Entering its tenth year, the photovoltaic magazine Deutschland once again conducted a market overview of residential battery energy storage products. As the world's leading distributed storage market, Germany's technology and application trends, including the shift to electric vehicle charging integration, are inspiring for global market participants. Interestingly, the price decline is still slow.
Suppliers are seeking to achieve single-phase charging at higher power levels, because single-phase grid connections have power limitations depending on the country/region. SMA's electric car charger was launched in November last year, which can charge single-phase with a power of 7.4 kilowatts by combining the grid and solar energy.
Although there have been signs of market consolidation in the residential storage sector in recent years, 120 new systems have been added to the 2021 Photovoltaic Magazine's residential battery storage market overview, many of which are from new suppliers. In addition, according to the supplier, 74 systems have undergone major revisions or updates.
In the 2021 survey, a total of 45 suppliers provided detailed information on 408 systems. Two are wholesalers, while the others are system integrators and manufacturers. Some provide integrated systems, while others focus on inverters or battery modules for storage systems. The results summary table was published in the June edition of the photovoltaic magazine Deutschland (German), and the complete database can be accessed through the German photovoltaic magazine website. It includes technical details of more than 100 feature system entries.
There is a big difference in the products surveyed. Therefore, it is not surprising that in a corresponding survey of 139 German installers, 60% believed that there was a significant difference between the brands, and these companies represented a total of about 27,500 home storage systems installed in the country.
The most relevant to installers is their own experience of system quality. In the past, many installers had to bear some expenses when suppliers updated products to fix errors. Now 46% of home storage products in our database allow automatic remote updates, thereby reducing the installer’s responsibility for door-to-door maintenance or renovation. But this means that 54% of the surveyed systems do not yet have such labor-saving features.
In the scores considered relevant by the installer, quality and warranty are directly followed by the point interface. The storage system database shows the main differences between the systems. For example, 139 of these products allow the heating system to be controlled to increase self-consumption. Among them, 96 products can clearly control the heat pump through the SG-Ready interface, while 129 products provide at least one other interface. For example, SMA and Viessmann use EEBus, and Sonnen uses KNX. E3/DC, Enphase, Fenecon, ASD and Fronius provide communication via Modbus, usually using Sunspec standards. Senec, RCT, Kostal and Growatt use switchable contacts. Only 51 products allow direct control of the power consumption of the heat pump, which can achieve a higher self-consumption increase compared to using the SG-ready interface. However, in larger-sized solar and storage systems, this advantage will diminish.
Interfaces also play a role in one of the most important new trends that manufacturers and installers must deal with-electric vehicles. A recent survey of about 500 installers in a photovoltaic magazine webinar found that in Germany, a large proportion of consumers have already taken electric vehicles into consideration when planning solar + energy storage systems, even if they do not already own them. electric car.
One of the triggers for the sudden rise in interest in charging solutions is the German electric vehicle charging subsidy program KfW program. The program provides subsidies of up to 900 euros for residential electric vehicle charging stations, provided that they use renewable electricity to charge electric vehicles. If the charging power can be controlled according to the availability of excess solar power from the roof system, the proportion of solar energy used in the car and the "self-consumption" rate of the photovoltaic system can be increased. The crux of storage customers lies in the compatibility of electric car chargers with different household energy management systems, as well as the interface of smart meters.
According to the 2021 survey, many manufacturers have responded to consumer demand for electric vehicle charging integration, because 151 of the 408 systems can be combined with electric vehicle chargers that can be controlled in a solar-optimized manner. Many allow communication with commonly used electric car charging brands in Germany.
For example, Solarwatt batteries are compatible with Keba and Webasto EV chargers. Other products, such as those provided by Fronius, use commercial products such as Go-e and adjust them according to their system requirements. The Fronius system has a special feature, it can use variable electricity prices through the internal products Lumina and Awattar. Consumer electricity prices vary according to the electricity exchange prices. If there is not enough solar energy, the car will be charged from the grid, but only if the electricity price is below an adjustable threshold. Application controls can align electric vehicle charging with solar surplus, variable electricity prices, or the requirements of the owner's plan for the next leg of the journey.
Another function that needs attention in the controller is phase switching. In countries/regions where households use three-phase grid connections, such as Germany, three-phase electric vehicle chargers allow higher charging power, but the disadvantage is that they are not allowed to be charged with a power lower than 4 kW. In order to fully charge the excess photovoltaic power, not only on sunny days with high photovoltaic power generation, automatic phase switching places the charging power on a single phase. This allows it to be reduced to 1.38 kW.
Other suppliers are looking for solutions to achieve single-phase charging at higher power levels than the unbalanced load conditions of the grid connection allow. For example, the SMA EV Charger launched in November last year can also perform single-phase charging with a power of 7.4 kW by combining the grid and solar energy.
The charging and discharging rates of residential batteries are also evolving. These rates are becoming more and more important due to the requirements of power-consuming loads such as electric vehicles or heat pumps. Among the battery systems under investigation, the smallest charging power is ET Energies Tiny 3.5, which is only 0.8 kW. The highest charging capacity is the Pacdu Container with three modules, reaching 120 kW, so it is more likely to be used in commercial applications. E3/DC is introducing a system with an output of 30 kW to the German market.
Looking at the survey results, about three-quarters of the systems are in the usual range between 2 kW and 10 kW. Slightly more than half of the batteries in the survey have a capacity that can be modularly expanded. These modules are usually small, ranging from 1.44 kWh to approximately 6 kWh. However, some companies also offer larger modules, such as myzun with 9 kWh modules, BYD Battery-Box Premium LVL with 15.4 kWh, or Powertrust Crystaltower with up to 22 kWh.
Seven suppliers-namely Energy Depot Swiss, ET Solar Power, Fenecon, myzun, neoom, Pro Rogenic Energien, and Solarax-provided the market overview with publicly released information on suggested retail prices (excluding installation). Prices are not always directly comparable. For example, myzun only sets prices for batteries, while the integrated Sunsilo system also includes a hybrid inverter. Therefore, the range of functions provided by the battery is different, which complicates direct comparison. In addition, some systems provide emergency power or even full backup power, while other systems do not.
Twelve suppliers only provide prices on a confidential basis. In addition, the German team from Photovoltaic Magazine conducted an independent market survey on prices. Based on all available data, a picture as realistic as possible is constructed, so that the "storage power cost" of various complete systems can be calculated.
In this case, dealing with the energy management system is also somewhat difficult. For example, energy management is often included when purchasing storage systems. However, some photovoltaic systems without storage also provide energy management. Therefore, the cost of the energy management system is not included in the storage cost calculation. In fact, the cost of an energy management system can vary greatly, depending on the scope of functions, from simple electric energy meters to complex self-learning systems.
In order to establish a better comparability between AC and DC systems, the cost of the assumed solar inverter was subtracted when calculating the cost of the integrated DC coupling system and the system including the hybrid inverter.
The calculated cost of stored electricity is the cost of storing 1 kWh of electricity first, and then discharging the battery in a way that runs optimally. The cost of stored electricity is calculated relative to the warranty life of the system, assuming 300 cycles per year. Considering the huge difference between German winter and summer irradiation, this is already an optimistic assumption for the self-use operation of German photovoltaic arrays . nation. In fact, the acquisition cost must usually be amortized over fewer cycles, and the actual cost of storage and discharge per kilowatt-hour is higher.
Most of the products in the survey, 78%, have a 10-year warranty. Only four manufacturers provide it for less than 10 years, and two provide it for 15 years. Six manufacturers guarantee that the production capacity will be less than 80% at the end of the warranty period, 30 adhere to the 80% standard, and 2 even guarantee 100%. For 59% of products, the manufacturer will provide a time value replacement service in the event of a warranty claim. For 26% of the systems, 11 manufacturers even provided a complete replacement.
In our 186 quotations, the average cost of storing electricity from a kWh battery is 0.38 Euro/kWh-until the end of the warranty period, including 19% VAT. Compared with last year's survey, this price dropped by 2 cents. The minimum cost is 0.17 Euro/kWh, which is two cents higher than the 2020 survey.
Some manufacturers also guarantee the capacity of the battery within a certain number of cycles. Calculating the energy turnover rate based on the guarantee period usually results in lower prices for stored electricity. For a system that guarantees 12,000 cycles, the minimum cost is 0.09 Euro/kWh.
When the planned application requires more than one cycle per day, more cycles become relevant-if the battery is to provide grid service functions, this is conceivable. For example, the German Energy Storage Systems Association (BVES) wants to activate Germany’s 2.3 GWh of residential energy storage capacity and is trying to remove regulatory barriers to make it easier for customers to enter these energy markets.
However, so far, 66% of the respondents in the PV Magazine installer survey believe that electricity services, clouds, or community models are not important or unimportant. But if BVES succeeds, this situation may change quickly. Therefore, for customers and manufacturers, the ability to modify different functions and allow openness for future development will remain an important issue.
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