In recent years, the research interest in bidirectional charging of electric vehicles has increased significantly, driven by improved accessibility to charging and payment information as well as the increasing emphasis on integrating variable renewable energy sources more effectively into the grid. Integrating bidirectional charging with the grid/building/home can also reduce grid congestion. Despite this, broader implementation of this technology has not yet been achieved. In this context, this article comprehensively surveys direct current (DC) off-board vehicle to grid/building/home chargers and analyses the gaps which prevent the technologies’ wide implementation. These gaps are analysed by considering areas such as the development direction of bidirectional charging technology, battery cost and its degradation, V2G applicable standards, grid codes and charging protocols, deployment of V2G chargers (off-board versus on-board/wireless), market feasibility of V2G services, and the cost of bidirectional off-board chargers. The first survey of twenty-five commercial bidirectional chargers is presented and investigated in relation to the above-mentioned areas. Four key (technical, regulatory, financial, and behavioural) barriers are identified and discussed for the wide implementation of vehicle to grid/building/home charging.

Electric vehicles (EVs) with vehicle-integrated photovoltaics (VIPV) and vehicle-to-grid (V2G) technology can help address power grid challenges arising from the energy transition. While VIPV and V2G offer widespread benefits, their impact on EV battery life affects their economic viability. Many existing studies examining the impact of VIPV and V2G on EV battery life do not fully capture the complexity of real-world battery usage, often relying on less detailed battery data. This work models and combines detailed and validated EV battery data with validated battery ageing models to determine the impact of VIPV and V2G on EV battery life. First, a validated EV battery simulation model is used to generate realistic, per-second battery data for an EV operating in The Netherlands and Spain. Following this, VIPV power profiles, V2G day-ahead energy trading power profiles, and V2G automatic frequency restoration reserve power profiles are integrated with the battery data. Subsequently, battery datasets for different scenarios are implemented in both NMC and LFP-based semi-empirical ageing models to quantify calendar and cycling ageing capacity loss. The results show that gradual VIPV charging decreases the required annual grid charging frequency by 23% in The Netherlands and 44% in Spain, leading to lower SoC ranges, which can reduce NMC and LFP calendar ageing capacity loss by 9% in both countries. Additional cycling due to V2G day-ahead energy trading can shorten battery life by up to 12.5 years for NMC and up to 3.9 years for LFP. Moreover, the research indicates that ageing models based on tests with regular power profiles may not accurately estimate cycling ageing in power profiles with increased irregularity caused by VIPV and V2G.

Vehicle-to-Everything (V2X) is a promising solution to support the energy transition, but concerns about battery degradation and capacity loss remain a major barrier for electric vehicle (EV) users. A clear understanding of degradation caused by V2X is essential to increase user confidence and encourage participation in V2X services. Many V2X studies have researched battery degradation, but the results vary widely between articles, making it hard to draw conclusions. Existing review articles mention the different outcomes but do not discuss the contradictions. In this article, a large set of V2X degradation studies is compared using a quantitative analysis. The yearly added degradation due to V2X is extracted from 37 V2X degradation papers, resulting in a set of 97 data points. The dataset is analysed to compare degradation in different situations and highlight contradictions in similar situations. Results show that the average yearly added degradation is 0.87% (95% CI: 0.35–1.4%). When degradation is explicitly considered in V2X service optimisation, the added degradation is limited to just 0.9% per year. Moreover, under specific conditions, V2X can even help reduce overall battery degradation by reducing calendar ageing. Temperature and SoC are especially important in assessing the benefit of V2X on calendar ageing, but these factors are most often overlooked. This review has highlighted common shortcomings in V2X degradation literature that affect the assessment of the impact of degradation. The results can be used to clear up misconceptions about degradation in V2X and to guide future research directions.

In low-voltage distribution networks, the high penetration of renewable energy generators in residential buildings has proven challenging for system operators. In response, the grid operators can reinforce the grid infrastructure or deploy battery energy storage systems throughout the network to compensate for the voltage fluctuations. Alternatively, new energy markets for ancillary services have been proposed to involve the prosumers; however, most are at medium and high voltage levels. This paper investigates, from a cost perspective, what conditions can make it attractive for individual prosumers to participate in a low-voltage ancillary service market, specifically power curtailment and peak shaving. We considered a prosumer with a 2 kWp PV system for both ancillary services, adding a 10 kWh battery for the peak shaving case. Curtailing power to comply with the maximum power exchange with the grid does not create any significant change in the LCoE of the PV system, keeping it near 0.072 €/kWh for permitted return grid powers above 1.25 kW. Scenarios closer to zero-injection increase exponentially the LCoE to 0.222 €/kWh. Using a semi-empirical ageing model, we estimated the degradation of the batteries for the cases with and without providing peak shaving, concluding that doing peak-shaving to avoid demanding more than 1 kW from the grid extends the battery life by up to 320 % while increasing its LCoS only 9.5 % when compared to a zero-consumption scenario due to the reduced depth-of-discharge and number of cycles. The results suggest that power curtailment and peak shaving can be attractive for prosumers, thus creating opportunities for ancillary services business models at the residential scale.