorithms. On the used in situ data from the Red Sea, the new algorithm shows good retrievals of $K_{d}$ (490) with a low bias, and a low RMSE compared to that of the existing algorithms. For satellite application, we applied our algorithm to selected MODIS–Aqua images acquired over the Red Sea, which captured spatial features of phytoplankton blooms and physical processes (e.g., cyclonic and anticyclonic circulations) in the Red Sea. The new algorithm has the potential to improve our understanding of water transparency and photosynthetic processes that rely on the availability of solar radiation.

Model for Estimation of Global Horizontal Irradiance in the Presence of Dust, Fog, and Clouds

The poor spatial resolution of available ground data provides an opportunity to estimate solar irradiation from computational models based on the satellite data. The developed model employs various spectral bands of the satellite data and focuses on distinguish weather signatures, such as: dust, aerosols, fog, and clouds. These parameters affect the solar radiation availability all over the world. However, for a tropical country like India, which is potentially rich in solar energy resources, the study of these parameters is of crucial importance. A modified version of the HELIOSAT model is developed and an all-day index based on various bands of satellite data is introduced. Results are validated against the ground data recorded at various stations of the Indian Meterological Department as well as with the Meteosat East data.

Agroforestry systems and their effects on the dynamics of solar radiation and soybean yield

Agroforestry systems have been highlighted in the agricultural environment as an alternative form of sustainable production to meet the growing demand for food and energy with less environmental impact. Thus, the aim of this study was to evaluate the effect of different forest species on the dynamics of solar radiation and the productive response of soybean grown in agroforestry systems. Two field experiments were carried out in the city of Frederico Westphalen - Rio Grande do Sul, Brazil. In order to reach the aim of this study, the solar radiation transmissivity and the productive performance of soybean were evaluated. Productivity followed the same tendency as solar radiation transmissivity; in an agricultural year, the species with the higher incidence of solar radiation to the understory presented the best yield. The forest species Schizolobium parayba, Peltophorum dubium and Parapiptadenia rigida were used as they present the potential to compose the agroforestry systems; their canopy structure and leaf architecture provide greater availability of solar radiation in the subforest. The interception of solar radiation by the forest component of more than 50% significantly reduces soybean yield in agroforestry systems, requiring silvicultural practices that promote the availability of solar radiation in the understory.

Prediction of Solar Radiation Intensity using Extreme Learning Machine

The generated energy capacity at a solar power plant depends on the availability of solar radiation. In some regions, solar radiation is not always available throughout the day, or even week, depending on the weather and climate in the area. To be able to produce energy optimally throughout the year, the availability of solar radiation needs to be predicted based on the weather and climate behavior data. Many methods have been so far used to predict the availability of solar radiation, either by mathematical approach, statistical probability, or even artificial intelligence-based methods. This paper describes a method of predicting the availability of solar radiation using the Extreme Learning Machine (ELM) method. It is based on the artificial intelligence methods and known to have a good prediction accuracy. To measure the performance of the ELM method, a conventional forecasting method using the Multiple Linear Regression (MLR) method has been used as a comparison. The implementation of both the ELM and MLR methods has been tested using the solar radiation data of the Basel City, Switzerland, which are available to public. Five years of data have been divided into training data and testing data for 6 case-studies considered. Root Mean Square Error (RMSE) and Mean Absolute Error (MAE) have been used as the parameters to measure the prediction results based on the actual data analysis. The results show that the obtained average values of RMSE and MAE by using the ELM method respectively are 122.45 W/m<sup>2</sup> and 84.04 W/m<sup>2</sup>, while using the MLR method they are 141.18 W/m<sup>2</sup> and 104.87 W/m<sup>2</sup> respectively. It means that the ELM method proved to perform better than the MLR method, giving 15.29% better value of RMSE parameter and 24.79% better value of MAE parameter.

Solar radiation on south‐facing inclined surfaces under different climatic zones in India

In this work, solar radiation availability has been estimated for south‐facing inclined surfaces in India. Five different climatic zones prescribed by Energy Conservation Building Code (ECBC) for India have been considered. A comparison of optimum tilt angles and corresponding incident solar radiation for representative locations under different climatic zones, that is, Srinagar (cold), Delhi (composite), Jodhpur (hot and dry), Mumbai (warm and humid), and Bangalore (Temperate) has been established. Gains in the availability of incident solar radiation in comparison with a horizontal surface observed for Jodhpur and Bangalore were found to be maximum (15.77%) and minimum (7.57%), respectively, on monthly optimum tilt angle. A loss of 5.74% for cold climate, 7.49% for composite climate, 6.16% for hot and dry climate, 4.30% for warm and humid climate, and 4.39% for temperate climate were estimated with surface tilted at annual optimum tilt in comparison with a surface at monthly optimum tilt angle. A linear relationship was observed between annual optimum tilt angles and locations latitude as βopt(annual) = 0.671 ϕ + 9.087 with R2 = 0.9984. It was concluded that climatic conditions can considerably affect the availability of incident solar radiation under different climatic zones. ‘ 2018 American Institute of Chemical Engineers Environ Prog, 38:e13050, 2019

Simulation of thermal performance of solar greenhouse in north-west of Iran: An experimental validation

Application of solar energy in greenhouse heating during the cold months could be of great importance. In this study, six shapes of greenhouses including: uneven span, even span, single span, vinery, quonset and arch type were compared from solar radiation availability point of view. A dynamic model was developed to predict all the internal greenhouse temperatures including inside air, soil surface and north wall temperatures for the selected greenhouse. In this model the radiation component of the heat transfer was used along with the other heat transfer modes. Experimental validation to obtain required parameters was conducted in single span greenhouse (in east-west orientation). The results showed that, as compared to other shapes, the single span shape greenhouse oriented in east-west orientation received about 8% more solar radiation during all the months in a year. It was also determined that using brick wall at north side of the greenhouse can reduce radiation energy loss in this type of greenhouse. The average value of the cover transmittance was estimated to be 0.76 during the period of the experiment. A good agreement was obtained comparing measured and predicted values.

Prospect of Floor Heating System in Residential Buildings in Kathmandu Using Compound Parabolic Concentrator (CPC)

Underfloor heating system is more suitable for space heating because of its unique temperature gradient profile. If solar radiation can be utilized for heating of water in radiant floor heating system, the cost of electricity can be reduced. Because of the sufficient availability of solar radiation in Kathmandu Valley during winter season, underfloor heating with solar water heating can be a viable technology for residential buildings. So this paper is focused on identifying suitable system/or domestic radiant floor heating system. Compound parabolic concentrator (CPC) water heating system is more suitable for heating water because tracking system is not required and sufficient water temperature can be achieved. It is also found that more studies are necessary to make the system cost effective and suitable for the residential buildings in Kathmandu.

Recovery of Nutrients From Wastewaters Using Microalgae

In this chapter the relevance of microalgae-based processes for the recovery of nutrients contained in wastewaters is reviewed. The fundamentals of the process are discussed from the biological and engineering standpoints and it is shown that on this type of processes the nutrient recovery capacity is mainly a function of solar radiation availability. If adequately designed and operated up to 450 tCO2, 25 tN and 2.5 tP per hectare and per year can be fixed, producing up to 200 t/year of valuable microalgae biomass. The utilization of microalgae-based processes reduces to half the energy consumption of conventional wastewater treatment and allows recovering up to 90% of the nutrients contained into wastewater. Still the technology available (photobioreactors, harvesting, downstream) must be improved to reduce the land requirement and the hydraulic retention time, but current technology is ready to be demonstrated at large scale, so that the first initial facilities based on this technology have been recently developed. Moreover, this technology must be adapted to the different wastewater types, from sewage to manure. The major advantage of microalgae-based processes is the production of large amounts of valuable biomass, useful for the production of biofuels but much more interesting for animal feeding and agriculture uses, thus enhancing the productivity and sustainability of foods production.

Sustainable intensification of sugarcane production under irrigation systems, considering climate interactions and agricultural efficiency

Irrigation has been mentioned as one of the main strategies to increase sugarcane yield, but the challenge is how to make this opportunity in an environmentally compatible manner. The aim of this work is to assess the impacts of irrigation systems on sugarcane production not only from an agricultural point of view, but also from a perspective of the efficient use of land and water. Sugarcane yields under rainfed and irrigated conditions were simulated by a calibrated FAO Agroecological Zone Model over a 32-year period (1982–2013) across different Brazilian regions. As expected, higher yields were found for all regions under irrigated systems, but significant variations in terms of yield gains were observed amongst regions. While Petrolina showed the lowest yields (37.5 Mg ha−1) and Ribeirao Preto the highest ones (88.7 Mg ha−1) under rainfed conditions, the results were completely opposite in relation to irrigation scenarios. Petrolina showed the highest response to water supply (167.8 Mg ha−1), while Ribeirao Preto was less responsive to irrigation (145.7 Mg ha−1). The total water consumption or the efficiency of irrigation system is as important as the potential of each region to transform it into biomass, which is attributable to the high levels of solar radiation, photoperiod and air temperature. The data obtained herein highlight that irrigation systems reduced the inter-annual variability of yield (from 20% to 6%) and the land demand for sugarcane production (up to 78%), thus improving the water use and its efficiency (more biomass, less water). These findings provide new insights to decision makers in developing management strategies to further enhance the potential of sugarcane production when judiciously managed with irrigation in regions under low availability of water and high solar radiation and air temperatures.

A cost-optimal solar thermal system for apartment buildings with district heating in a cold climate

ABSTRACTFinding the global optimal combination of the main components for a solar thermal energy system is an important topic in utilising solar radiation in a cost-effective way. However, selecting an optimal solar thermal system in a cold climate condition is a challenging task due to the dependency on the heat demand and the limited availability of solar radiation. This research presents several sets of optimum combinations of a solar thermal collector and a hot water storage tank regarding energy efficiency and the life cycle cost. Since domestic hot water consumption forms the significant part of the heat demand in new energy efficient apartment buildings, the applied consumption information were extracted precisely according to measured data. The solar thermal system with cost-optimal component sizes was able to save district heat energy consumption up 24% to 34% and made 4 €/m^2 to 23 €/m^2 in financial profit.

Determining the Optimum Tilt Angles to Maximize the Incident Solar Radiation - Case of Study Pristina

Solar energy is derived from photons of light coming from the sun in a form called radiation. Solar energy finds extensive application in air and water heating, solar cooking, as well as electrical power generation, depending on the way of capturing, converting and distribution. To enable such application, it is necessary to analyze the horizontal tilt angle of horizontal surfaces – in order that when the solar energy reaches the earth surface to be completely absorbed. This paper tends to describe the availability of solar radiation for south-facing flat surfaces. The optimal monthly, seasonal, and annual tilt angles have been estimated for Pristina. The solar radiation received by the incident plane is estimated based on isotropic sky analysis models, namely Liu and Jordan model. The annual optimum tilt angle for Pristina was found to be 34.7°. The determination of annual solar energy gains is done by applying the optimal monthly, seasonal and annual tilt angles for an inclined surface compared to a horizontal surface. Monthly, seasonal and annual percentages of solar energy gains have been estimated to be 21.35%, 19.98%, and 14.43%. Losses of solar energy were estimated by 1.13 % when a surface was fixed at a seasonal optimum tilt angle, and when it was fixed at an annual optimum tilt angle, those losses were 5.7%.Article History: Received February 15th 2018; Received in revised form May 12th 2018; Accepted June 2nd 2018; Available onlineHow to Cite This Article: Berisha, Xh., Zeqiri, A. and Meha, D. (2018) Determining the Optimum Tilt Angles to Maximize the Incident Solar Radiation - Case of Study Pristina. Int. Journal of Renewable Energy Development, 7(2), 123-130.https://doi.org/10.14710/ijred.7.2.123-130

Una Revisión sobre Materiales para Almacenamiento de Energía Solar Térmica

Context: The energy and environmental panorama that our societies confront nowadays, demand for renew-able, clean and abundant sources of energy, not reliant on fossil fuels and detached from the geopolitical pressures the latter represent. In this scenario solar thermal energy arises as a viable and functional option. The main disadvantage of this emerging source of energy lies in the intermittent availability of solar radiation. Because of this difficulty, efficient processes for the storage of thermal solar energy becomes a highly relevant area of research. The aim of this paper is to present a survey on this topic.Method: A bibliographic review was carried out using the Scopus catalog. The search criteria for this purpose was defined using the following terms: solar+thermal+energy+storage+materials. This search pattern was applied to the title, abstracts and keywords of the contributions. Using the bibliometric tools of the citation database, the most cited documents were selected and the survey was developed.Results: A growing interest in the scientific community regarding this energy practice is evident starting from 2010. Characteristics, advances and trends in systems that use thermal energy storage materials are presented for sensible and latent heat, materials compound changeover phase, and finally thermo-chemical thermal storage materials.Conclusions: Improving the thermal conductivity of thermal storage materials is an important trend in current re-search. On the other hand, profitable practices for micro-encapsulated phase change materials and composite materials are analyzed. The optimization of thermo-physical properties as the melting point of thermal storage materials is explored with techniques such as eutectic mixtures and hydro-carbon chain length. Although the thermochemical materials are still in laboratory stage, they have a great potential as thermal storage materials in the future, given their large energy storage capacity per unit volume.

Dynamic simulation and thermoeconomic analysis of a novel solar cooling system for a triple-pressure combined cycle power plant

This paper presents the design of a novel high-temperature solar assisted triple-pressure level combined cycle power plant. The system includes innovative high-temperature flat plate evacuated solar thermal collectors, a double stage lithium bromide/water absorption chiller, pumps, heat exchangers, storage tanks, mixers, diverters, controllers and a triple-pressure combined cycle power plant. This novel layout uses high-vacuum non-concentrating flat plate solar thermal collectors driving a double effect absorption chiller, leading to an overall high coefficient of performance for the solar cooling section. The provided cooling energy is used to cool gas turbine inlet air to enhance system efficiency and electrical capacity. This effect is mainly performed during central hours of the day when the conventional gas-fired combined cycles dramatically suffer for efficiency and capacity reduction, as a consequence of the corresponding increase of external air temperature. Such increase is related to the higher availability of solar radiation. This technology may be a viable solution, especially for hot and dry areas, in terms of primary energy savings and increased revenues. This prototypal system was numerically analysed for a combined cycle with a rated electrical power of 99 MWe and an electrical efficiency of 56%, developing a dynamic simulation model and detailed thermo-economic optimizations. Special attention is also paid to the design of novel control strategies aiming at maximizing the solar cooling effect. The results of the dynamic simulations show a very high average thermal efficiency of the solar collectors, equal to 34%. Implications of the performed work allowed an increase of the power output up to 5.5% and a satisfactory payback period equal to 10.7 years.

An overview of the System of Rice Intensification for Paddy Fields of Malaysia

Objectives: To present a general overview of rice agronomic practices and transplanting operations by considering the interactions of soil, plant, and machine relationship in line with the System of Rice Intensification (SRI) cultivation practice. Methods: Some of the problems challenging Malaysian rice growers, as well as yield increase and total rice production in the last four decades, were first addressed and discussed. The trend in the world rice production between 1961 and 2014 was used to predict the production in 2020 and to show that Southeast Asian countries are expected to increase their production by 27.2%. Findings: A consistently increasing pattern from 3.1 tons/ha during 1981 to 4.1 tons/ha in 2014 was observed in the rice yield of Malaysia due to the advances in technology and improved farming operations coupled with integrated management and control of resources. Various literatures were reviewed and their findings of the best transplanting practices were summarized to discuss how SRI contributes to the production of higher rice yield with improved transplanting practices through a more effective root system. Our review shows that wider spacing, availability of solar radiation, medium temperature, soil aeration, and nutrient supply promote shorter Phyllochrons which increase the number of tillers in rice. In this regard, modification and development of a transplanter that complies with SRI specification require determination of optimum transplanting spacing, seed rate, and planting pattern to significantly improve yield. Improvement: It was concluded that for maximum yield, the SRI method in Malaysia should emphasize on planting of one seedling per hill with space of 0.25 m for optimum water consumption, nutrient and pest management. Keywords: Nursery Management, Paddy, Seedling, System of Rice Intensification, Transplanting

English

This study aimed to analyze the interactions between environmental variables and the occurrence of tree species in the understory of an Atlantic forest fragment in Southeastern Brazil. The vegetation data collection was carried out in ten locations, with trees having diameter at breast height (DBH) larger than 5 cm and with distinct physiographic characteristics, orientation and slope. The following variables were collected at each site: sum of the soil bases, soil moisture, leaf area index (LAI) and canopy transmissivity of photosynthetically active radiation (PAR). The interaction between environmental variables and vegetation was investigated employing the canonical correspondence analysis (CCA), using data from the natural regeneration (TNR) of forty-six species and the environmental variables of the locations studied. The Monte Carlo test showed that the correlation between TNR values for the species and environmental variables was statistically significant. The occurrence of four primary species groups was identified through this analysis. Considering the availability of solar radiation, one species group was observed to have occurred under the open canopy with high transmissivity of PAR, and another in locations with high LAI values and low PAR transmissivity. When soil variables were considered, we were able to distinguish two groups; a group of species showed preference for sites with fertile soil and high water content and another group that was more predominant in sites with drier soil, usually on steeper slopes. Key words: Brazilian Atlantic forest, environmental heterogeneity, photosynthetically active radiation, leaf area index.

Operation performance enhancement of single-double-effect absorption chiller

Absorption chillers constitute a valuable option for utilising solar energy. Specifically, when installed in tropical regions, this technology ideally matches the needs for refrigeration and air-conditioning because of the abundance of solar energy throughout the year. A single-double-effect absorption chiller combines the single and double-effect configurations to compensate for the unpredictable instantaneous availability of solar radiation and cooling load fluctuations. The operative performance of this system is strongly affected by internal parameters such as the absorber outlet solution flow rate and the solution distribution ratio, which connect the operability of the single and double-effect configurations. Therefore, these important parameters are currently used to maximise system performance while assuring its stability. This study discusses how the COP of a single-double-effect absorption chiller, for solar cooling applications in tropical areas, can be maximised (1.55 at full load, and up to 2.42 at 60% partial load) by manipulating those internal parameters. The simulation results were compared with the experimental data (field test data) and, by adopting the appropriate control method, showed an improvement of the system performance between 12 and 60% when compared to a corresponding double-effect configuration.

Performance Study of Small Capacity Solar Autonomous Absorption Air-Conditioning System Coupled with a Low-Energy Residential Building Under Batna (Algeria) Climate

Solar absorption cooling technology has enormous potential for air-conditioning applications as the need for cooling coincides mostly with the availability of solar radiation. Due to the geographical nature and vast territory of Algeria and the presence of many isolated rural areas, there is a great need for autonomous systems that use only solar energy without auxiliary boiler to meet the cooling demand in summer. In this study, we propose a dynamic simulation model for solar autonomous absorption air-conditioning systems developed using the TRNSYS-EES software. The model used to study the feasibility and evaluate the functioning of the system under Batna, Algeria weather conditions. The proposed system uses solar thermal flat plate collectors to drive a small capacity single-effect LiBr/water absorption chiller to meet the cooling demand of a typical low-energy residential building covering a total floor area of 120[Formula: see text]m2. A model of 4.5[Formula: see text]kW commercial absorption chiller has been modeled with EES software. The validation results showed excellent agreement between the prediction and the experimental data ([Formula: see text]) and proved the model ability to predict the performance of the chiller. The analysis of dynamic results indicates that the proposed system and selected size enable the chiller to work for a duration of up to 10[Formula: see text]h a day. This allowed ensuring a sufficient and continuous cold water supply (between 8[Formula: see text]C and 18[Formula: see text]C) and maintaining the comfort temperature between 26[Formula: see text]C and 28[Formula: see text]C.

On the design, modelling and analysis of multi-shelf inclined solar cooker-cum-dryer

A novel design of multi-shelf side loading inclined solar cooker-cum-dryer (ISCCD) is designed using single reflector North Facing Booster Mirror (NFBM) to improve the performance of both cooking and drying operations particularly in winter months. Innovative parallelepiped shape vessel (PSV) is designed (having longest inclined south facing wall) to further enhance the performance of ISCCD in cooking mode. Solar radiation capture model by ISCCD is used in developed thermal model for various interactive components such as; glass covers, chamber air, absorber plate, cooking vessel and vessel water while considering the effect of NFBM and experimentally validated at Ludhiana climate (30°N latitude), India. Volume to aperture area ratio along with size of PSV is optimized in such a way that ISCCD with three-shelves is capable of cooking three times more food as compared to the conventional horizontally placed solar cooker (HPSC). Due to optimized vessel design and NFBM effect, ISCCD can be effectively used in extreme winter conditions when maximum temperature during the day hovers around 15–20 °C (on sunny days) at latitudes >30°N for both cooking as well as drying operation when conventional HPSC and dryer (generally not fitted with booster mirror) do not perform well due to lower solar radiation availability. Stagnation test (first figure of merit F1) and sensible heat test (second figure of merit F2) were also computed and compared with HPSC to ascertain the performance of ISCCD. In drying mode, ISCCD was tested for drying gooseberry (Emblica officinalis) (local name amla) under natural as well as forced convention modes with and without the effect of NFBM. The Logarithmic drying model was found to be the best fit for drying gooseberry. Techno-economic analysis showed that in cooking mode ISCCD can be used to cook at least one meal per day for a joint family of 10 persons during 280 days in a year and can recover its cost within 65 months if compared with wood burning costs besides having the advantage of being used as an efficient dryer thereby saving the cost of second gadget. In terms of savings in biomass fuel burning, ISCCD can mitigate much higher CO2 emissions as compared to conventional HPSC.

Analysis of a micro photovoltaic/thermal – PV/T system operation in moderate climate

The paper analyses the possibility of application of PV/T systems in moderate climate conditions. Experimental part of research studies has been developed in Patras, Greece, in October–November. In that time climatic conditions in Greece are similar to summer (warmest) weather conditions in Poland. Some aspects of Polish climatic conditions, especially of solar radiation availability are presented. The liquid single glazed PV/T module has been selected for consideration as the most suitable for described climatic conditions. Experimental outdoor stand with such PV/T module has been designed and constructed to determine its energy performance. A mathematical model of the photovoltaic/thermal solar system operation is presented. Existing formula for determination of the PV/T temperature during its operation has been validated by experimental studies. As a result the correction - design factor has been introduced to the formula. It helps to take into account the design (number of covers) of the PV/T module, when its energy performance and operation are determined through simulation studies. Simulation studies of the dynamics of a microscale PV/T system supplying energy (electricity and heat to Domestic Hot Water system) to a standard single-family house has been performed using own numerical code. Selected results of simulation studies of the operation of different cases (sizes) of PV/T systems are described. Simulation studies of operation of the PV/T systems in micro scale application in high latitude countries show, that for 2 months of a year, in December and January, more electrical than thermal energy is generated by the PV/T system. In summer problems with too high temperature of the working fluid of the PV/T module can occur. As a result, the electrical efficiency decreases. In Polish climatic conditions a PV/T system should be provided with a continuous heat removal system to assure efficient operation of the system.