Benefit evaluation of PV orientation for individual residential consumers

Photovoltaic (PV) installations located in the northern hemisphere must be oriented to the south in order to obtain maximal annual yield. This is mainly driven by the remuneration mechanisms which incentivize maximal energy production to a certain extent. Nowadays, such support mechanisms are declining or even phased out in many countries. Hence, self-consuming the produced energy is getting more viable. In order to match better the load demand pattern, the azimuth angle of a PV installation could be changed or oriented towards multiple directions. This article investigates the benefits of PV installations facing other directions than the south. Therefore, the Hay & Davies transposition model has been used to calculate the in-plane irradiance, as it is found in the literature to be the most accurate for non-south faced PV installations. In order to determine the benefit, a large dataset of real measured consumption profiles has been used and then divided according to their annual consumption. Large consumers with an oversized east/west-oriented PV installation especially take advantage. The self-sufficiency index (SSI) is found to increase with almost 0.94 percent points, while the self-consumption index (SCI) increases with 6.46 percent points. The peak reduction is assessed by calculating the annual moving average of the month peaks. It is found that this moving average month peak reduction is marginal. Lastly, the reduction in storage capacity is found to be not that significant, although in terms of battery utilization it is found that the number of discharge cycles is reduced with 6%

A low-voltage DC backbone with aggregated RES and BESS : benefits compared to a traditional low-voltage AC system

The increasing penetration of PV into the distribution grid leads to congestion, causing detrimental power quality issues. Moreover, the multiple small photovoltaic (PV) systems and battery energy storage systems (BESSs) result in increasing conversion losses. A low-voltage DC (LVDC) backbone to interconnect these assets would decrease the conversion losses and is a promising solution for a more optimal integration of PV systems. The multiple small PV systems can be replaced by shared assets with large common PV installations and a large BESS. Sharing renewable energy and aggregation are activities that are stimulated by the European Commission and lead to a substantial benefit in terms of self-consumption index (SCI) and self-sufficiency index (SSI). In this study, the benefit of an LVDC backbone is investigated compared to using a low-voltage AC (LVAC) system. It is found that the cable losses increase by 0.9 percent points and the conversion losses decrease by 12 percent points compared to the traditional low-voltage AC (LVAC) system. The SCI increases by 2 percent points and the SSI increases by 6 percent points compared to using an LVAC system with shared meter. It is shown that an LVDC backbone is only beneficial with a PV penetration level of 65% and that the BESS can be reduced by 22% for the same SSI

A novel feature set for low-voltage consumers, based on the temporal dependence of consumption and peak demands

This paper proposes a novel feature construction methodology aiming at both clustering yearly load profiles of low-voltage consumers, as well as investigating the stochastic nature of their peak demands. These load profiles describe the electricity consumption over a one-year period, allowing the study of seasonal dependence. The clustering of load curves has been extensively studied in literature, where clustering of daily or weekly load curves based on temporal features has received the most research attention. The proposed feature construction aims at generating a new set of variables that can be used in machine learning applications, stepping away from traditional, high dimensional, chronological feature sets. This paper presents a novel feature set based on two types of features: respectively the consumption time window on a daily and weekly basis, and the time of occurrence of peak demands. An analytic expression for the load duration curve is validated and leveraged in order to define the the region that has to be considered as peak demand region. The clustering results using the proposed set of features on a dataset of measured Flemish consumers at 15-min resolution are evaluated and interpreted, where special attention is given to the stochastic nature of the peak demands

Peak demand dynamics of low-voltage consumers under aggregation and its impact on upstream PV injection

Renewable Energy Communities will allow consumers on the low-voltage grid to actively participate in the energy market. This work explores the dynamics of the daily peak demands of these communities under aggregation, as multiple countries are introducing capacity-based grid tariffs for residential consumers. Both the aggregation level and yearly consumption of the households comprising it are shown to have a significant impact on the timing of the daily peak demands. While considering both the size of the PV installation and its orientation as variables, it is subsequently shown that this effect of the aggregation level is extended to the PV self-consumption and self-sufficiency indices

RE/SOURCED pilot project : design and power flow analysis of a LVDC backbone with hybrid energy system

The European Commission introduced recently the new concept of energy communities which are aiming at accelerating the energy transition. RE/SOURCED, which stands for Renewable Energy SOlutions for URban communities based on Circular Economy policies and Dc backbones, is a project that aims at implementing a renewable energy community at the former power plant site in Belgium. One of the novel aspects of the project is the interconnection of the different energy storage systems and renewable energy sources by means of a LVDC backbone. In this paper, a power flow analysis of the LVDC backbone is performed in order to determine the appropriate cable size. Based on this analyses the energy losses are computed for a LVDC backbone architecture. Subsequently, the benefit in terms of energy savings, self-consumption and self-sufficiency is investigated compared to the traditional grid architecture

Reducing the residential PV-BESS size by means of an LVDC backbone : impact on voltage unbalance and energy efficiency

A hybrid AC/DC grid, segregating the demand on the existing AC grid and the renewable production and storage on an LVDC backbone responds to the challenges faced nowadays when integrating DER on the traditional AC grid. The single point of injection by means of an LVDC backbone has a number of advantages, which are assessed in this study. Having an unbalanced AC grid with PV and storage increases the benefit of an LVDC backbone. This leads to significant savings in PV and storage, a reduction of the voltage unbalance and an improvement of the energy efficiency

Self-sufficiency and lifetime improvement of community BESS on an LVDC backbone compared to individual BESS

Previous analyses on the benefits of LVDC backbones have exposed the huge potential in urban environment with high PV penetration. However, the energy efficiency and lifetime improvement by integrating a community battery energy storage systems (BESS) on an LVDC backbone have not been thoroughly investigated yet. In this contribution multiple comparisons are made between individual and virtual community BESS on LVAC and real community BESS on LVDC. It has been shown that the reduced conversion loss and the slight lifetime improvement are the main advantages of community BESS on LVDC compared to individual BESS on LVAC

Dynamic voltage control strategy for increasing the efficiency of an LVDC backbone with BESS and converter-less PV integration

An LVDC backbone with aggregated PV and BESS is a promising grid architecture leading to a considerable reduction of the energy losses. Additionally, previous analysis showed that the replacement of the multiple small DC/AC inverters in a traditional LVAC grid by one central DC/AC inverter creates many other scale-related advantages. The operating voltage level is an important parameter therein as it has a direct impact on the cable and conversion losses. As the PV and BESS voltages and powers exhibits a high variability due to the natural intermittency of solar irradiance, potential benefits emerge when a dynamic backbone voltage optimisation is applied instead of a static voltage. Moreover, by extending the objective of the optimisation with the maximisation of the produced PV power, the DC/DC converter, which guarantees the maximum power point (MPP) operation of the PV system, could be eliminated. The dynamic voltage strategy will hence be driven by a multi-objective optimisation algorithm in order to define the Pareto front between minimising the cable and conversion losses and maximising the PV yield. The elimination of the DC/DC converters would lead to a reduction of the cost, the space and the complexity of the installation. The obtained results exhibits a clear decrease of 53% in energy losses when applying a dynamic voltage strategy with MPP tracker (MPPT). This is mainly caused by the decrease in cable losses and conversion losses in the second stage DC/DC of the central grid inverter. Eliminating the MPPT leads to a slight increase of the losses which is a consequence of the compromise between the predefined objectives. However, this slight loss increase combined with the 1% curtailment loss opens perspectives to simplify the PV installation and to reduce the balance of system cost

Impact Assessment of Electric Vehicle Charging in an AC and DC Microgrid: A Comparative Study

This paper presents an in-depth comparison of the benefits and limitations of using a low-voltage DC (LVDC) microgrid versus an AC microgrid with regard to the integration of low-carbon technologies. To this end, a novel approach for charging electric vehicles (EVs) on low-voltage distribution networks by utilizing an LVDC backbone is discussed. The global aim of the conducted study is to investigate the overall energy losses as well as voltage stability problems on DC and AC microgrids. Both architectures are assessed and compared to each other by performing a power flow analysis. Along this line, an actual low-voltage distribution network with various penetration levels of EVs, combined with photovoltaic (PV) systems and battery energy storage systems is considered. Obtained results indicate significant power quality improvements in voltage imbalances and conversion losses thanks to the proposed backbone. Moreover, the study concludes with a discussion of the impact level of EVs and PVs penetration degrees on energy efficiency, besides charging power levels’ impact on local self-consumption reduction of the studied system. The outcomes of the study can provide extensive insights for hybrid microgrid and EV charging infrastructure designers in a holistic manner in all aspects.</jats:p

Dynamic Voltage Control Strategy for Increasing the Efficiency of an LVDC Backbone With BESS and Converter-Less PV Integration

An LVDC backbone with aggregated PV and BESS is a promising grid architecture leading to a considerable reduction of the energy losses. Additionally, previous analysis showed that the replacement of the multiple small DC/AC inverters in a traditional LVAC grid by one central DC/AC inverter creates many other scale-related advantages. The operating voltage level is an important parameter therein as it has a direct impact on the cable and conversion losses. As the PV and BESS voltages and powers exhibits a high variability due to the natural intermittency of solar irradiance, potential benefits emerge when a dynamic backbone voltage optimisation is applied instead of a static voltage. Moreover, by extending the objective of the optimization with the maximization of the produced PV power, the DC/DC converter —which guarantees the maximum power point (MPP) operation of the PV system —, could be eliminated. The dynamic voltage strategy will hence be driven by a multi-objective optimization algorithm in order to define the Pareto front between minimizing the cable and conversion losses and maximizing the PV yield. The elimination of the DC/DC converters would lead to a reduction of the cost, the space and the complexity of the installation. The obtained results exhibits a clear decrease of 53% in energy losses when applying a dynamic voltage strategy with MPP tracker (MPPT). This is mainly caused by the decrease in cable losses and conversion losses in the second stage DC/DC of the central grid inverter. Eliminating the MPPT leads to a slight increase of the losses which is a consequence of the compromise between the predefined objectives. However, this slight loss increase combined with the 1% curtailment loss opens perspectives to simplify the PV installation and to reduce the balance of system cost