Sunny Conditions Research Articles

Karakteristik Temperatur Pada Permukaan Sel Surya Polycrystalline Terhadap Efektifitas Daya Keluaran Pembangkit Listrik Tenaga Surya

Devices that can convert sunlight energy to electrical energy with photovoltaic effect process made of semiconductors are better known as solar cells. Photovoltaic (PV) or better known as solar power plant (PLTS) is also concerned with several factors to maximize solar energy into electrical energy such as the influence of weather, humidity, temperature of solar cell position and wind direction contained on the surface of solar cells. In this study, this solar cell (photovoltaic) was diagnosed as poly-crystalline during sunny and cloudy weather conditions. The results obtained by the test showed the influence of temperature from the surface of solar cells on the value of output power. Maximum power (Pout) at 11.40 WIB with a slope angle of 35° and a temperature of 47.6°C with an output power value of 100.562 Watt. So it can be said that the temperature is influenced by the intensity of solar radiation that will make the power (Pout) increase, the condition of the poly-crystalline solar module will work optimally at a temperature of about 35 °C - 50 ° C measured on the surface of solar cells.

Modeling the impacts of diffuse light fraction on photosynthesis in ORCHIDEE (v5453) land surface model

Abstract. Aerosol- and cloud-induced changes in diffuse light have important impacts on the global land carbon cycle, as they alter light distribution and photosynthesis in vegetation canopies. However, this effect remains poorly represented or evaluated in current land surface models. Here, we add a light partitioning module and a new canopy light transmission module to the ORCHIDEE (Organising Carbon and Hydrology In Dynamic Ecosystems) land surface model (trunk version, v5453) and use the revised model, ORCHIDEE_DF, to estimate the fraction of diffuse light and its effect on gross primary production (GPP) in a multilayer canopy. We evaluate the new parameterizations using flux observations from 159 eddy covariance sites over the globe. Our results show that, compared with the original model, ORCHIDEE_DF improves the GPP simulation under sunny conditions and captures the observed higher photosynthesis under cloudier conditions in most plant functional types (PFTs). Our results also indicate that the larger GPP under cloudy conditions compared with sunny conditions is mainly driven by increased diffuse light in the morning and in the afternoon as well as by a decreased vapor pressure deficit (VPD) and decreased air temperature at midday. The observations show that the strongest positive effects of diffuse light on photosynthesis are found in the range from 5 to 20 ∘C and at a VPD < 1 kPa. This effect is found to decrease when the VPD becomes too large or the temperature falls outside of the abovementioned range, which is likely due to the increasing stomatal resistance to leaf CO2 uptake. ORCHIDEE_DF underestimates the diffuse light effect at low temperature in all PFTs and overestimates this effect at high temperature and at a high VPD in grasslands and croplands. The new model has the potential to better investigate the impact of large-scale aerosol changes and long-term changes in cloudiness on the terrestrial carbon budget, both in the historical period and in the context of future air quality policies and/or climate engineering.

The simple urban radiation model for estimating mean radiant temperature in idealised street canyons

Thermal comfort is an important component of health-related urban well-being (UrbWellth) of the urban population. Outdoors in sunny conditions the human thermal environment is strongly influenced by radiation fluxes, which are often expressed as a mean radiant temperature (Tmrt). In an urban environment Tmrt is, especially in sunny conditions, strongly influenced by the building morphology due to shading and reflection of radiation. To model these morphological effects within an urban system model for UrbWellth, a simple model for Tmrt is required that simplifies the actual urban environment to reduce computational costs but still considers the most important aspects of Tmrt variability within a city. To do so, within this paper the open-source and modular Simple Urban Radiation Model (SURM) is presented. SURM is validated with respect to different calculation methods of both view factors and radiative fluxes as well as to radiation modification by buildings. The results indicate that SURM models radiative fluxes and radiative influences of buildings sufficiently accurate to be applicable as one component of an urban system model for sunny conditions.

The use of satellite and surface observations for initializing clouds in the HARMONIE NWP model

AbstractThe study tests and further develops a previously presented method for adjusting initial clouds in the HARMONIE mesoscale numerical weather prediction (NWP) model. The method uses satellite‐observed cloud properties from the Nowcasting and very short range forecasting Satellite Application Facility (NWCSAF) together with ground‐based synoptic stations (SYNOP) observations, adjusting the humidity profile of the model based on the available cloud information with the overall aim to improve the forecast, in particular as regards clouds and solar radiation. A reference set‐up of the HARMONIE model is used as a baseline against which the cloud initialization experiments are compared. All HARMONIE experiments are run for July 2016, with a model run starting at 06Z each day. The HARMONIE outputs are compared with cloud fraction and solar radiation observations from ground‐based stations, while satellite cloud observations are also used for inspecting the behaviour of the forecasts. The performance of other generally used verification parameters is also studied. The results as regards clouds are encouraging. Symmetrical extremal dependence index (SEDI) skill scores show improvement in initial cloud conditions in 84% and 74% of the cases, when evaluated for cloud‐free (0–1 octas) and cloudy conditions (7–8 octas), respectively. The improvement lasts 2–4 hr into the forecast. Other parameters, however, show somewhat degraded skill as compared with the reference model run, while for solar radiation, the cloud initialization scheme exhibits somewhat ambiguous results. The distribution of solar radiation values is improved for relatively sunny conditions, while at the other end of the distribution, the cloud initialization scheme produces too many cases with relatively strongly attenuated radiation.

Shade alters savanna grass layer structure and function along a gradient of canopy cover

AbstractAimIn savannas, a grass‐dominated ground layer is key to ecosystem function via grass–fire feedbacks that maintain open ecosystems. With woody encroachment, tree density increases, thereby decreasing light in the ground layer and potentially altering ecosystem function. We investigated how light availability can filter individual grass species distributions and whether different functional traits are associated with response to a shade gradient in a landscape experiencing woody encroachment.LocationSavanna–forest mosaic in the Cerrado domain, southeastern Brazil.MethodsAlong an encroachment gradient of increasing tree leaf area index (LAI) and shade, we determined how changing light availability alters grass diversity and ground layer structure relative to grass cover and grass functional traits (photosynthetic pathway, underground storage organs, bud protection and traits related to grass shape, size and leaf dimensions).ResultsIncreasing shade led to a decrease in grass cover and grass species richness, and also compositional and functional changes. We found that where tree LAI reached 1, grass cover was reduced by 50% and species richness by 30%. While C4 grass species abundances decreased with increasing shade, the opposite pattern was true for C3 grasses. There were only small differences in light preferences among C4 subtypes, with phosphoenolpyruvate carboxykinase (PCK) species tolerating slightly more shaded conditions. Persistence of some C4 species under more shaded conditions was possible, likely due to an ability to store starch reserves via underground storage organs.ConclusionsWoody encroachment changes diversity and structure of the grassy layer that is critical to the functioning of savanna ecosystems, highlighting the dependence of the diverse grass layer on open and sunny conditions. Our results suggest a threshold of tree cover close to LAI ≈ 1 as being critical to cerrado grassy layer conservation.

Artificial neural network models for global solar energy and photovoltaic power forecasting over India

ABSTRACT For design and development of solar-based photovoltaic (PV) system, accuracy in obtaining data of solar energy has been a prime concern. Forecasting of global solar energy in clear or sunny weather conditions are easily calculated; however, the challenge lies in estimating under the impact of foggy and cloudy conditions. Therefore, this research investigates and presents the Artificial Neural Network (ANN) models for global solar energy forecasting for distinct sky-conditions such as sunny, hazy, partly, and fully cloudy conditions. This research further applied for distinct climatic conditions namely composite, warm & humid, moderate, hot & dry, and cold & cloudy climate zone using meteorological parameters. Further, PV power forecasting has been essential for planning the operating capability of energy systems and its reliability. The present work explores the implementation of proposed model for short-term photovoltaic power forecast in solar energy systems. Lastly, comparative analysis of the developed model with other neural network models are carried out using statistical evaluation indices. It has been observed from the overall analysis that by using the Radial-Basis-Function-Neural-Network (RBFNN) model, a significant reduction in error has been noticed as compared to other methods. Further, it is noted that the sunny model provides improved performance for hot & dry climate zone; hazy model gives favorable output for composite climate zone; partly cloudy model is favorable for warm & humid climate zone; and lastly, fully cloudy model provides favorable results for cold & cloudy climate zone. The model has been implemented for broader application series and it has been observed that for short-term photovoltaic power forecasting under composite climatic zone, hazy model emerges out to provide better performance with Mean Absolute Percentage Error (MAPE) of 0.0019% followed by sunny, partly, and fully cloudy model with MAPE 0.024%, 0.054%, and 0.109% respectively. The models presented in this research will be useful for scholars to design and engineer the solar energy systems.

Data-Driven Day-Ahead PV Estimation Using Autoencoder-LSTM and Persistence Model

Inherent variability in photovoltaic (PV) and associated impacts on power systems is a challenging problem for both the PV owners and the grid operators. Existing statistical and machine learning algorithms typically work well for weather conditions similar to historical data. However, uncertain weather conditions pose a great challenge to the estimation accuracy of the estimation models. With the enhanced integration of intelligent electronic devices and the realization of associated automation in the power grid, renewable energy data are becoming more accessible, which can be utilized by deep learning models and improve the PV power generation estimation accuracy. In this article, a hybrid deep learning model driven by external weather data is proposed to do day-ahead PV output forecasting at 15-min interval. The proposed model is motivated by the recent advancement of long-short-term-memory networks and autoencoder, which estimates uncertainties in sequence while making the prediction for complex weather conditions. Meanwhile, the persistence model is used to predict continuous sunny weather conditions. The forecasting result is validated with data from multiple locations.

Linkages between Climate, Radial Growth and Defoliation in Abies pinsapo Forests from Southern Spain

Systematic forest networks of health monitoring have been established to follow changes in tree vigor and mortality. These networks often lack long-term growth data, but they could be complemented with tree ring data, since both defoliation and radial growth are proxies of changes in tree vigor. For instance, a severe water shortage should reduce growth and increase tree defoliation in drought-prone areas. However, the effects of climatic stress and drought on growth and defoliation could also depend on tree age. To address these issues, we compared growth and defoliation data with recent climate variability and drought severity in Abies pinsapo old and young trees sampled in Southern Spain, where a systematic health network (Andalucía Permanent Plot Network) was established. Our aims were: (i) to assess the growth sensitivity of old and young A. pinsapo trees and (ii) to test if relative changes in radial growth were related with recent defoliation, for instance, after severe droughts. We also computed the resilience indices to quantify how old and young trees recovered growth after recent droughts. Wet-cool conditions during the prior autumn and the current early summer improved the growth of old trees, whereas late-spring wet conditions enhanced the growth of young trees. Old trees were more sensitive to wet and sunny conditions in the early summer than young trees. Old and young trees were more responsive to the Standardized Precipitation-Evapotranspiration Index drought index of June–July and July–August calculated at short (one–three months) and mid (three–six months) time scales, respectively. Old trees presented a higher resistance to a severe drought in 1995 than young trees. A positive association was found between stand defoliation and relative growth. Combining monitoring and tree ring networks is useful for the detection of early warning signals of dieback in similar drought-prone forests.

Pollen longevity, flowering phenology, and seedbank persistence of Camelina sativa (L.) Crantz and congenic species

The potential for wide-scale adoption of genetically engineered (GE) Camelina sativa (L.) Crantz in North America has raised ecological concerns of gene flow to its weedy relatives. The objectives of this study were to determine the pollen longevity, flowering phenology and seedbank persistence of C. sativa and congenic species. Percent pollen germination of all Camelina species was reduced with increasing temperature and exposure time. Pollen germination was not observed for all taxa after 72 h between 20−40 °C. Weather conditions had a significant effect on pollen longevity. Under cloudy conditions, all taxa pollen had a longer period of longevity (half-life: 0.6−0.8 h) than sunny conditions (0.3−0.4 h). Under both conditions, C. sativa, Camelina alyssum (Mill.) Thell., and Camelina microcarpa Andrz. Ex DC. pollen had a longer period of longevity than Camelina hispida var. grandiflora (Boiss.) Hedge, Camelina laxa C. A. Mey, and Camelina rumelica Velen., but pollen germination was not observed after 5 h exposure. The flowering phenology of C. sativa, C. microcarpa, and C. alyssum behaved similarly, which was different from C. hispida, C. laxa, and C. rumelica. Flowering synchrony among taxa was observed, facilitating pollen-mediated gene flow among taxa. Seeds of C. sativa, C. alyssum, and C. microcarpa did not exhibit dormancy in the soil, but the germination ability of C. sativa throughout the growing season raises the ecological concerns of gene flow from C. sativa volunteers. This new information on pollen longevity, flowering phenology, and seedbank persistence will be helpful for creating containment and coexistence strategies between GE and Non-GE C. sativa, isolating field trials, and managing GE C. sativa volunteers associated weed problems.

Daytime measurements of bioaerosol simulants using a hyperspectral laser-induced fluorescence LIDAR for biosphere research

A new compact home-built hyper-spectral laser-induced fluorescence (LIF) light detection and ranging (LIDAR) system is presented that can detect and identify bioaerosol clouds in an open atmosphere in daylight up to a distance of 3−4 km. The system is based on a 266 nm laser source and a dual-stage micro-channel plate intensified charge-coupled device sensor, which provides a high-resolution fluorescence spectrum with the sensitivity of a single photon counting imaging detection at a 10 Hz repetition rate. Controlled remote sensing experiments on biological simulants in the aerosol-phase within an enclosed chamber (ΔR=1.2 m) were conducted from a short distance of ∼170 m. A meticulous comparison between the remote fluorescence signal detected by the system and the instantaneous concentration and particle size distribution of the bioaerosol inside the chamber detected by an aerodynamic particle sizer yielded a threshold of ∼20 and 137 μgr s m-3 for the spectral identification of tryptophan and ovalbumin, respectively. This showed that the LIDAR can measure environmental airborne biological aerosol remotely in the daytime and can be utilized as a real-time biosphere research tool. Next, the system was tested in open atmospheric field campaigns in the Israeli desert during the day. It successfully detected bioaerosol clouds at up to 2.5 km in strong wind and sunny conditions. These empirical detection and identification results provide robust estimates that a biological cloud can be sensed at a distance of ∼ 4 km.

Differential Distribution of Flavonoids and Phenolic Acids in Leaves of Kalanchoe delagoensis Ecklon & Zeyher (Crassulaceae).

Kalanchoe delagoensis is adapted to intense solar irradiation, drought, and heat, partially due to the presence of phenols, important photo-protective compounds and antioxidants. This study aimed to evaluate the distribution of flavonoids and phenolic acid derivatives throughout the erect-tubular leaves of K. delagoensis. Specimens grown under sunny conditions were used for histochemical and high-performance liquid chromatography coupled with diode array detection (liquid HPLC-DAD) analysis. The NP (2-aminoethyl diphenylborinate) test suggested the presence of phenolic acids throughout the leaf blade below the epidermis and in chloroplasts, mainly in the leaf base. Flavonoids were detected specifically in chloroplasts, on the adaxial side of the middle third and at the leaf apex, near the meristematic cells. There was a tendency of flavonoid accumulation from the middle third to the apex, especially surrounding the gem, while phenolic acids were observed mainly in the base. This can be explained by the more exposed leaf apex and to the presence of apical buds (high production and regulation sites of ROS). The HPLC-DAD analysis showed different classes of flavonoids and phenolic acid derivatives in the leaf extracts, agreeing with the NP test results. This is the first time that the substitution of phenolic acids by flavonoids from the leaf base to the apex has been described.

How mulching and canopy architecture interact in trapping solar radiation inside a Mediterranean greenhouse

This work evaluates roles and interactions of ground albedo (ag) and canopy architecture in capturing solar radiation inside Mediterranean greenhouses. Both incident and reflected solar radiation were measured over the ground surface and the greenhouse roof cover during a series of greenhouse experiments where common types of mulch and crop architecture were combined. In the experiments without crop around winter, changes in the daily mean ag from 0.06 to 0.38 induced changes in the greenhouse cover albedo (ac), which ranged from about 0.20 to 0.42. In measurements carried out around winter, both the ag and ac decreased when the ratio of the outdoor diffuse-to-solar radiation increased, independently of the ground surface, indicating that a higher percentage of solar radiation was trapped by the greenhouse under diffuse than under sunny conditions. In crops grown horizontally (not vertically trained), the effect of ground mulching over ag vanishes progressively with the increase in leaf area of the crops, resulting in an asymptotic trend of ag close to 0.23 at full ground covering, independently of the mulch type. In crops grown with high-wire production systems (plants grown in separated rows with the canopy distributed vertically up to 1.5–4.0 m high), asymptotic ag values were also reached but they were lower and dependent on the mulch type and the canopy architecture (0.08 for with black mulch and 0.12 to 0.19 with a gravel mulch). Then, crops with high-wire production systems, common in greenhouses, presented a higher efficiency in trapping solar radiation inside greenhouses. A model, which predicts fairly well the ac from the knowledge of ag and the cover shortwave reflectance, was proposed and used.

Wide variation in the suboptimal distribution of photosynthetic capacity in relation to light across genotypes of wheat.

Suboptimal distribution of photosynthetic capacity in relation to light among leaves reduces potential whole-canopy photosynthesis. We quantified the degree of suboptimality in 160 genotypes of wheat by directly measuring photosynthetic capacity and daily irradiance in flag and penultimate leaves. Capacity per unit daily irradiance was systematically lower in flag than penultimate leaves in most genotypes, but the ratio (γ) of capacity per unit irradiance between flag and penultimate leaves varied widely across genotypes, from less than 0.5 to over 1.2. Variation in γ was most strongly associated with differences in photosynthetic capacity in penultimate leaves, rather than with flag leaf photosynthesis or canopy light penetration. Preliminary genome-wide association analysis identified nine strong marker-trait associations with this trait, which should be validated in future work in other environments and/or materials. Our modelling suggests canopy photosynthesis could be increased by up to 5 % under sunny conditions by harnessing this variation through selective breeding for increased γ.

Accuracy of Mean Radiant Temperature Derived from Active and Passive Radiometry

The concept of the mean radiant temperature (Tmrt) allows the study of radiative exchanges between a human and its environment. It presupposes that the radiant effects on the person of the actual environment, which is generally heterogeneous, and the virtual environment, which is defined as homogeneous, are identical. ISO 7726 specifies the required accuracy in Tmrt as input of rational thermal indices, outdoors ±5 (K). Tmrt accounts for the radiant heat absorbed by skin/clothing from the shortwave (SW) and longwave (LW) spectral bands. Most of the radiant components are isotropic. However, there are anisotropic SW components; namely the direct irradiance and under clear or partly obstructed skies a significant circumsolar fraction (fcs) in the diffuse irradiance. Both originate from the close proximity of the solar disk. This study highlights the effect of fcs on Tmrt. In the scope of human biometeorology a standing body posture is standard. For unidirectional irradiances its radiant cross-section varies dependent on the solar altitude. Active radiometry in deriving Tmrt is based on measured irradiances. One method is the Klima-Michel-Modell (KMM) that uses readily available measurements from standard meteorologically radiant observations. KMM references Fanger’s area projection factors that are derived from precise measurements of real humans. Thus, KMM serves as reference in evaluation of further methods. One is the six-directional instrument (Tmrt,r,6−Dir). Slightly simplifying a standing human, it represents a subject as a rectangular solid. Tmrt,r,6−Dir is derived based on measured irradiances incident on the vertical and horizontal planes. In passive radiometry the energy balance equation of a black globe thermometer is solved that leads to Tmrt,Tg,BG. fcs significantly impacts Tmrt with noticeably reduced values for high and increased for low solar altitudes. Hence, accounting for fcs is essential for the accuracy of Tmrt. For KMM an extension to an existing algorithm is provided in order to include fcs into the Tmrt calculation that results in Tmrt,r,KMM. For Tmrt,r,6−Dir the radiant cross-section of the solid depends to a minor extent on its azimuth relative to the solar azimuth. As a result Tmrt,r,6−Dir slightly scatters compared to Tmrt,r,KMM. However, it remains within ±2 (K). Tmrt,Tg,BG compared to Tmrt,r,KMM complies only at night with the ISO 7726 bin of ±5 K. Tmrt,Tg,BG significantly overestimates Tmrt,r,KMM during the daytime, because of its greater SW absorptance compared to skin/clothing and to a smaller extent because the standing posture is represented by a sphere. Particularly in sunny conditions, Tmrt,Tg,BG is subject to considerable variance. Thus, outdoors during the daytime, Tmrt,Tg,BG is unable to serve as an appropriate input for the calculation of rational-based thermal indices.

Power feedback strategy based on efficiency trajectory analysis for HCPV sun tracking

Abstract This paper presents a control strategy for sun trackers which adapts continuously to different sources of error, avoiding the necessity of any kind of calibration by analyzing the produced electric power to sense the position of the Sun. The proposed strategy is able to meet the strict specifications for HCPV sun trackers despite of mechanical uncertainties (misalignments in the structure itself, misalignment of the solar modules with respect to the wing, etc.) and installation uncertainties (misalignments of the platform with respect to geographical north). Experimental results with an industrial-grade solar tracker showing the validity of the proposed control strategy under sunny and moderate cloudy conditions, as well as with different installation precisions by un-calibrating the system on purpose are exposed.

Evaluating Urban Geometry Impacts on Incident Solar Radiation on Building Envelopes

The present study investigated the impacts of urban geometry on incident solar radiation on building envelopes. A three-dimensional model was developed and applied to examine these relationships, with implications for building landscapes as a potential heat source for urban heat islands. In the model, we classified building envelopes into three types, including ground, roofs, and building facades. Satisfactory model performance was confirmed by comparing measured and predicted incident solar radiation results. Furthermore, we developed the Incident Solar Radiation Prediction Index (ISRPI) to address relationships between urban geometry and incident solar radiation. Our overall results showed the solar irradiance incident on building envelopes was significantly affected by urban geometry. Building facades consistently shared a large amount of the building landscape’s total surface area and therefore determined more influence on variation in incident solar radiation. Weather conditions showed strong influence on incident solar radiation, primarily due to variation in atmospheric transmittance. Diffuse radiation demonstrated a larger share of incident solar radiation on the cloudy sampling day. ISRPI, which cumulatively combined the strengths of several traditional urban morphological metrics, exhibited a strong linear relationship with incident solar radiation under sunny and cloudy weather conditions. This index provided a more convenient approach to estimate the spatial-temporal variations of solar radiations at urban scale.

Light regimen-induced variability of photosynthetic pigments and UV-B absorbing compounds in Luzula sylvatica from Arcto-Alpine tundra

The aim of this study was to evaluate the effects of different in situ light regimen on ecophysiological parameters of Luzula sylvatica leaves. Plants of L. sylvatica grown under natural sunny and shade conditions in arcto-alpine tundra were analyzed with respect to their leaf anatomy, content of photosynthetic pigments, UV absorbing compounds and phenanthrenoid compounds. Relationship between chlorophyll concentrations (Chla+b) and SPAD values was determined for sun and shade leaves measured repeatedly within summer and autumn seasons 2019 and 2020. Pooled data showed curvilinear Chla+b to SPAD relationship with the highest Chla+b and SPAD values found for shade leaves. Sun leaves had higher UV-B absorbing compounds contents than shade ones. The HPLC-DAD analysis revealed significant amount of soluble flavonoids in Luzula sylvatica leaves, amongst others the flavone-luteolin and its derivatives (e.g. tentatively identified luteolin-methyl-glucoside and luteolin-glucoside). The accumulation of luteolin based compounds in sun acclimated leaves is also plausible explanation for the higher antioxidant activity determined in sun leaf extraxts. Such response of flavonoid metabolism may help L.S. to cope with excessive-light stress through UV-attenuation mechanism and ROS scavanging. Additionally, phenanthrenoid compounds contents in L. sylvatica leaves were determined. Altogether, 9 phenanthrenoid compounds were identified by HPLC-HRMS. Their content was markedly different (up to the factor of 5) between sun and shade leaves of L.sylvatica.

Rancang Bangun Sistem Conditioining Udara Berbasis IoT pada Studi Kasus Tanaman Selada Hidroponik

Air temperature and humidity as well as water temperature are very important environment variables in planting DFT hydroponic lettuce plants in a greenhouse. Controlling and monitoring the temperature and humidity generally still done manually by farmers. This problem can be solved by building an air conditioning system that implements the concept of the Internet of Things, which plays a role in automation control of actuators, and MQTT protocols as its data communication medium. Based on the test results, the system has been able to perform measurement and conditioning of air temperature and humidity, as well as water temperature in the greenhouse automatically. Comparison of observation and test result data with sunny weather conditions, showing that the average and maximum value of air and water temperature on test, lower compared to observation data. While the average and minimum value of humidity in the test are higher than the observation data.

Experimental investigation of thin-film solar cells as a wearable power source

ABSTRACT In this paper, a design for a wearable solar energy harvesting system with an embroidered electrical circuit is proposed. The hybrid simulation method is carried out by using MATLAB/Simulink and LTSpice simulation software’s to extract the unknown electrical parameters of the multi-junction solar cell. A DC-DC boost converter (LTC3105) with MPPC is experimented to step up the solar cell voltage to 5 V. The solar energy harvester model achieves optimum simulated results in the LTSpice software with MPPT for both sunny and artificial shading conditions. The maximum conversion efficiency of the solar energy harvesting system with MPPC is 73.46 with an output voltage of 5 V and 68.29 at 4.10 V output voltage for flat and bent conditions, respectively. The fabricated system is tested in various conditions such as flat, bent condition with radius of 5.5 cm and artificial shading. The fabricated flexible solar cell power source can easily supply the power to wearable electronic, wireless sensors, and biomedical sensors. The solar cell and boost converter are integrated with jeans textiles to make whole system as wearable one and electrical connections are embroidered with conductive yarn. The fabricated wearable solar cell power source can easily supply the power to wearable biomedical sensors.

The maintenance of prefabricated green roofs for preserving cooling performance: A field measurement in the subtropical city of Hangzhou, China

Urban temperature increase is a critical problem for many cities. Green roofing is an approach to mitigating urban temperature increase, while the maintenance of the green roof for stable cooling potential has been less studied. Therefore, this study aims to investigate the cooling performance of prefabricated green roof for maintenance purposes. Focusing on the cooling and humidifying performance of the green roof, this study is to understand the influence of (i) vegetation species, (ii) weather condition and (iii) watering. This study was experimentally performed in the subtropical city of Hangzhou, China in the summer season, with three local vegetation species including Pomegranate, Bermuda grass and Sedum lineare. Results indicate that under sunny conditions, the Pomegranate roof was favourable with the best diurnal cooling and humidifying effects, the Bermuda grass roof could be acceptable while the Sedum lineare roof is not suggested. In comparison, all green roofs could maintain diurnal cooling and humidifying effects under cloudy conditions. Watering is critical to green roof cooling and humidifying effects. Without watering, all green roofs could elevate air temperature and dry surrounding environment and could die. The Pomegranate should be watered before 15:00 under sunny condition, while both Bermuda grass and Sedum lineare roofs should be watered before noon. Moreover, nocturnal watering makes slight differences to green roof cooling and humidifying effects. Overall, this study helps understand the green roof cooling and humidifying effects and it can instruct green roof management and maintenance.