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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: Inverter sizing strategies for grid-connected photovoltaic (PV) systems often do not take into account site-dependent peculiarities of ambient temperature, inverter operating temperature and solar irradiation distribution characteristics. The operating temperature affects PV modules and inverters in different ways and PV systems will hardly ever have a DC output equal to or above their STC-rated nominal power. Inverters are usually sized with a nominal AC output power some 30% (sometimes even more) below the PV array nominal power. In this paper, we show that this practice might lead to considerable energy losses, especially in the case of PV technologies with high temperature coefficients of power operating at sites with cold climates and of PV technologies with low temperature coefficients of power operating at sites with warm climates and an energy distribution of sunlight shifted to higher irradiation levels. In energy markets where PV kWh’s are paid premium tariffs, like in Germany, energy yield optimization might result in a favorable payback of the extra capital invested in a larger inverter. This paper discusses how the time resolution of solar radiation data influences the correct sizing of PV plants. We demonstrate that using instant (10s) irradiation values instead of average hourly irradiation values leads to considerable differences in optimum inverter sizing. When calculating inverter yearly efficiency values using both, hourly averages and 1-min averages, we can show that with increased time resolution of solar irradiation data there are higher calculated losses due to inverter undersizing. This reveals that hourly averages hide important irradiation peaks that need to be considered. We performed these calculations for data sets from pyranometer readings from Freiburg (48°N, Germany) and Florianopolis (27°S, Brazil) to further show the peculiarities of the site-dependent distribution of irradiation levels and its effects on inverter sizing. [Copyright &y& Elsevier]

An analytical approach to evaluate and to optimize the life cycle savings of hybrid diesel-photovoltaic plants is carried out. The life cycle savings is evaluated, considering one or more diesel generator sets, operating in different fixed power levels, with special attention to the case of high specific fuel cost. The condition under which optimum photovoltaic module area exists is analyzed. In the particular region of the northern part of Brazil, it is shown that there are several favorable conditions to implement photovoltaic generation, in the range of current electricity tariffs and diesel oil costs practiced in the market. [Copyright &y& Elsevier]

• Area-intensive PV power plant topology scenarios were optimized. • Simulation of over 26,700 combinations using a PV system sizing software tool (PVsyst) were carried out. • Area-related utility-scale solar power plant optimization method was developed. • Best topology leads to 12.4% reduction in LCOE, and 91% higher area-related energy yield. This paper deals with the optimization of utility-scale, single-axis tracking PV power plant design, and suggests the use of a new evaluation metric Y AREA , represented by the annual energy yield normalized by the PV power plant area. This metric takes into account both the energy yield (MWh/MWp) and the total energy production efficiency of the PV plant (MWh/m2), performing an optimization of both yield and available area. To illustrate and validate the proposed method, historical solar irradiation data were treated and used as input data for the creation of a large number of PV power plant topology scenarios spread over the Brazilian 8.5 million km2 national territory, and a case study was presented to illustrate the proposed method. The new metric showed important results for the PV plant design decision-making process, indicating a technical optimization complemented by the evaluation of the LCOE, leading to an economic optimization. While the topology defined through Y AREA presents an average of 12.4% reduction of the maximum LCOE found, it presents a 58.9% enhanced Y AREA and 91.4% more energy generated per surface area, almost doubling the investment potential over an area. [ABSTRACT FROM AUTHOR]

• Solar and wind resources have a relevant temporal complementarity in the Brazilian NE. • Energy mix 40% wind and 60% solar requires minimal storage capacity to supply Brazilian NE load. • Role of storage in reducing the transmission infrastructure needs for renewable energy is evaluated. • Storage increases dispatchability of utility-scale wind and solar power plants. • _______________________________________________________________________________________________ Solar and wind sources together provided more than half of the Brazilian Northeast electricity generation in 2019. This growing share of renewable energies in the Brazilian energy matrix increases the importance of portfolio optimization and the energy storage management. This paper assesses the complementary nature between wind and photovoltaic generation in the Brazilian Northeast, and how this complementarity, together with energy storage, can reduce the shortcomings that the corresponding natural resource intermittency imposes on these sources. The work consists of two main analyses: (i) analysis of the capability in supplying the Brazillian Northeast region power demand with a hybrid wind + solar + storage power plant; and (ii) contingency optimization analysis for hybrid wind + solar + storage power plants. The results show that wind and solar resources are consistently complementary in the region, with a daily Pearson's Correlation Coefficient of −0.51. Also, the load supply analysis shows that a renewable energy mix based on a 40% wind and 60% solar share would require the equivalent of only 6% of its annual generation in storage capacity. An energy curtailment analysis showed that the complementary nature of the wind and solar resources, together with energy storage, can lead to a reduction of up to 11% in transmission capacity demand. [ABSTRACT FROM AUTHOR]