Plug-in solar: Solar power from the balcony directly into the socket

Soon simpler rules for plug-in solar devices?

The Association of Electrical Engineering Electronics Information Technology eV (VDE) published a position paper on January 11, 2023 in which it calls for simpler rules for plug-in solar devices. The consumer advice centers welcome the planned simplifications. Currently, these simplifications, including the release of the Schuko plug, the elimination of registration with the network operator and the increase in the power limit from 600 to 800 watts (AC), are only a suggestion in the VDE position paper. They are therefore not yet valid and applicable.

The Federal Association of Consumer Organizations (vzbv) also supports the use of Schuko plugs.

Important to know: Since January 1, 2023, photovoltaic systems and battery storage have been subject to a sales tax rate of 0 percent. This 0 percent also applies to plug-in solar devices.

1. What is a plug-in solar device and how does it work?

Do you have a balcony or terrace? Then you can generate your own solar power there and become an active part of the energy transition - with a plug-in solar device. These small photovoltaic systems are often also called mini solar systems, plug & play solar systems or balcony power plants because they can be mounted on the balcony railing, for example. However, it is not a “system” in the technical sense, but rather a household appliance that generates electricity.

What can a plug-in solar device do?

The solar module generates electricity from sunlight, which an inverter converts into “household electricity”. This is connected directly to an existing circuit in the apartment. In the simplest case, you plug a plug into an existing socket.

For example, the electricity from the plug-in solar device flows into the socket on the balcony and from there to the television, refrigerator and washing machine, which are plugged into other sockets in the apartment. The electricity meter then counts more slowly and less electricity is drawn from the public grid. If the electricity from the balcony is not enough to operate the household appliances, electricity from the utility simply flows in from the grid.

Without a connection to the grid, the solar devices do not produce any electricity. When camping or in the allotment garden, you can instead use so-called “island systems” with a battery and another type of inverter.

Plug-in solar devices usually consist of 1 or 2 standard solar modules and an inverter. Depending on the equipment, additional components may be added.

2. What is the difference to a photovoltaic system?

In contrast to photovoltaic systems, the much smaller plug-in solar devices are intended for private individuals to install, connect and use directly. You can also register with the network operator and the market master data register yourself. The mini solar systems can also be easily removed and continued to operate elsewhere, for example when moving. They have a power of up to 600 watts (inverter power).

Photovoltaic systems on private houses, on the other hand, have an output of between 3 and 20 kilowatts (kWp). They consist of several components, the installation and maintenance of which must be carried out by a specialist company who also handles the necessary technical inquiries and registrations with the local network operator. The PV system is permanently installed for permanent operation and can only be removed and moved to another building with considerable effort.

3. Is a plug-in solar device suitable for my apartment?

Basically, a plug-in solar device is suitable for apartments

• a balcony or
• a terrace or
• a roof area above the apartment or in front of the window, a garage roof or
• an external wall surface facing the sun.

A plug-in solar device is significantly cheaper than a photovoltaic system and can therefore also be financed by low earners.

You can also place a plug-in solar device on the terrace or in the garden. You can easily take the device with you when you move.

The following applies to rental and condominiums: If you want to attach the solar module to the balcony railing or the wall of the house, the landlord or the property community usually has to agree. Since the Home Ownership Act (WEG) was changed in 2020, unanimity is no longer required, only a majority approval.

Please note that in special cases, monument protection regulations may conflict with the project:

• For example, if there are listed objects in the immediate vicinity or
• in the listed town center or
• if building regulations conflict with the project. Keyword: overhead glazing.

4. Are plug-in solar devices safe?

The devices are generally very safe. At the end of 2021, over 190,000 such systems were already in operation in Germany. So far, not a single case of property damage or injured people has been reported. This is because the technology used is sophisticated and the same components are used in professionally installed photovoltaic systems. Only components manufactured and tested in accordance with standards may be used.

Plug-in solar devices are safe if the module inverters used meet the requirements that are also placed on inverters for normal photovoltaic systems. The installation standard also requires a qualified electrician to check the suitability of the circuit for feeding in solar power.

Above all, you should only ever connect a single plug-in solar device (an inverter) to a socket or circuit. Linking several devices via a multiple socket would be dangerous.

A product standard according to which the devices can be tested and certified is currently being developed. The DIN Consumer Council and the consumer advice center are also involved in this; publication was already expected in 2022 and is now scheduled for 2024. Until this product standard is published, you can, for example, base your purchase on the safety standard published by the German Society for Solar Energy (DGS).

You should also pay attention to the instructions for connection and use that manufacturers provide with the device. You should also learn from them how to securely attach the solar module and the inverter to the intended installation location.

5. How big are plug-in solar devices and which size is right for me?

By plug-in solar devices we mean 1 to 2 solar modules with an inverter that are connected to a household circuit.

These can be 1 to 2 standard solar modules (with a format of around 1 x 1.70 meters) of current design, each of which typically has a nominal output of between 350 and 420 watts. Over the next few years, the electrical performance of standard modules will continue to improve.

The 600 watts mentioned refer to the connected load of the inverter on the power grid side (AC). Two modules with 340 watts each or 2 modules with 420 watts each may also be operated, provided that the connected load of the inverter does not exceed 600 watts.

Alternatively, smaller, lighter solar modules are also available, which can be more easily attached to balcony railings, for example. These have 50 to 150 watts of power, and 2 to 4 of them can be connected to a micro inverter.

Tip: If you want to use as much solar power yourself as possible and avoid feeding it into the grid, we recommend an output of 200 to 400 watts, which is usually a standard solar module. If you would like to generate more solar power, you can also use 2 standard solar modules.

In principle, plug-in PV systems with higher output could also be built. Plug-in solar devices with, for example, 2,400 watts are now also available, but their inverters can also output a maximum of 600 watts. The consumer advice centers advise against this because it involves high costs, but only a small amount of electricity can be used through curtailment.

In our opinion, higher module outputs without limiting the inverter should be designed as a “real” PV system. At that point at the latest, a qualified electrician is required to check all the technical requirements of the power connection and register the device with the network operator.

However, the higher installation effort for a large photovoltaic system is usually only worthwhile financially for significantly larger system outputs of more than 3 kilowatts.

6. What is the use of a plug-in solar device? Is it worth it for me?

With a plug-in solar device, you can make your own personal contribution to the energy transition. The mini solar systems usually produce enough electricity to cover a significant portion of a household's base load and midday peak load on sunny days.

A standard solar module with 380 watts of power, mounted on a south-facing balcony without any shade, supplies around 280 kilowatt hours of electricity per year. This reduces your electricity consumption by about the same amount if you can use the electricity directly in your household.

This amount of electricity is roughly equivalent to the annual consumption of a refrigerator and a washing machine in a household with 2 people. With an average electricity price of 33 cents, this results in annual savings of around 66 euros.

A plug-in solar device with a standard module usually costs between 350 and 600 euros.

Since demand is currently very high and the delivery of components is delayed, prices are currently significantly higher in some cases. In return, electricity costs in households have also risen significantly in recent months. The yield of the device and thus its cost-effectiveness depend on various factors. These include the purchase costs, the orientation of the module with as little shading as possible and, of course, the current electricity price from the electricity supplier. It is particularly useful to install it vertically on the outside of a balcony parapet, which is oriented south-west to south-east without any shade. The vertical arrangement reduces unusable production peaks in summer and increases usable yields in the winter months.

For a location with average sunshine duration in Germany, you can estimate the economic viability of a plug-in solar device using the plug-in solar simulator from HTW Berlin .

Not only do you reduce your electricity bill, you also do something good for the environment: the mini solar system saves around 2.5 tons of CO2 emissions in 20 years.

Unsuitable installation locations are:

• behind the balcony railing in the balcony niche,
• on the wall under the balcony of the floor above,
• Places with shade, for example from trees, lamp posts or neighboring buildings.

Permanent, even partial, shading or contamination of the modules can lead to a reduction in yield, which has a significantly greater impact than with a photovoltaic system. You should therefore check your module regularly and remove dirt.

You can also find the most important information on this topic in this podcast from the NRW Consumer Center: https://player.podigee-cdn.net/podcast-player/podigee-podcast-player.html?v=378a2&id=pdg-3b3fb1b&iframeMode=script

7. Is there a subsidy for plug-in solar devices?

More and more municipalities, individual federal states and regional associations are supporting plug-in solar devices through grants. In addition, network operators and electricity suppliers are increasingly supporting this application by simplifying registration and not hindering use or even actively promoting such systems. But be careful: the funding conditions often also specify requirements, such as the use of a special power socket, the electrical installation being checked by an electrician or the assumption of installation costs for setting a new meter. In order to avoid problems with funding, these points must then be implemented.  

For plug-in solar devices, the EEG feed-in tariff is usually waived. For example, if a plug-in solar device generates 500 kilowatt hours of electricity annually and 150 kilowatt hours of that flow into the grid, that would mean a feed-in tariff of around 12 euros per year. This would then be offset by regular but disproportionately high meter reading and billing costs.

8. Where do I have to register a plug-in solar device?

In its EU Regulation 2016/631, the European Union classified small generators below 800 watts as “not significant” because they are “not systemically relevant”. Nevertheless, the German network operators want all generation systems, regardless of their output, to be reported to them. However, the company is not dependent on approval. They have written this requirement into the corresponding regulation (application rule VDE-AR-N 4105). A simplified form is intended for producers with up to 600 watts of AC power, which also includes plug-in solar devices according to our definition. After all, an electrician doesn't necessarily have to fill out this form; you can do it yourself if you use a plug-in solar device.

Many network operators make the simplified forms available on their website, and some send them on request. Some even offer particularly convenient online registration. When registering, you must include a data sheet for the inverter used, which shows that the device meets the requirements for connecting to the grid (declaration of conformity).

Some balcony module manufacturers offer assistance with registration.

Although it is controversial whether plug-in solar devices are actually “systems”, at least if these systems are not permanently connected but are connected to the circuit via a plug like household appliances, the Federal Network Agency also requires registration in the market master data register .

Two registrations are currently required: with the local electricity network operator and with the Federal Network Agency. It is important for these registrations that the same technical data, such as the performance or the date of commissioning, is entered both times, as the data is compared with each other in the background.

The registrations have no advantages for consumers, they only create bureaucratic effort. Since a plug-in solar device is also formally a grid-connected PV system, registrations are required. Failure to register in the market master data register can result in a fine.

Note: If you already have a PV system on your roof that is older than 12 months and some of its electricity is used in the household, the plug-in solar device should be seen as an additional new system. If it not installed on the same roof (with the same orientation and slope), the network operator will probably require an additional meter. Under these circumstances, operating the plug-in solar device becomes unprofitable . Only if the roof system is less than 12 months old (the commissioning date applies) can the plug-in solar device be subsequently registered as an extension of the existing system with the network operator and in the market master data register.

9. Do I need a new meter?

Even if plug-in solar devices are intended for personal consumption and not for feeding into the grid, electricity can still flow into the grid. Technically this is not a problem, and it is also allowed if you use inverters that comply with the standard.

The plug-in solar device could cause conventional electricity meters with mechanical turntables (“Ferraris meters”) to run backwards, because these meters are not equipped with a backstop. Therefore, in this case, the network operator, as the basic measuring point operator, exchanges the conventional meter for a modern electronic meter, which is also called a modern measuring device (mME).

These meters are available in two versions: Facility meters only measure the electricity consumption and do not count down when electricity flows into the network. The (small) excess feed-in is not measured with this meter variant.

The second option is a bidirectional counter. Technically, they are the same meters, but they are programmed in such a way that they record and display both counting directions - the electricity drawn from the network and the energy fed back into the network - separately. Such meters are also used in photovoltaic systems with surplus feed-in.

Over the next few years, the legislature stipulates that all electricity meters in Germany will be replaced by such modern measuring devices smart meter rollout

If your network operator removes the old meter and installs a modern measuring device instead, he is not allowed to charge any costs for this. The Metering Point Operation Act stipulates that the costs for installing and removing meters must be included in the annual metering price. When registering a plug-in solar device, many network operators agree to waive a bill for the meter.

If a modern measuring device is installed, the annual measuring costs can rise up to the legal maximum of 20 euros per year.

Make sure that your chosen electricity supplier or the basic supplier does not bill the metering costs twice as part of the basic price for electricity purchase.

10. What should I consider when purchasing?

From a technical point of view, it is very important that the included inverter contains a declaration of conformity in accordance with VDE AR ​​4105; only then can it be operated on the power grid. Also make sure that the inverter is limited to a maximum output power (AC power) of 600 watts (AC). The solar modules can have more power.

In individual cases, companies sell devices with open cable ends without a connector, for example. Customers are apparently supposed to install the plug themselves.

This means that manufacturing companies transfer responsibility for completing the product to the buyers. Legally, only a qualified electrician can do this, not someone without specialist knowledge. The same applies to replacing a socket: this must also be formally carried out by a qualified electrician.

When purchasing, the consumer advice centers recommend that you make sure that the manufacturers of the plug-in solar device comply with the DGS safety standard (DGS 0001:2019-10). A product standard for plug-in solar devices is expected to be available in 2024. It is currently being developed.

You can sometimes purchase mini solar systems, also known as balcony power plants, from local photovoltaic retailers. However, most offers are available in specialized online retailers. You can currently find market overviews on these websites:

• PV Magazine (photovoltaic trade magazine)
• Pvplug.de (German Society for Solar Energy eV)

You can now also find offers at discounters or electronics stores. However, these are usually significantly more expensive than the specialist retail offerings, and the advice and selection there are rather limited. Make sure that the offers are technically complete and that the substructure is also included, for example.

If all the requirements are met, you can plug in the device yourself. In some places, do-it-yourself workshops, which are carried out by regional energy cooperatives or other initiatives and people from the neighborhood who have already gained their own experience with plug-in solar devices, also help.

11. How do I know if it works and how much it does?

Solar modules or module inverters themselves do not directly indicate functionality or current performance. Sometimes the inverters have an LED that signals certain operating states by flashing or lighting up. However, this is not enough to see whether the device is running properly and what performance it is providing.

Some inverters include a power measurement that you can read and save using an external additional device. This may also work with an online connection to an internet portal, similar to photovoltaic systems (monitoring). Then some of the electricity generation can also be read on the cell phone.

If you connect via a Schuko plug in the socket - provided this is permitted for the device you have purchased - you can use a commercially available electricity meter, such as the one that can be plugged between the socket and the refrigerator, to determine the power consumption. Many of these devices can also measure in the opposite direction and are therefore also suitable as a generation counter for a plug-in solar device.

So-called “intelligent sockets” work according to the same principle, which can be switched via WLAN by the router or smart home controls and often also include energy measurement.

Neither electricity meters nor intelligent sockets are currently available for connection via the so-called “Wieland” special plug. In this case, you can have small electronics built into the socket to capture the data. These electronics also measure the current flow and send it to the internet router or smartphone via Bluetooth or WLAN.

When solar modules and inverters have become obsolete, you can take them to the local recycling center or sales point for disposal and recycling.

Checklist: Step by step to a plug-in solar device

1. Are the local conditions suitable for connecting a plug-in solar device? Is there as much sun as possible there?
2. Are the installation location, socket and circuit up to date?
3. Do the landlord or community of owners agree?
4. Are there any building or statutory restrictions, for example due to monument protection regulations in old town centers or overhead glazing?
5. What requirements does the network operator and any funding provider have?
6. Have you found the right offer that meets all your requirements? (Technology, price/performance, delivery, assembly and connection, DGS safety standard/future device standard)
7. Have you thought about monitoring to check performance?
8. Do you have experts or a local self-assembly group you can ask if you have any doubts?
9. Is everything clear with the registration and any necessary meter replacement?

Source:

Consumer advice center NRW

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