To obtain significant increases in the Power Conversion Efficiency (PCE) of solar cells, we argue that the substitution of the state-of-the-art one- and two-dimensional cell optimizations, by the simultaneous improvement of multiple material properties is of substantial advantage. In this context, researchers should know, which combined material properties and cell design parameters result in the highest efficiency increase. For the same objective, it is also of importance to know, which ideal relationships in-between these variables have to be adjusted. Such knowledge becomes available by simulations and numerical optimizations, which we present for a Perovskite Solar Cell (PSC) in a hypercube space of model variables. We prove that its PCE increases principally because of the nonlinearities inherent to its mathematical model, and therefore, we elucidate the importance of the multidimensional variable improvements in the PSC’s optimization. We increased the PCE to a value of at least 27.6% by simultaneous improvements of the cell’s material properties, and light trapping, for a large range of absorber layer thicknesses, from t₀ = 160 to 400 nm. The lower thickness results in a significant reduction of the device’s Pb content.

This paper presents an analysis of spectral impacts on mc-Si and new generation CdTe in two distinct regions of Brazil: Florianópolis-SC (27°S, 48°W) in the South, and Assu-RN (5°S, 37°W) in the Northeast. As utility-scale PV power plants are progressively being deployed in the Brazilian Northeast, the need for evaluation of the spectral effects of local blue-biased spectra on the energy yield of different PV technologies arises, as well as the need for spectral correction of field peak-power measurements done during commissioning and system performance tests. Considering the high cost of adequate spectral measurement equipment, this paper proposes a new approach for the estimation of spectral impacts without the need for in loco measurements. The proposed methodology consists of the use of satellite data acquired from NASA's Giovanni platform as inputs for the SMARTS 2.9.5 spectra model. Results for measured spectra showed that, for both locations, new generation CdTe (i.e. First Solar Series 4 and 6) has significant spectral gains: up to 10% for Assu-RN (Northeastern Brazil) and 2% for Florianópolis-SC (Southern Brazil). A seasonal variation could also be detected for the Florianópolis site, with lower spectral gains for CdTe - and higher for mc-Si - close to the Southern Hemisphere’s winter solstice, due to higher air mass values and lower precipitable water content of the atmosphere. The proposed method using Giovanni data and SMARTS spectra modeling produced very similar spectra to those measured for clear days in the field at both sites, yielding good results for the calculation of spectral factors for both mc-Si and CdTe. For days with a higher diffuse fraction the results were not as satisfactory, as expected. The proposed method was also applied to instantaneous measurements for three different times (and AM values) of the day for Florianópolis: 9:00, 12:00 and 15:00, yielding satisfactory results for IV curve spectral correction.

In contrast to the decades-long accumulated experience of photovoltaic (PV) installations in more temperate climates, the effects of some extreme operating temperatures and extreme solar irradiance levels start to become more noticeable with the uptake of large-scale PV in the sunbelt regions of the world. One such effect is caused by extreme solar overirradiance events, which up to now have been reported in the literature much more for their scientific interest than as a potential problem affecting the operational performance of PV power plants. Solar overirradiance events with a time span of tens of seconds or minutes are associated with the high operating temperatures prevailing in the field at many sites where utility-scale PV power plants start to become widespread, deleterious effects can be observed, which will negatively impact the performance of these generators. Using irradiance data from seven solar measuring stations deployed over distinct regions in Brazil, many of which are hosting megawatt-scale PV power plants, this paper reports on several extreme solar overirradiance events, with measured values above 1367 W/m² up to 1845 W/m², lasting from many seconds to a few minutes. Analysis of impacts and consequences from these events on the operational performance of PV generators are addressed, mainly focused on combiner box fuses, inverter overload losses, and inverter maximum power point tracker.

This study is aimed at performing and analyzing the inverter sizing optimization process for large-scale grid-connected solar photovoltaics (PV). The local solar resource was evaluated and compared to the available satellite data. Analyses of the solar irradiance distribution and its potential effects on inverter sizing were performed. The performance of five different, commercially-available PV module technologies was also evaluated by means of remote data analysis of irradiation and temperature, as well as electrical parameters. This was performed using the metrics of energy yield and performance ratio (PR) for PV systems. A methodology was developed for estimating the optimal inverter sizing in the region considering overload losses and economic aspects, aiming at the optimization and cost reduction of PV-generated electricity. Considering the five technologies, the mean yield was 150 kWh/kWp on a monthly basis. The annual PR ranged from 77% to 85% depending on technology. The local solar resource, measured during three years, was compared to five distinct satellite-derived solar databases. Cloud enhancement and cloud edge effects were observed through the monthly solar irradiation distribution over the three years of measurements. Around 28% of the incident annual irradiation was at irradiance levels at or above 1000 W/m². The methodology developed for the optimal inverter loading ratio (ILR) was applied over one full year of solar generation data for the five technologies. It was observed that for inverter loading ratios commonly used on utility-scale PV power plants (around 120%), the overload losses varied from 0.3% to 2.4%, depending on technology. The optimal ILR for the more traditional crystalline Si PV technology was estimated to be 126%.

This study evaluated the outcome differences when adopting five different solar irradiation databases on the sizing of hybrid solar photovoltaic-diesel generators designed to supply electricity to isolated minigrids. To do this, the two most widely adopted photovoltaic (PV) simulation packages in the market, namely PVsyst® and HOMER Energy® were used. The different origins, data timespan, space and time resolution, of the five most relevant solar irradiation databases available for the region were compared. A case study was presented to illustrate the influences of the solar irradiation database and the solar simulation tool on the resulting PV generator. Furthermore, the hourly behavior of the energy supply to an existing load in a minigrid in the Brazilian Amazon was evaluated, together with the savings in diesel obtained with the resulting PV generator. Evaluating the five options of solar radiation databases, for the same PV plant configuration, variations of up to 19.7% were found in the expectation of PV generation. When the simulation software package was varied, the combined effect (radiation database X PV system sizing tool) showed differences of up to 20.6%. This demonstrates that despite having different algorithms, computational tools have a small influence (less than 1%) on results. These combined differences, taking into account the load curve behavior and the total diesel generation capacity installed at the site, resulted in over 100% differences in the optimum PV generator size in the case study. The total savings in diesel fuel, over a 15-years period, ranged from $ 6.5 million to over $ 16 million (>2.5 times) for the smallest PV system. This demonstrates the importance of the correct choice of database. These evaluations can be extended to minigrids of any size elsewhere. The novelty and originality of this study is to demonstrate and quantify for the first time the influence of the solar radiation database and the PV simulator package on the sizing of PV-diesel generators. The consequences of this study are not only of scientific and academic importance, but of economic and commercial interest as well.

Utility-scale photovoltaic (PV) generation is being ramped-up in Brazil in recent years, as a result of intense price reductions. Extreme operating temperatures, high humidity levels, and a blue-biased distribution of irradiance in comparison with the standard ASTM G-173 spectrum, lead to contrasting operational outputs of the various commercially-available PV technologies. The performance assessment of six different PV technologies installed at eight different climatic regions in Brazil is presented. This R&D project evaluates eight identical, 54 kWp Evaluation Sites (ESs), all with the following PV technologies: amorphous-silicon (a-Si), microcrystalline-silicon (μc-Si), cadmium-telluride (CdTe), copper-indium-gallium-diselenide (CIGS), mono- and multi-crystalline silicon (c-Si and m-Si). All installations operate at a fixed-tilt equal to the corresponding local latitude. Electrical and environmental parameters at all sites are measured continuously at 1-s intervals. Results show a detailed energy loss analysis for all technologies. Thin-film PV modules with a low temperature-coefficient of power presented superior performance. Crystalline silicon modules revealed intense degradation in areas with high relative humidity and temperature. Cloud-edge and cloud-enhancement effects of solar irradiance resulted in irradiance peaks of 1823 W/m², with long overirradiance events which lasted many minutes over 1600 W/m², resulting in frequent blowing of string fuses when manufacturers maximum fuse ratings were observed.

The implementation of energy regulations is the strategy most often used by governments to improve the energy efficiency of buildings. Based on Brazilian government incentives initiated in 2001 with Law 10.295, which regulates the National Policy for Conservation and Rational Use of Energy, Brazil has begun to develop methodologies for evaluating the energy efficiency of buildings. In February 2009 the Brazilian Energy Labeling Schemes for Commercial, Public and Services Buildings (RTQ-C) was published followed by the Brazilian Energy Labeling Schemes for Residential Buildings (RTQ-R) in November 2010. This article presents the methodology adopted by RTQ-R, the primary focus of which is the evaluation of naturally ventilated buildings, bioclimatic strategies for encouraging natural ventilation and daylighting, and evaluation of the water heating system. It also presents a review of House Energy Rating Schemes and shows the difference between the Brazilian Scheme and those applied by other countries. These differences are discussed and assessed herein.

This paper addresses the viability of converting single-family residential buildings in Brazil into zero energy buildings (ZEBs). The European Union and the United States aim ZEBs implementation to address ‘peak oil’ and environmental concerns. However, literature shows no agreement on a consensual definition of ZEB. Seeking a Brazilian ZEB definition, this paper addresses PassivHaus and thermal comfort standards for hot climates, source metrics for ZEB, Brazil′s energy mix, residential energy end uses and Brazilian legal framework for residential photovoltaic (PV) generation. Internal Rate of Return for PV systems in two Brazilian cities is calculated under various scenarios. It shows grid parity was reached from April 2012 to November 2012 assuming residential electric tariffs of that period and the financial conditions given by the Brazilian government for the construction of new dams in the Amazon and the lowest rates offered by Brazilian banks to private individuals. Governmental decision to lower electric residential tariffs in November 2012 reduced the scope of grid parity. Later revocation of a tax exemption in April 2013 ended grid parity in Brazil. It concludes, conversely to developed countries, it is the volatile Brazilian energy policy, instead of economical barriers, the main obstacle for ZEB viability in Brazil.

The energy consumption of buildings is an area of increasing importance, and developing economies like Brazil must start to consider the energy performance of existing buildings. The publication of national energy benchmarks is a fundamental step for understanding energy consumption in commercial buildings and developing energy efficiency programmes. A voluntary data gathering initiative by the Brazilian Sustainable Construction Council (CBCS) is producing the data necessary to develop national benchmarks. A methodology for benchmark development is proposed, using both statistical data and energy audit data to benchmark end-use energy consumption, with the use of wet-bulb cooling degree hours for climate correction. Benchmarks and climate corrections are developed for the energy consumption of bank branches in Brazil. A simple linear regression analysis of data from 1890 bank branches in 57 different climates provides the energy consumption benchmark, while thermal simulation of building performance is used to validate the results and provide an end-use breakdown in the different climates studied. This work provides the foundation for further work to develop and publish national benchmarks in other typologies.