Self-consumption Of Electricity Research Articles

Economic and environmental performances of organic photovoltaics with battery storage for residential self-consumption

Recent economic developments have signalled that self-consumption of photovoltaics (PV)-generated electricity could be financially more attractive than exporting it to the grid in many countries. As an emerging PV technology, organic photovoltaics (OPV) have been recognized as potential bearer of economic and environmental gains. Yet, could OPV deliver a profitable investment and environmental impact reductions in the context of residential electricity self-consumption? Here, we conduct a study of unprecedented scoping that combines both economic analysis and life cycle assessment to gauge OPV self-consumption with or without battery storage for household settings. The upscaling of OPV technologies from pilot- to industrial scale was modelled, and we used the two contrasting cases of Denmark and Greece to identify potential patterns. Our economic results indicate that the addition of battery storage is not financially viable unless battery costs are reduced by more than 10% for Greece and 30% for Denmark. Furthermore, we identify OPV cost thresholds of 0.9 €/Wp for Denmark and 1.6 €/Wp for Greece, below which OPV-battery systems are more cost-effective than OPV systems without battery. Building on the economic analysis, we find that battery storage can improve the environmental performances of OPV systems under certain conditions on the battery costs, the capacity of the cost-optimal OPV-battery system, and the environmental impacts of the battery. Furthermore, the composition of the electricity grid mix in the country studied was found to be an important factor to determine where OPV self-consumption was environmentally beneficial. These findings can support energy policy-makers in their development of energy strategies as well as OPV technology developers, who should adopt a systemic approach and integrate battery storage and the balance of system within their development phases.

Self-consumption and self-sufficiency for household solar producers when introducing an electric vehicle

The aim of this study was to analyse how electric vehicles (EVs) affect the levels of electricity self-consumption and self-sufficiency in households that have in-house electricity generation from solar photovoltaics (PV). A model of the household electricity system was developed, in which real-time measurements of household electricity consumption and vehicle driving, together with modelled PV generation were used as inputs. The results show that using an EV for storage of in-house-generated PV electricity has the potential to achieve the same levels of self-consumption and self-sufficiency for households as could be obtained using a stationary battery. As an example, the level of self-sufficiency (21.4%) obtained for the households, with a median installed PV capacity of 8.7 kWp, was the same with an EV as with a stationary battery with a median capacity of 2.9 kWh. However, substantial variations (up to 50% points) were noted between households, primarily reflecting driving profiles.

Transforming a residential building cluster into electricity prosumers in Sweden: Optimal design of a coupled PV-heat pump-thermal storage-electric vehicle system

Smart grid is triggering the transformation of traditional electricity consumers into electricity prosumers. This paper reports a case study of transforming an existing residential cluster in Sweden into electricity prosumers. The main energy concepts include (1) click-and-go photovoltaics (PV) panels for building integration, (2) centralized exhaust air heat pump, (3) thermal energy storage for storing excess PV electricity by using heat pump, and (4) PV electricity sharing within the building cluster for thermal/electrical demand (including electric vehicles load) on a direct-current micro grid. For the coupled PV-heat pump-thermal storage-electric vehicle system, a fitness function based on genetic algorithm is established to optimize the capacity and positions of PV modules at cluster level, with the purpose of maximizing the self-consumed electricity under a non-negative net present value during the economic lifetime. Different techno-economic key performance indicators, including the optimal PV capacity, self-sufficiency, self-consumption and levelized cost of electricity, are analysed under impacts of thermal storage integration, electric vehicle penetration and electricity sharing possibility. Results indicate that the coupled system can effectively improve the district-level PV electricity self-consumption rate to about 77% in the baseline case. The research results reveal how electric vehicle penetrations, thermal storage, and energy sharing affect PV system sizing/positions and the performance indicators, and thus help promote the PV deployment. This study also demonstrates the feasibility for transferring the existing Swedish building clusters into smart electricity prosumers with higher self-consumption and energy efficiency and more intelligence, which benefits achieving the ‘32% share of renewable energy source’ target in EU by 2030.

Impact of electrical vehicle (EV) penetration on the cost-optimal building integrated photovoltaics (BIPV) at a small residential district in Sweden

Buildings are transforming into prosumers because of the intensive growth in photovoltaics (PV), electric vehicles (EV) and home batteries. To adapt such transformation trend, this paper optimizes the cost-optimal capacity and positions of building integrated photovoltaics (BIPV) in a small residential district in Sweden, by considering thermal-electricity loads, power sharing among neighbour buildings, and electrical storage. This study focuses on two optimization scenarios with two different objectives: (1) maximizing net present value (NPV) of the BIPV system, and (2) achieving 27% renewable energy sources (RES) (as set by EU Framework for climate and energy).The optimization is performed with varying penetration of EV demand. The results show that: in scenario (1) the increase in EVs enables larger BIPV capacity with slightly improved self-consumption and thus with a little more profit. In scenario (2) however the levelized cost of electricity (LCOE) of the self-consumed electricity sensibly increases with growing presence of EVs, leading to the decreased profit. In conclusion, three main factors were found that are negatively affecting the performance of BIPV in relation to the EVs in the Swedish residential sector: A low electricity price in summer, a prevalence of the EV load at night, and the absence of PV over-production in winter.

Contribution of Smart Cities to the Energy Sustainability of the Binomial between City and Country

Cities are at the center of the transition to a decarbonized economy. The high consumption of electricity in these urban areas causes them to be the main focus of greenhouse gas emissions. However, they have a high margin of capacity to increase energy efficiency and local energy generation. Along these lines, the smart urban management model has been proposed as a solution to the unsustainability of cities. Due to the global trend of population concentration in urban areas, cities tend to be representative of the population, energy consumption, and energy sustainability of their countries. Based on this hypothesis, this paper studied the relationship between the smart city model and the concept of energy sustainability. First, the research analyzed the relationship between urban population growth and energy sustainability; and then the self-consumption capacity of photovoltaic electricity of the main cities of the countries classified in the energy sustainability indicator (Energy Trilemma Index 2017) of the World Energy Council was analyzed. According to the results, the scope of action for self-consumption of photovoltaic electricity is broad and cities have the capacity to contribute significantly to the energy sustainability of their countries. Following the approach of other authors, the development of energy sustainability objectives and the installation of smart systems in distribution grids must be aligned with national objectives.

Achieving energy resilience through smart storage of solar electricity at dwelling and community level

This paper empirically evaluates the extent of energy resilience achieved in a socially-deprived community in Oxford, through deployment of solar photovoltaic (PV) systems and smart batteries (internet enabled and controllable) across a cluster of 82 dwellings (households). The methodological approach comprised dwelling and household surveys, along with high frequency monitoring of household electricity consumption, solar PV generation, battery charge and discharge data. In the monitored households, average daily electricity consumption was found to be positively related with dwelling size, number of occupants and number of appliances used. Although 117 MWh of PV electricity was generated within a year across 74 dwellings, peak generation did not match peak consumption, demonstrating the need for battery storage. Home batteries were found to increase self-consumption of PV electricity and offset grid demand through discharge of stored PV electricity marginally at an average of 6%, depending on the size of the PV system, surplus PV electricity available and size of the battery. Aggregating solar generation and storage at a community level showed that peak grid electricity demand between 17:00 and 19:00 was reduced by 8% through the use of smart batteries across 74 dwellings. In future, a local energy sharing scheme could be developed, wherein not all dwellings would need to have solar PV systems, but rather have internet enabled batteries that could be monitored and controlled virtually.

Interactive energetic, environmental and economic analysis of renewable hybrid energy system

One of the commitments of the European community is to increase the share of energy produced from renewable sources in order to minimize costs and risks, or that the society has to bear to produce electricity, in addition to compliance with European pollutant gas (CO2, SO2, NOx and PM) objectives. An ever-increasing body of research aims to study the actual energy savings of buildings with systems of renewable energy production implemented with storage systems, evaluating the potential energy savings. To date, however, the analysis of the environmental impacts of the total life cycle was not taken into account. Thus, no assessment has been made whether the amount of energy saved (esaved) outweighs the energy needed for production, use and disposal (einvested). This study presents an approach for the analysis and evaluation of the energy flows, environmental impacts and cost of a new modular and integrated system of renewable electricity generation and intelligent electrochemical storage systems, that allows auto-production and self-consumption of electricity in residential buildings (smart grid). The results show that the total impact depends on the configuration chosen, from the consumption profile and the types of users. If the duration of use is short and the savings achieved are small, the expected benefits will not always be achieved, in terms of costs for the user and the environmental impact.

The economics of solar PV self-consumption in Thailand

Declining prices of solar photovoltaic modules and consumers' interest in green electricity production are driving the prevalence of electricity “prosumers” worldwide. Prosumers are electricity consumers who produce electricity for their own consumption, using distributed energy technologies including distributed solar photovoltaics (DPVs). Many jurisdictions around the world are adjusting to this changing energy landscape by reforming their policies to support self-production and self-consumption of electricity. This paper analyzes the economics of electricity self-consumption of DPV electricity in Thailand. Based on our study, we assess the feasibility of DPV self-consumption schemes for four customer groups. Among the three schemes assessed, (no compensation for excess electricity, net metering, and net billing), all customer classes are profitable and net metering offers the most customer benefits. However, we recommend net billing for policy adoption, not only because of its sufficient level of economic viability but also its flexibility in addressing broad stakeholders' concerns. Our analytical approach captures in detail how DPV sizing relative to the load may be impacted by those compensation mechanisms. Our methodology can be replicated by countries that would like to develop or reform their national-level DPV self-consumption policies during an energy transition.

Complete Procedure for the Economic, Financial and Cost-Competitiveness of Photovoltaic Systems with Self-Consumption

Nowadays, the integration of photovoltaic (PV) systems into the grid involves new and competitive ways to realize this. Thus, it is necessary to define procedures that not only include energy calculations but also incorporate economic and funding feasibility features. According to the literature review, there are numerous tools that are available to carry out a profitability analysis of a photovoltaic system. However, certain shortcomings have been identified, either in the definition of the economic and financial scenarios or in the results obtained, as they do not provide all the necessary information, do not use all the most common economic criteria, or in some cases the complexity and training requirements for their correct implementation may discourage their use. Therefore, in this paper a complete procedure that can be used as a preliminary decision tool prior to the design of an in-depth PV self-consumption system is proposed. Realistic input data makes it possible to not only obtain results for common economic and financial feasibility criteria (Net Present Value, Internal Rate of Return, Discounted Pay-Back Time and Net Cash Balance), but it also allow for a cost-competitiveness evaluation based on the Levelised Cost of Electricity (LCOE). The novel concept of the direct cost of PV self-consumed electricity is also introduced.

Prosumers in the Electricity System—Household vs. System Optimization of the Operation of Residential Photovoltaic Battery Systems

An increase in distributed small-scale generation and storage in residential prosumer households requires an understanding of how the household-controlled operation of these distributed technologies differ from a system-optimal utilization. This paper aims at investigating how residential photovoltaic (PV)-battery systems are operated, given different assumed incentives, and whether or not a prosumer induced operational pattern differs from what is desirable from a total electricity system point of view. The work combines a household optimization model that minimizes the annual household electricity bill for two price zones in southern Sweden with a dispatch model for the northern European electricity supply system. The results show significant differences in the charging and discharging patterns of residential batteries. A household annual electricity cost minimization gives many hours in which only a fraction of the battery capacity is used for charging and discharging, mainly driven by incentives to maximize self-consumption of PV-generated electricity. In contrast, in a total electricity system operational cost minimization larger fractions of the available battery capacity are utilized within single hours. In the total system optimization case, the batteries are charged and discharged less frequently and the energy turnover in the batteries is only half that of the household optimization case. For all the cases studied, the hourly electricity price provides only a limited incentive for households to operate their batteries in a system-optimal manner.

太陽光発電余剰電力の宅内自家消費に関する研究 （その3）エコキュート昼間運転と蓄電池の組合せ手法による評価および予報値の精度検証

太陽光発電余剰電力の宅内自家消費に関する研究 （その3）エコキュート昼間運転と蓄電池の組合せ手法による評価および予報値の精度検証

Sociodynamic modeling of small-scale PV adoption and insights on future expansion without feed-in tariffs

Understanding complex phenomena such as energy transitions, which bear technical, economic and social dimensions, requires a multi-directional approach. Expansion of the solar energy in the energy mix of a country is similarly complex, as its decentralized nature brings about a necessity of public approval and trust besides its economics. We therefore develop a combined socio-economic model, which is based on the sociodynamics framework, for the household-level adoption of photovoltaics (PV). We apply the model to the cases of German and Italian PV expansion and make a retrospective analysis regarding their dynamics, in order to identify the importance of various factors such as the profitability and the public opinion throughout their expansion timeline. We then project our model for the German PV expansion onto the near future and investigate the requirement of feed-in tariffs to maintain the expansion targets under various scenarios. Results of our projection point at the importance of the self-consumption of PV electricity; an average self-consumption ratio higher than 25% makes a phase-out of feed-in tariffs by 2030 possible, whereas 50% self consumption renders the feed-in tariff regulation obsolete even in today's economic conditions.

Demand aggregation for photovoltaic self-consumption

The mismatch between photovoltaic generation and residential load leads to relative modest rates of self-consumption of solar electricity unless expensive storage solutions are locally available. One alternative to batteries is the aggregation of demand of different prosumers, as the collective load diagram might be better adapted to the solar resource. This hypothesis is tested for empirical data from 18 dwellings and 3 small businesses in the city of Lisbon, Portugal. Results show that a relatively low number of dwellings and a local small shop with a PV system without any storage will reach 90% self-consumption rates at a much lower cost than an individually owned PV system with 1 kWh/kWp storage system. • Real demand data for residential dwellings and small business. • Prosumer aggregation more efficient than battery. • Aggregation of 10 households has significant impact on self-consumption rates. • Aggregation of different demand profiles is very effective.

The impacts of photovoltaic electricity self-consumption on value transfers between private and public stakeholders in France

Between 2016 and 2017, the French Government made significant advances in shaping the new legislative structure in order to support photovoltaic electricity self-consumption, which is a growing challenge for many countries developing renewables close to the grid parity. By analyzing all the main financial flows linked to the electric bill, the sales of electricity and the investment in photovoltaic systems, this study aims to identify the stakeholders that benefit or suffer the most from value transfers caused by photovoltaic electricity self-consumption compared to full injection. The results suggest a shortfall of revenue for the distribution system operator. An increase in the electric bill of other grid customers will undoubtedly offset this shortfall. Simultaneously, the French State would make savings for individual self-consumption projects below 100 kWp. The new policy also incentivizes the self-consumption for big consumers for whom it is more profitable and competitive. Self-consumption projects tend to be economically more attractive than projects in full injection when the photovoltaic system is not oversized for the electric demand. The policy may consequently imply risks for the equalization of electric grid charges among consumers, the sustainability of the current business strategy of utilities and the security of supply.

Impact of consumption profile discontinuities on the feasibility of a PV plant

The revenues of a grid-connected photovoltaic plant are strongly related to the local climatic conditions. In addition, since self-consumed electricity is much more valuable than that traded with the main power grid, also consumption profile plays a key role in the profitability of a PV system. Self-consumption to total PV production ratio depends on the temporal mismatch between energy generation and demand. The amount of energy that is not self-consumed may be very high in the case of a consumption profile with several discontinuities. This study is focused on the analysis of a grid-connected PV system serving a compressed natural gas (CNG) fueling station. These facilities are energy-intensive users, characterized by high variability of electricity demand due to intermittent operation of gas compressors: in a few seconds the total load may change from 100% to 5% and vice versa very frequently during the day. The analysis was based on data acquired on the field for the compression station and those already present in the literature for solar irradiation. The influence on plant design of the time step used for the analysis was studied in detail. The outcomes showed that the typical and well-assessed design approaches of a PV pant may lead to errors when used for the design of systems with several consumption profile discontinuities.

On the competitiveness of grid-tied residential photovoltaic generation systems in Pakistan: Panacea or paradox?

Pakistan is experiencing a slow uptake of grid-tied residential PV generation Systems (GTRPVGS); despite of steep fall in PV module price, higher solar irradiation and enactment of Net-metering by the Government. This slow uptake is attributed to the lack of awareness of four major stakeholders, namely the house hold, utility, financier and the policy-maker. This paper presents a coherent framework that addresses the concerns of the stakeholders using four country-specific parameters i.e. the local solar irradiation, PV system costs, borrowing and discount rates, and electricity tariffs; to compute NPV, IRR, payback period and levelized cost of electricity (LCOE). Assuming net-metering, we model the economic payoffs on self-consumption and sale of PV electricity at varying net-metering rates, system sizes, load-to-generation profiles, borrowing and discount rates. Findings suggest economic competitiveness of PV electricity, with an IRR and payback averaging around 28% and 5 years respectively. Moreover, the LCOE is also found to be significantly lower than the retail rates. The findings inform the household and financier on the economic yield; utility on efficient tariff setting; and government on sustainable policy design. Finally, we argue that GTRPVGS bears huge potential for Pakistan, suffering from energy deficit, unsustainable cost, transmission losses and environmental hazards.

A hybrid renewable system based on wind and solar energy coupled with an electrical storage: Dynamic simulation and economic assessment

This work presents a thermo-economic simulation model of a hybrid renewable power plant based on wind turbine and photovoltaic technologies, coupled to an energy storage system. The total plant capacity is 200 kW (190 kW and 10 kW, for photovoltaic and wind turbine, respectively), whereas the energy storage capacity is 400 kWh. Aim of this work is to design a renewable power plant showing limited fluctuations (with respect to the ones typically achieved in case of solar systems) with marginal amounts of electricity purchased or sold to the grid, maximizing the electricity self-consumption. The thermo-economic model, developed in TRNSYS environment, allows one to determine the best system configuration and maximize the economic profitability by considering the time-dependent tariffs applied to the electricity exchanged with the grid and the possibility to store electricity. Different system layouts with or without the storage system and for different users are considered. Results show negative profit indexes of the layouts including the storage system (−0.27 in the worst case vs. 0.61 in the best case without the storage), due to its lower efficiency and its higher capital cost, although a remarkable reduction of the operating costs and an enhancing of the self-consumed energy.

Sharing electricity storage at the community level: An empirical analysis of potential business models and barriers

More and more households are installing residential electricity storage systems to increase the self-consumption of electricity they produced. Some governments have accelerated this development through specific financial support schemes to offset the costs, which still remain high. Compared to the use of single-household systems, the sharing of mid-scale electricity storage systems in neighborhoods could reduce the Levelized Costs of Storage (LCOS). However, a model for the shared usage of storage by multiple households has yet to emerge. We investigated eight demonstration projects in Germany and Western Australia with capacities between 100 and 1100 kW h with respect to potential business models and barriers in a cross-case study based on document analyses and expert interviews. We found that models relying on the transmission of electricity from individual rooftop photovoltaics to a shared storage system through the public grid are facing significant regulatory barriers. Removing these policy barriers would enable a more efficient use of electricity storage systems. By contrast, projects relying on a less regulated microgrid managed by the administration or strata entities of multi-household developments already seem promising under the current regulatory framework.

Cost-Effectiveness of Li-Ion Battery Storage with a Special Focus on Photovoltaic Systems in Private Households

Using a self-developed economic model with a technical battery aging component, this paper provides a new approach to evaluating the economic efficiency of Li-ion battery storage. We use our model to quantify the increase in self-consumption of electricity from a solar photovoltaic system by means of a home battery storage system. Regarding battery aging, we find that the longest battery lifetimes can be achieved with the highest state-of-charge limit, which is, however, not economically efficient due to limited self-consumption. Although one of the three battery pooling concepts was identified as not being economically efficient, namely the case of Sonnen, our evaluation shows that economic efficiency can, in principle, be achieved with home battery pooling concepts. In future research, the model-based impacts on self-consumption and battery-aging found here ought to be validated by using real world data from the systems analyzed.

Performance of a photovoltaic plus battery home system with load profile scenarios changing over the system life

The ratio of self-consumed electricity to total electricity produced by a photovoltaic (PV) system depends on whether consumption and production match in time. A temporal mismatch can be partially overcome by buffering the energy produced by PV, e. g. in a battery. A key impact factor which affects the techno-economic performance of PV-battery systems is the household load profile, which may significantly change over the lifetime of the PV-battery system, but the effects of a changing load profile on e. g. the self-consumption ratio were not yet investigated. This paper shows on three different examples the possible changes over the 21 year lifetime of a typical PV-battery system. It is demonstrated that changes in the behavior patterns and the number of residents can cause the self-consumption to vary by more than a factor of 2 over the lifetime of the system. When dimensioning such a system e. g. for optimal return on investment over the lifetime or for a certain degree of autarky, not only changing energy prices, but also changing household structure and changing behavior of the household members should be taken into account.