Joint study by EUPD Research and Anker SOLIX shows: Storage solutions significantly increase the economic efficiency of balcony power plants

21/04/2025|Anker

Abstract

Market breakthrough for storage solutions in plug-in PV systems: 90 per cent of storage systems are installed directly | Cost savings through self-consumption optimisation: up to 64 per cent lower electricity costs, amortisation from four years | Data-based usage analysis: annual savings of up to EUR 373, 50 per cent more self-consumption through storage | Trend towards more powerful systems: increasing demand for larger PV and storage solutions in urban areas.

Berlin, 18.04.2025 / Decentralised energy generation is becoming increasingly important in Germany. Small solar systems for balconies are in vogue - and with the right storage system, they can also become more and more economically relevant for users. This is shown by a recent market study by EUPD Research, a leading market research institute in the field of renewable energies, in collaboration with Anker SOLIX, a leading innovator in the field of solar energy storage solutions.

The study analyses the economic viability of plug-in PV systems with storage and shows how consumers can significantly reduce their electricity costs. Market data, political framework conditions and real consumption and installation patterns were analysed - supplemented by concrete calculation scenarios for three typical household profiles.

Storage solutions on the rise: 90 per cent of new storage systems are installed directly

According to EUPD Research, around 222,000 battery storage systems were installed in conjunction with plug-in PV systems in Germany in 2024 - an increase of 97 per cent compared to the previous year. The majority of these systems (around 90 per cent) were installed together with new PV systems and not retrofitted. This shows that storage systems are no longer an optional accessory, but are increasingly being recognised as an integral part of balcony solar systems.

At the same time, the average system size for plug-in PV has also increased - from 0.8 kWp in 2023 to 0.91 kWp in 2024. The study anticipates further market expansion in 2025: around 675,000 new plug-in PV systems are expected to be added, which corresponds to a total installed capacity of around 635 MW. This trend is also reflected in the growing share of plug-in systems in the total installed capacity in the residential building sector - from 3 per cent (2023) to an expected 8.2 per cent (2025).

Cost-effectiveness: Storage increases self-consumption and significantly reduces electricity costs

Using three sample calculations with households with annual consumption of 1,000, 3,000 and 4,500 kWh, the study analyses the cost-effectiveness of different system sizes. The scenario for a medium-sized household is particularly convincing: A system with 2,000 Wp of PV power and 2 kWh of battery storage reduces electricity costs by 64 per cent and therefore pays for itself in around four years.

Even smaller setups, for example 1,000 Wp PV + 1 kWh storage, lead to noticeable savings. In a single-person household with an annual consumption of 1,000 kWh, electricity consumption from the grid can be reduced by around 45 per cent, with a payback period of five years. This shows that even with moderate consumption, storage systems can make economic sense if self-consumption is optimised.

Anker SOLIX data confirms: 50 percent more self-consumption, up to EUR 373 savings per year

To validate economic efficiency, Anker SOLIX evaluated its own anonymised usage data. The analysis is based on the period from August 2024 to March 2025 and relates to several thousand Solarbank user households in Germany. The results prove it:

Average self-consumption increases by more than 50 per cent with battery storage.
A typical configuration with 4 modules and 3.2 kWh of storage achieves an average annual saving of EUR 373.
The average amortisation period is 5.4 years.
In individual cases, for example, with favourable orientation, high usage and low basic consumption, annual savings of over EUR 900 were achieved.

Interest is growing despite economic barriers to entry and regulatory uncertainties

At the same time, the study shows that many consumers are actively looking for self-sufficiency solutions and are prepared to implement them themselves: Around 50 per cent of storage solutions are retrofitted by consumers themselves or installed directly as DIY systems. Nevertheless, the high purchase price of storage systems remains a key obstacle according to the survey: 68 per cent cite this as the main hurdle, while 73 per cent generally do not (yet) consider storage systems to be economically attractive. In addition, only around 27 per cent of storage systems are located on balconies - i.e. where plug-in PV is particularly obvious. The rest are mainly installed in garages (25 per cent) or on the roofs of residential buildings (24 per cent).

In addition, there are regulatory uncertainties, for example with regard to registration or the technical design of storage solutions in combination with existing PV systems. The lack of standardisation in subsidy programmes at municipal or state level also makes the investment decision difficult for many interested households. In addition, tenant households often do not have access to traditional solar subsidies, although there is considerable potential for plug-in solutions, particularly in urban apartment blocks.

This discrepancy between technological potential and perceived cost-effectiveness emphasises the need for better funding instruments, more transparency about real savings and easily accessible solutions, especially for tenant households, which are often excluded from traditional solar subsidies.

Outlook for the future: Plug-in storage as part of the decentralised energy transition

The results of the EUPD study make it clear that plug-in PV systems with storage are not a niche phenomenon. They are establishing themselves as a mainstay of the decentralised energy supply. A shift towards larger PV and storage solutions is to be expected in the coming years, as the demands on households are increasing. According to the Anker SOLIX utilisation trends considered in the study, developments can be seen in the following areas:

The proportion of larger systems (such as configurations with more than 3 kWh of storage) is increasing.

The demand for PV systems with four or more modules is growing.

At the same time, interest in higher AC output power is increasing in order to also serve devices with constant power requirements.

Currently, the legally permissible inverter power for plug-in systems in Germany is 800 W, which already enables a significant reduction in grid consumption for many standard household applications. Nevertheless, an internal analysis by Anker SOLIX shows that systems with an output power of up to 5,000 W have the potential to cover almost the entire daily demand of an average household with an annual consumption of 4,500 kWh - especially with optimised alignment and storage management.

This prospect is supported by scenarios in the EUPD study, in which households with higher consumption (e.g. 3,000 or 4,500 kWh per year) can expect a self-consumption rate of up to 91 per cent, provided a sufficiently large storage system is available.

At the same time, these scenarios show that feeding surplus energy into the grid at high consumption levels is hardly economically viable, as self-consumption remains more lucrative in most cases than remuneration under the Renewable Energy Sources Act.