Bidirectional charging – possibilities, risks and opportunities

published on 17th February 2022, updated on 16th ​May 2022

E-mobility is gaining ground in Germany. After the number of vehicles with electric motors (incl. plug-in hybrids) registered to drive on German streets reached the one-million mark in July last year, this trend has sped up again: Since then, over 230,000 further electric vehicles have been registered with Kraftfahr-Bundesamt (German Federal Motor Transport Authority), of which around 62 % were fully electric. Also noteworthy is the rapid increase in registered electric vehicles over time since 2016, as Figure 1 shows. After almost quadrupling from 2019 to 2020, this number is again expected to increase by around 70% year-on-year in 2021.

   Fig. 1: Number of registered vehicles in Germany between 2016 and 2021 by type of motor (as of: 30/11/2021).

Note: BEV – battery-electric vehicle.

In-house study based on data from Kraftfahrt-Bundesamt (Kraftfahrt-Bundesamt - Umwelt (kba.de)).

In perspective, however, we are only at the very beginning of a trend: According to the new coalition agreement of the Social Democrats (SPD), the Greens and the Free Democrats (FDP), the number of registered fully electric passenger cars is to multiply to at least 15 million by 2030. Given the development of final energy consumption in the area of renewable energies in the transport sector on the one hand¹ and the covenanted greenhouse gas emission reductions on the other², a huge transformation in the transport sector is also urgently needed. If this target is actually achieved, in less than nine years there will be 15 million mobile battery storage units in German driveways, car parks and company car parks for most of the day – up to 23 hours a day according to the "Mobility in Germany” study.³ The battery capacity of the new vehicles registered to drive on German roads in 2020 already totals around 9 million kWh.⁴ Assuming that the average battery capacity remains at the same level during this decade, over 700 GWh, or over 700 million kWh, would already be temporarily stored in electric vehicles in 2030. This amount of energy could theoretically cover Germany's average electricity demand for around 11 hours.

Short-term and long-duration storage technologies

In order to estimate storage demand for Germany with an increasing penetration of renewables in the electricity mix, it is useful to distinguish between short-term and long-duration energy storage. The Federal Ministry for Economic Affairs and Climate Action describes short-term storage facilities as storage facilities

•  with a high power to capacity ratio (kW to KWh),
• which run through several cycles per day,
• which are used for short-term fluctuations or for load balancing/shifting during a day
• and are technically mostly batteries and pumped storage units. Long-duration storage, on the other hand, is a long-term storage option
• for prolonged idle times, as a back-up or for seasonal storage,
• which run only through a few cycles per year
• and are technically either power-to-x (typically hydrogen and methane), and large pumped storage power plants.

Consequently, the batteries of electric vehicles should clearly be regarded as short-term storage units.

For an electricity system with a 80 % share of renewables in Germany, which is the declared goal of the new federal government to be achieved by 2030, the German Association for Electrical, Electronic & Information Technologies (VDE), for example, estimates that demand for short-term storage will be at 70 Gwh and for long-duration storage at 7.5 TWh, in addition to existing pumped storage. For a scenario where renewables have a 100 % share, increased demand for short-term storage of 184 GWh is estimated, and that for long-duration storage rises to 26 TWh. A study by the Fraunhofer Institute ISE estimates that short-term storage demand will be 112 GWh for the 100% share-of-renewables scenario with more than threefold demand for long-duration storage capacities.⁵ As can be seen in Figure 1, 10-15 % and thus only a fraction of the potentially available e-mobility capacity would be needed to meet demand for short-term storage in the 80 % share-of-renewables scenario.

   Fig. 2: Demand for short-term storage and e-mobility in 2030.

As regards predicting the mobility behaviour in Germany and thus the availability of electric vehicles, the above-mentioned study by BMVI also provides valuable insights for this: for example, on a representative day, 41% of passenger cars were standing unused in private households. In addition, about one fourth of passenger cars’ mileage in Germany is attributable to daily commute to work, which makes the vehicles potentially useful for load management measures, as long as the employer provides the necessary equipment in the workplace.⁶ Given the coronavirus pandemic and the transition to remote work, the above-mentioned values should rather be understood as the lower limit. In consequence, supply of available cars exceeds demand many times, assuming that adequate charging infrastructure is provided.

The dimension of the potential storage capacity of electric vehicles is impressively illustrated from another perspective: There are currently 6.2 GW of pumped storage systems installed in Germany, which fed 7 TWh into the German electrical grid in 2020.⁷ Assuming that electric vehicles or their batteries have a capacity of 3.7 kW⁸, then the total of electric vehicles registered in Germany in 2030 will have a capacity of 55.5 GW. Given that the necessary 10-15% of electric vehicles are available as shown in Figure 1, 5.55 to 8.33 GW of power would then still be available, which thus would be more than the total of the pumped storage systems installed in Germany. It is crucial that this capacity is made usable for the whole energy system, and ideas should be explored how to further embrace that potential and the impact. 

Fig. 3: Installed capacity of short-term storage systems – a comparison between electric vehicles and pumped storage plants

Bidirectional charging concept and business models

The concept of discharging power from the battery of the electric vehicle to put it back to the grid as part of smart load management when the EV is not used is not new and is called bidirectional charging. It is divided into discharging to participate in intraday trading (base-peak spread trade), vehicle-to-grid (V2G) and vehicle-to-home (V2H), with each of these options serving different interests and thus addressing different market players.

Both V2G and base-peak spread trading require smart and secure IT communication and close networking, so that information about available vehicles, the (planned) use of the electric vehicle by the customer and the power that can be taken from the car battery and pushed back into the grid in a certain period of time can be determined promptly and without much effort. Likewise fundamental is the use of a common communication standard or the interoperability of different systems so that a costly duplication of structures can be avoided.

Vehicle-to-Grid (V2G)

V2G focuses on the electric vehicle as an option to stabilise grid. If there are deviations between the forecast and actual generation, the grid operator needs to have balancing energy very quickly at hand in order to compensate for fluctuations in the grid frequency and thus to ensure grid stability. The idea behind V2G is that energy from the vehicle battery is supplied to the grid operator for this purpose. Consequently, the potential of electric vehicles in supplying balancing energy is already being investigated by a working group of the German transmission grid operators. Through the weekly auctions for primary balancing energy and the daily auctions for secondary balancing energy and minute reserve power, V2G can also generate revenue for the vehicle owners and the service provider. The revenue that can be generated is not negligible: With the increasing penetration of renewables in the electricity mix and with no adequate storage options, the electricity mix will become significantly more volatile, which will increase the need for balancing power. 2 December 2020 is a perfect example for this: due to a power plant failure, transmission system operators had to call up positive secondary balancing energy in the amount of 1,300 MWh, for which up to 63,000 €/MWh was paid. Fortunately, this is not the rule and revenue opportunities remain well below this, but this example illustrates the potential.

 The Munich-based electric vehicle maker Sono Motors, for example, developed a bidirectional wallbox for its electric vehicle, the Sion, together with the German company Kostal, in order to be able to charge and discharge it at 11 KW.[1] Via a dedicated app, owners can specify whether and to what battery charge level they want to discharge their car. Crucial is here the interface to the Home Energy Management System (HEMS). A recommendation as to which HEMSs can communicate with the wallbox is to be made close to the date of the Sion's launch in 2023.

The city of Utrecht in the Netherlands, which has pre-ordered 100 Sions, has already announced its intention to enter the balancing market and thus contribute to a stable supply of power to the grid. In principle, this business model is also very attractive to German companies such as car-sharing providers, as the trend is increasingly shifting towards a "sharing economy" where the user of a thing acquires the right to use it for a certain period of time, but does not own it at any time. In addition to the added value created for the grid, this opens up a second line of business for the participating companies that does not require additional hardware – a win-win for everyone involved! The same applies to all medium-sized companies that use larger vehicle fleets, e.g. on weekdays, which are however not used at weekends.

Base-Peak-Spread Trading

The idea behind the base-peak-spread trading is simple: the electric vehicle is charged using the owner's own PV system or when much cheaper renewable electricity is fed into the grid. In times of peak demand and thus higher prices, the energy is discharged from the battery of the electric vehicle to be sold on the electricity market. The difference between the price paid on charging and the generated revenue is the profit margin payable to the vehicle owner less charges to the service provider. In the following sample calculation it is assumed that an electric vehicle charges 30 kWh per 3 ct at night and, because the vehicle owner works in her home office that day, 10 kWh per 9ct can be discharged in the morning and 20 kWh per 10 ct in the evening. Thus, the vehicle owner receives 2.00 euros for that day before deducting the charge to the service provider, which is done entirely automatically by software, while the charge level of her car remains identical.

π=10kWh*0,09€+20kWh*0,1€-30kWh*0,03€=2,00€ (1) 

This seemingly low amount adds up in the course of the year resulting in a significant amount – both for the service provider and for the vehicle owner. If it is assumed that the charge is 25%, the latter can quickly make over 250-300 euros/year out of this. For the service provider, the possible amount per vehicle is correspondingly lower, but the following fundamental fact should be taken into account before calculating his revenue: due to large volumes that are traded on the electricity market, he must combine several electric vehicles into a “virtual power plant” in order to achieve significant power volumes in that way and sell them on the European Energy Exchange (EEX). As a consequence, the revenue of the service provider strongly increases along with the number of electric vehicles available for use. Therefore, this option is again possible and attractive especially to companies with their own large fleets of electric vehicles or to car sharing service providers or to any company that combines the potential of private electric vehicle fleets and thus exploits it.

Thus, the base-peak-spread trading business model is comparable to that of the pumped storage systems – only that electric vehicles focus on mobility and additionally allow achieving revenue through smart charging and discharging. Currently, due to low availability of charging stations and too low capacities of the e-mobility sector, it does not appear to be financially attractive as evidenced by the fact that no service provider is known on the market as of now. However, this will only be a matter of time due to the rapidly increasing market penetration of electric vehicles and the associated technology.

Base-peak spread trading should be distinguished from cost optimisation in the area of private electricity procurement, which is achieved through prices that depend on the time of the day and is offered by some electricity suppliers. The declared aim here is to reduce private electricity bills.⁹

Vehicle-to-Home (V2H)

As opposed to V2G and intra-day trading, V2H does not require any electricity supplier acting as the intermediary. The focus here is on smart load management of the private consumer where the consumer's electric vehicle is used as private energy storage facility and feeds power into the consumer’s house if no production (typically using PV sources) takes place (e.g. at night) or if it is lower than actual consumption. This option is very attractive especially to private consumers with their own PV power plants (the so-called prosumers), because it enables increasing the share of self-consumption and promises a large degree of energy self-sufficiency in summer months – the energy storage facility in a fully charged electric vehicle with average battery capacity and without charging the car in between during the day can theoretically fully supply a household of four for over four days (as long as the vehicle is not used for driving).¹⁰ An energy manager of the vehicle normally already regulates that only excess PV electricity produced will be stored in the vehicle and priority is given to electricity required by household devices. 

The assessment of the impact of V2H on the current business model of utility companies depends on many factors. Among other things, it is important

• whether the private consumer has their own PV power plant on their roof which they can use in the summer months to charge their car (according to the expansion plans of the new federal government, hardly any new building will be built without such a system or any already existing buildings without such a system will be added the charging equipment. Because the on-site tenant electricity supply model [Mieterstrommodell] will be significantly improved, potential considerably increases also in this area);
• how often the vehicle is used for driving and thus cannot be charged given a high level of self-produced energy;
• whether the car can be charged on the employer’s premises.

In the best-case (for the private consumer) scenario where they have their own PV power plant, a (smaller) stationary battery storage and the possibility to charge the electric vehicle on the employer's premises, a very high degree of energy self-sufficiency of up to 100% plus supply of heat through a heating pump can be achieved in the months between spring and fall. Over the course of the year, one- and two-family households can achieve a degree of self-sufficiency of just over 70% in this way, provided that the available roof area is available.¹¹ For a household with annual consumption of 4,000 kWh, the possibility of V2H would mean an increase in self-consumption of several hundred kWh/year compared to the current status, which would have a direct impact on the revenues of electricity distributors. Since over 36% of Germans own a one- or two-family house, which makes the installation of a PV power plant relatively uncomplicated, the loss potential for electricity distributors is immense. In the following example it is assumed that 100% of demand for electricity required by a local municipality (10,000 inhabitants) is purchased from the local electricity supplier, and that all one- and two-family houses are fully modernised in that they purchase a PV system, local electricity storage facility and an electric vehicle with the possibility of bidirectional charging:

In consequence, local electricity distribution companies may lose up to 25% of their revenue compared to a 0% self-sufficiency scenario, if the trend towards decentralised electricity supply and the maximisation of the degree of self-sufficiency under optimal conditions for private end consumers continue to grow.

On the other hand, of course, it can be assumed that total demand for electricity in that municipality is likely to increase due to electric vehicles. According to the BMVI study mentioned above, electric vehicles have a mileage of 13,000 km/year, which is just below the average estimated annual mileage of 14,700 km.¹² If these figures are treated as reference values and average real energy consumption

of 17 to 21 kWh/100 km is assumed, demand for electricity per electric vehicle will be approx. 2,200 kWh to approx. 3,000 kWh per year.

Thus, approximately 1,000 electric vehicles charged only in the municipality where the vehicle owners live would be needed to compensate for the loss on the distribution side of the electricity supplier. Taking into account the rate of homeowners and their partial ability to supply their own electricity, and assuming that demand for electric vehicles was the same in these two groups, approximately 1,330 electric vehicles would be needed within the municipality.

 Fig. 4: Changed demand for electricity in e-mobility taking into account the home ownership rate.

 
Given the approximately 3,600 private vehicles in the exemplary municipality¹³, this would represent a share of fully electric vehicles of 37 % – well above the 31% that should be registered on German roads by 2030 if the transport policy target is met.¹⁴ In other words, the municipality residents' demand for fully electric vehicles would have to be above-average just to compensate for the loss of revenue suffered by the municipal electricity supplier.

Furthermore, the assumption that the vehicle will be charged exclusively within the distribution area of the municipal supplier is highly unrealistic – there is no obvious reason why the vehicle should not be connected to a charging facility on the employer's premises as long as the necessary infrastructure is provided. Moreover, the vehicle is driven for the exact reason of covering longer distances, e. g. to get to the next bigger city, as a result of which the vehicle will probably drive outside the distribution area of the electricity supplier. In this case, the number of electric vehicles needed to compensate for the loss of revenue expected by the electricity supplier in the place of the car owner's residence increases immensely.

Of course, all these calculations should be treated with great caution, as they depend on very many factors that are not taken into account in these calculations. For example, the impact of demographic trends on demand for private cars is essential, as is, for example, the development of self-supply options (including its regulatory framework) such as the on-site tenant electricity supply model [Mieterstrommodell] or the efficiency of electric vehicles. Nevertheless, the calculations show that, in future, electricity suppliers will have to be prepared for a strong change in demand due to sector coupling – and this change will be to their disadvantage, as shown here.

On the other hand, the imminent radical changes in the electricity supply can have upsides even for electricity suppliers: As shown, financial profit opportunities can arise for them when placing energy on the electricity balancing market or through base-peak spread trading, provided that the potential of e-mobility is used. With two-way communication between the vehicle owner and the grid operator, electricity supplier, etc., large amounts of energy can be fed into the grid, thus generating significant revenues for both sides. Here, it is important that the owner is given sufficient incentives to actively participate in scheduling management and, in the best case, to make his car available to the grid operator or the service provider during all hours in which it is not needed. Conceivable is the tried and tested system of a service fee and kilowatt-hour rates: For every hour the car is made available, the vehicle owner receives a small fixed fee. If electricity is discharged back to the grid, the owner additionally receives compensation for every kWh, of which he is informed transparently and promptly. Even if this is still "up in the air", these business models will certainly appear in the markets in the short term – assuming that the regulatory framework is created for this to make the above-mentioned potential usable. This is an essential building block for the success of the energy transition.

Are there hurdles?

Power producers’ liability

But, of course, where there is light, there is also shadow. What is frequently criticised is the performance of the battery, which generally loses capacity more quickly because it goes through a higher number of cycles. However, this is only half the truth, as normally with V2H and V2G the battery does not go through a full discharge cycle, which means that capacity loss is lower. Furthermore, studies to date have not found any significant negative effect of V2G on the life of the electric vehicle. Nevertheless, this needs to be further tested, especially in the context of field tests.

Last but not least, this is also a question of liability: Will producers of electric vehicles continue to give their customers long-term warranty promises regarding the durability of the battery? For Tesla, the matter is currently clear: If the car is used as a temporary electricity storage, the warranty expires. On the other hand, there are many car manufacturers who are actively participating in V2G and V2H pilot projects, such as Renault and Nissan. With a lot of zest and an investment package of over 100 billion euros announced for a comprehensive e-mobility strategy, VW is now also embarking on integrated e-mobility and has announced that the VW ID.5 and ID.5 GTX models delivered in 2022 will already be equipped with a bidirectional charging function. In almost the same breath, it has been announced that "charging and energy are becoming a core business of Volkswagen" in order to be able to offer the advantages of using the electric vehicle as stationary storage for V2X from one source, as highlighted in this article. According to VW, this will not only combat the curtailment of renewable power due to grid congestion, but has also met with widespread interest and thus promises potential for VW, according to a survey among 1000 VW ID drivers. This commitment underlines the attractiveness of the business segment that is emerging due to the rapidly increasing number of electric vehicles in Germany – at the same time, it means that a tycoon of the automotive industry wants to occupy this market, which means that interested companies face tough competition.

The technology

Just like stationary electricity storage, electric vehicles have low losses of 10-15 % due to the transformation of the alternating current from the domestic grid into direct current for use in the battery. Although this is an excellent result, especially in comparison with other storage media such as PtG, not every kWh fed into the grid can be fully taken back from the grid again. Furthermore, having the primary purpose of mobility in mind, it becomes extremely difficult to exactly determine power losses on transformation during charging and discharging, which raises further questions, as in the calculation of compensation rates for V2G.

 Furthermore, the inverter itself plays a decisive role in charging and discharging: If it is installed exclusively in the vehicle and not in the wallbox, it often turns out to be a bottleneck. While an inverter in the wallbox or a public charging station charges the vehicle with direct current and a charging point of 50 kW or more, in the future even up to 350 kW, commercially available wallboxes (for home use) feed alternating current of maximum of 11 kW and provide one charging point of max. 3.7 kW in the case of single-phase chargers. Consequently, the equipment used for charging can significantly reduce the attractiveness of the electric vehicle for V2G purposes. Furthermore, due to their currently low purchase quantities, bidirectional wallboxes are very expensive with their prices ranging from 2,000 to 4,000 euros excluding installation costs (and subsidies) (but this is likely to change considerably in the further roll-out).

 Currently, in technical terms, the crux lies primarily in the IT system, which has to bring together the different interests of the stakeholders. The first systems, e.g. the universal communication standard EEBUS, which is used by the joint research project "Bidirectional Charging Management – BCM", have yet to prove their performance in large-scale applications. Software solutions such as ChargePilot from the technology company Mobility House, which were primarily developed for load management applications in larger vehicle fleets or in the private sector, appear to be more advanced here.

Regulatory framework

The technical difficulties, however, are by far not the biggest obstacles. The current regulatory framework stifles the use of electric vehicles as temporary energy storage units even before it started. In addition to many other reasons, such as data protection regulations, tax issues or possible de minimis criteria, the regulations of the Energy Industry Act (EnWG) and the Electricity Network Charges Regulation (StromNEV), which generally continue to treat electricity storage units as a load at the time of charging and as a generation system at the time of discharging, are a major obstacle.¹⁵

Furthermore, in contrast to private, stationary storage units that are charged with self-generated PV electricity, the batteries of electric vehicles are considered grey electricity generation systems when energy is discharged, which means that the private owner is required to pay the reduced EEG levy if he meets the less strict exemption criteria¹⁶ – this applies even if the electric vehicle was charged exclusively with the owner's self-generated PV electricity, as it is assumed that it is impossible to provide verifiable documentation for this.

It is obvious that the legislator should introduce immense adjustments in many different areas in order to make the potential of sector coupling exploitable. 

Conclusion

 
First of all, it should be emphasised that the potential of e-mobility in Germany as a temporary storage facility is huge. The combination of high performance, high capacity and long service life make electric vehicles very attractive in terms of their multiple use. All in all, this is also a win-win-win:

• vehicle owners can generate revenue by participating in the balancing market or intraday trading;
• grid operators are provided with huge, otherwise largely unlocked potential offered by temporary electricity storage, which reduces the need for fossil-fuelled power plants for peak load energy generation;
• ultimately, the electricity price for all consumers decreases, resulting in lower network charges and enabling consumers to make optimal use of self-generated PV electricity.

The presented technical problems are more an expression of the fact that some components of the system are not yet ready for the market than a question of technical feasibility. Clearly it is the politics that can make the ball spin. Without a fundamental change in the current legal framework, it will not be possible to unlock the above-described potential of e-mobility. At least likewise elementary is the early setting of standards to prevent the inefficient duplication of structures, e.g. in the communication between the wallboxes and the grid operators or the metering technology. In addition, financial support for bidirectional wallboxes should be worth considering so as to prevent a large-scale rollout of unidirectional wallboxes. Furthermore, a look across the English Channel to Great Britain could offer valuable insights, where potential of bidirectional charging for helping ensure electricity grid stability has long been recognised as such.

The cooperation between Mobility House with its in-house software "Marketplace", the car manufacturer Renault and the local energy supplier EEM on the Portuguese Atlantic island of Porto Santo shows how it can be done: Since 2019, a pilot project has been run to test and optimise the synergies between electric vehicles, stationary electricity storage and renewable energy generation plants in order to supply the island with carbon-neutral energy in the long term. Last but not least, VW's recently publicly announced commitment to enter the electricity supply market and sell storage units for (private) load management measures, and thus theoretically also to be able to place them on the balancing market, makes it clear that there are prospects of significant revenues in these areas.

In view of the statements in the coalition agreement of the SPD, the Greens and the FDP that "the cross-sector use of renewable energies [and] decentralised generation models [...] will be consistently [strengthened]" and that an independent legal definition of energy storage systems will be adopted, hopes that the regulatory framework for electric vehicles as temporary electricity storage units will improve soon have not been so high for a long time. This could give a promising, dynamic market the necessary impulse to get off to a flying start and open up new, attractive revenue-making opportunities for all companies that notice the possibilities of bidirectional charging early enough. 
 

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¹ Final energy consumption of renewable energy sources in the mobility sector was 0.5% in 2000 and had successively increased to 7.3% in 2020, mainly due to the requirement to blend biofuels. Electricity from renewable energy sources still contributes less than 1% to total energy consumption in transport. Source: Renewable energies in figures | Umweltbundesamt [Federal Ministry for Economic Affairs and Energy].

² By 2030, emissions from the transport sector should be reduced by 42% compared to 2020, while from 1990 to 2020 they only fell by just under 11%. Source: Less greenhouse gases in transport (bundesregierung.de).

³ Source: infas, DLR and infas 360 (2018): Mobility in Germany, on behalf of the Federal Ministry of Transport and Digital Infrastructure (BMVI).

⁴ Source: “Storage on wheels” from: Energie und Management 6, dated 01/06/2021.
⁵ Möller (2020), as part of her dissertation: Storage requirements and system costs in power supply for energy self-sufficient regions and districts.
⁶ Source: infas, DLR and infas 360 (2018): Mobility in Germany, on behalf of the Federal Ministry of Transport and Digital Infrastructure (BMVI), p. 70-71.
⁷ The Bundesnetzagentur (2021): Monitoring report 2021.
⁸ This should be understood as the lower limit; many electric vehicles have power of 7.4 kW and 11 kW up to 22 kW.

⁹ Electricity suppliers include e.g. aWATTar (https://www.awattar.at/), Tibber (https://tibber.com/de) or STROMDAO with their product Corrently (https://www.corrently.de/home.html).

¹⁰ Assumed average consumption: 4000 kWh/year, which is approx. 11 kWh/day.
¹¹ Kaschub, T., Jochem, P. und Fichtner W. (2016): Solar energy storage in German households: profitability, load changes and flexibility, Energy Policy (98), p. 520-532.
¹² Source: infas, DLR and infas 360 (2018): Mobility in Germany, on behalf of the Federal Ministry of Transport and Digital Infrastructure (BMVI), p. 80.

¹³ See BMVI study, p.35 "Pkw-Besitz nach Haushaltstyp [Car ownership by household type]", which indicates that there is an above-average number of family households that own more than one car.
¹⁴ According to the Federal Motor Transport Authority [Kraftfahrt-Bundesamt, KBA], there were around 48.2 million passenger cars in Germany's total motor vehicle population as of 01/01/2021 (Kraftfahrt-Bundesamt - Bestand (kba.de). Although this figure has been rising for years, the value for 2020 has currently been carried over to 2030. If the vehicle population continued to increase, this percentage share would continue to decline.
¹⁵ EnWG § 3 No. 25 in conjunction with StromNEV § 14 (1), Sentence1, to which the Federal Court of Justice refers in its judgment EnVR 56/08 of 17/11/2009 in the last instance and confirms this.

¹⁶ Since the amendment of EEG 2021, stricter criteria for eligibility for the exemption from the reduced EEG levy for green electricity generated and used by the same person apply at 30 kW and 30 MWh/year, while the limit for grey electricity generation systems remains at 10 kW and 10 MWh/year.

 

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