Search

Abstract This work assesses the electricity consumption profile of domestic solar hot water systems (DSHWS) and analyses, at high measurement-time resolutions for the first time, their economic viability in popular housing projects in Brazil. It analyses the impacts of the active power demand measurement-time resolution on the financial attractiveness of DSHWS. The predominance of a late-evening profile of electricity consumption for showering, coinciding with distribution utilities' peak demand hours, leads to over 40% avoided active power during peak hours per consumer unit when adopting DSHWS. There is potential to finance DSHWS in popular housing with very favourable conditions for the distribution utility. For discount rates ranging from 0 to 9.5%, payback times ranged between less than four and five years, NPV between $ 2,191 and $ 782, and IRR between 25% and 14%. The measurement of power demand at 15-min intervals, widely adopted by distribution utilities, is not adequate to properly evaluate the financial attractiveness of DSHWS, resulting in pessimistic financial analyses of the return on investment. The low load-factor of electric showerheads used in >90% of Brazilian households, leads to the accounting of only 37% of the real avoided cost of adopting DSHWS when measuring power demand in 15-min intervals. Highlights • Demand measurement time resolution has strong impact on the economics of DSHWS. • Benefits of DSHWS cannot be fully assessed at 15-min measurement-time resolution. • 15-min measurement-time resolution leads to accounting of <40% of DSHWS benefits. • Only 1-min measurement-time resolution reveals full benefits of solar water heating. • Subsidised tariffs for low-income dwellings make DSHWS attractive to the utility. [ABSTRACT FROM AUTHOR]

This work presents a method to evaluate, from the distribution utility's perspective, the impacts of adopting Domestic Solar Water Heating (DSWH) systems in Brazil, based on demand measurements carried out on two groups of residential households. For the 12 months period evaluated, the case-study shows that using DSWH results in savings of 198 kWh (38%), and active power demand savings at peak times of 860 W (42%) per individual unit. For the distribution utility and per individual unit, using DSWH leads to avoided costs of $ 27.59 (38%), avoided costs due to peak time demand reduction of $ 170.2 (42%), and annual avoided costs of $ 197.79 (41%). This work clearly shows that in the residential section the tariff model and structure is strongly distorted, since it only accounts for the energy consumption per residential unit, and completely disregards the costs associated with power demand availability. Our results show that in Brazil the distribution utility charges only some 15% of the real cost of a hot shower based on electric showerheads. [ABSTRACT FROM AUTHOR]

The electrical resistance showerhead is the water heating technology used in over 70% of the Brazilian dwellings. These high power (5–8 kW are typical) instant heating devices contribute significantly to the demand peak in the early evening, and are a major burden to distribution utilities in Brazil. The objective of this paper is to define consumer showering patterns, and analyze the influence of the power demand measurement time resolution on the potential of peak time power demand reduction provided by Domestic Solar Hot Water (DSHW) systems. Results show that the measurement of electrical power demand in a 15-min interval is not adequate to evaluate and verify the benefits provided by the use of DSHW systems, because it heavily underestimates the active power demand reduction at peak hours. This work suggests that a 1-min time resolution can be considered appropriate to assess the potential impacts caused by the use of DSHW systems on the peak hours demand reduction. [ABSTRACT FROM AUTHOR]

The Brazilian territory is irradiated with solar energy ranging from 1500 to 2300 kWh/m 2 /year, compared to 900 to 1850 kWh/m 2 /year in Germany, France, Italy and Spain. Despite that, photovoltaic (PV) technology is only now starting to penetrate the Brazilian electricity mix. Until recently, the high costs of PV generation had prevented this technology from competing in Brazil. However, the consistent PV price reductions and the worldwide scale reached, has brought attention to the Brazilian planners and actions have been taken recently in Brazil to help PV start its progress. In this paper, two of the recent government actions are analyzed, namely the National Electrical Energy Agency ANEEL Resolution RN482/2012, and the announcement of support by the Brazilian Development Bank offering loans at low interest rates for solar PV projects. The effects of these actions for residential PV systems are positive where the conventional electricity tariff is high with respect to the average in the country, and less relevant elsewhere. We compare these tariffs with the calculated Levelized Cost of Energy of rooftop PV generation. The influence of these policies on the return on investment of residential rooftop PV generation is studied for different climatic zones in Brazil. [ABSTRACT FROM AUTHOR]

Abstract: Photovoltaic (PV) generation depends directly on the amount of radiation received by solar modules at a given temperature, and annual irradiation varies according to site location and PV array position. In this paper, the limitations and the solar irradiation levels received by building surfaces in different positions (with azimuth and tilt angle variation) in capital cities in Brazil are shown, making use of the Brazilian global horizontal solar irradiation data provided by the SWERA (Solar and Wind Energy Resource Assessment) project. These data were processed to generate figures on the irradiation at various PV module orientations and slopes for each city, which show the relative radiation levels received on specific azimuth and tilt angles in relation to the ideal position. Results were validated using four real and operating PV systems. In general, variations in azimuth or slope did not cause large annual irradiation losses up to around 20° tilt angles. This shows to PV system planners that under these fairly flexible conditions it is possible to install PV on any orientation, keeping high levels of annual irradiation, and that limitations in orientation and tilt can be relatively low. It also allows a quick analysis of PV retrofit in building-applied photovoltaics (BAPV), when seeking the best building surfaces to incorporate PV. [Copyright &y& Elsevier]

Abstract: Domestic solar hot water systems (DSHWS) have been used worldwide for many decades. Activities in this area are usually targeting middle- or upper-class residential dwellings, and solar collector design and sizing is carried out aiming at this market. In developing countries of the sunbelt, however, there is a huge potential for low-cost DSHWS in low-income residential dwellings. We have assessed the technical and economic viability of this technology, both from the electric utility''s perspective, and from the standpoint of low-income residential consumers. We have analysed data of 12 months of continuous monitoring of a statistically representative sample of consumers at a low-income residential building in Florianopolis – Brazil (27°S, 1550 kWh/m2/year solar irradiation average). We have studied the power consumption of 60 residential units equipped with a commercially available, low-cost DSHWS, and a 30 units control group, where hot water was supplied with the electronic showerhead typical of Brazilian dwellings. Annual electricity savings averaged 38%, and peak-time electricity demand was reduced by 42%. For discount rates of up to 9.5%, this technology is attractive from a utility''s perspective for large-scale deployment. The financial benefit from avoided CO2 emissions has limited economic attractiveness, and can only be justified under a large-scale deployment program. [Copyright &y& Elsevier]

Abstract: Vehicle-to-grid (V2G) energy transfer in a smart grid environment opens a new revenue opportunity for electric-drive vehicles (EVs), and might reduce grid operation costs in demand-constrained urban feeders where peak-electricity prices are high. This paper analyses the peak demand energy market for V2G in the urban region of Florianópolis, Brazil. The article describes known V2G-concepts and introduces two different dispatch strategies developed for the Brazilian energy market in the light of new tariff regulations, which are expected to go into effect starting in 2014. It turns out that electric-drive vehicles may be used as a grid-stabilisation strategy, but the announced tariff regulations may lead to a destabilisation if there are too many cars offering their internal storage for V2G grid support. Adequate energy policy strategies must be introduced to avoid the conflicting interests that might stem from the different perspectives of grid operators and EV owners. In contrast to previous analyses, this research assumes the battery degradation as a function of depth of discharge (DOD), which is known for a specific battery. [Copyright &y& Elsevier]

With the declining costs of photovoltaics (PV), a recent and widespread uptake of residential rooftop PV is underway in Brazil and many other sunbelt countries. Electricity consumers produce some or all their energy and become prosumers = producers + consumers. We present a method to evaluate the role and benefits of residential rooftop PV to prosumers and show a case-study using one of the 1250 PV-powered households in the "Celesc PV Bonus Project", promoted by the local distribution utility Celesc to demonstrate our method in Florianópolis-Brazil. The methodology was divided into five principal stages: (i) Solar resource at the site; (ii) PV system performance indicators; (iii) Consumption profiles; (iv) CO 2 emissions avoided and; (v) Comparative analysis between the individual PV rooftop case study with the average of PV households in the Florianópolis region. From the utility's perspective, the annual electricity consumption was reduced by 18% after PV integration. From the prosumer's perspective, the total annual consumption increased by 8%. However, the annual reduction in electrical utility expenses was 54%. The adoption of rooftop PV in residential households in Brazil was demonstrated to be advantageous, and payback times are still on a downward trend due to the continuing price reductions experienced by the PV technology. • Legislation and declining costs led to a widespread adoption of rooftop PV in Brazil • 1250 identical rooftop PV systems were installed by local distribution utility • Annual electricity bill was reduced by over 50% • As conventional energy prices are increasing, payback times will further decline • Instantaneous self-consumption of PV generation was below 20% [ABSTRACT FROM AUTHOR]

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. • c-Si modules revealed intense degradation in areas with high humidity and temperature. • Thin-film technologies presented a superior performance for most regions in Brazil. • Overirradiance led to blowing of string fuses when maximum fuse ratings were observed. • Optimum time resolution for irradiance data averaging is 1 min. [ABSTRACT FROM AUTHOR]

With the substantial growth of solar photovoltaic installations worldwide, forecasting irradiance becomes a critical step in providing a reliable integration of solar electricity into electric power grids. In Singapore, the number of PV installation has increased with a growth rate of 70% over the past 6 years. Within the next decade, solar power could represent up to 20% of the instant power generation. Challenges for PV grid integration in Singapore arise from the high variability in cloud movements and irradiance patterns due to the tropical climate. For a thorough analysis and modeling of the impact of an increasing share of variable PV power on the electric power system, it is indispensable (i) to have an accurate conversion model from irradiance to solar power generation, and (ii) to carry out irradiance forecasting on various time scales. In this work, we demonstrate how common assumptions and simplifications in PV power conversion methods negatively affect the output estimates of PV systems power in a tropical and densely-built environment such as in Singapore. In the second part, we propose and test a novel hybrid model for short-term irradiance forecasting for short-term intervals. The hybrid model outperforms the persistence forecast and other common statistical methods. [ABSTRACT FROM AUTHOR]

Anthropogenic haze, caused at least in parts by forest and agricultural land clearing fires in Sumatra (Indonesia), is occasionally causing air quality issues in Singapore, located 150–300 km east of the majority of these “hot spots”. The resulting air pollution partially blocks sunlight from reaching the ground, and consequently affects the electric power generation of solar photovoltaic (PV) systems in Singapore. In this work, a methodology is presented to estimate the haze-induced reduction of the light intensity reaching PV panels and the corresponding loss in the electric energy yield. An assessment of a major haze event in June 2013 is the basis for the loss analysis, which takes into account data filtering techniques in order to isolate cloudless conditions for inter-comparison between clear and hazy days. Data from previous years in non-hazy conditions serve as baseline for the determination of the clear sky conditions for Singapore. The novel method is further applied to investigate the power output of ten PV systems in Singapore during the June 2013 haze event. It is found that poor air quality levels during this event caused yield losses of PV systems in Singapore in the range of 15–25%. [ABSTRACT FROM AUTHOR]