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Little sun catchers: If many households produce a little electricity in an uncomplicated way, a lot is gained in the end - this is the basic idea behind plug-in solar systems

Photo: Robert Poorten / IMAGO

MIRROR: Mr. Lange, the Federal Ministry of Justice wants to simplify the installation of balcony solar systems with a new draft law. A bill from the Ministry of Economics is intended to reduce practical hurdles. Can everyone start installing now?

Long: Unfortunately, the ministries are not removing all the obstacles that make it impossible for some consumers to install a balcony solar system – even if we are happy about the partial success. In addition, these are bills that can still change. Until they are adopted, the previous, complicated legal situation applies.

MIRROR: Then would it be better to wait if you are interested in a plug-in solar system?

Long: No. If you want a new balcony power plant this summer, you can already get suitable components for almost every application. It is not without reason that the devices are already being sold very successfully. Before that, however, you should clarify a few points in advance. If you are still unsure, you may want to wait until next year until the last points have been clarified or simplified. On the other hand, every system installed quickly is a small contribution to the local energy transition – and for the users themselves, too, because they save electricity costs from day one.

MIRROR: Then let's go through the tricky points. What should you pay attention to now?

Long: First of all, you need a suitable place for new solar panels. It should be shaded as little as possible and regularly get many hours of sun. In multi-family buildings, the consent of the landlord or co-owners has so far also had to be obtained.

MIRROR: This is where the Department of Justice has come in.

Long: Exactly. With the change in the law, balcony solar systems will soon be considered legally privileged. So far, one has been dependent on the goodwill of the landlord or the community of owners. You could opt out of the installation without having to give any further reasons. With the privilege, consent can only be prevented for serious reasons. And it's not enough not to like the surface of solar panels. None of this speaks against the plants.

MIRROR: So I don't have to ask anyone once the law is passed?

Long: It also makes sense to at least let us know beforehand.

MIRROR: In the case of damage, it is usually a question of whether the system is insured. What is the situation on this point?

»Anyone who uses an inverter with a suitable CE mark is already on the safe side today.«

Long: So far, only very few significant damages have been reported. In any case, the operator of a balcony solar system is responsible for any damage caused to third parties by the system. After all, this is the case with all household appliances. Therefore, it is important to clarify in advance that damage caused by plug-in solar devices, as balcony power plants are officially called, is covered by your own liability insurance. They are already included in most contracts. In the event of fire or storm damage, household contents insurance could help, which should also be checked.

MIRROR: What are the risks associated with balcony power plants?

Long: On the one hand, it is about electrical safety, on the other hand, it is about secure attachment to the building. In the area of electrical safety, standardization has largely been completed. Anyone who uses an inverter that converts the direct current from the panels into grid-compatible alternating current with a suitable CE mark is already on the safe side here.

MIRROR: One safety issue that caused uncertainty was the question of suitable plugs.

Long: The experts at the VDE or the Federal Network Agency agree on this: A special plug for plug-in solar devices is not necessary. The situation is different when mounting the solar modules, for example on a balcony railing. So far, there is no easy-to-recognize marking for suitable systems.

MIRROR: So if something goes wrong with the assembly, you can't just say: I assembled everything according to the instructions, the manufacturer has grumbled and is responsible.

Long: Exactly. At the turn of the year, the product standard DIN VDE V 0126-95 should be ready, in which the generally accepted rules of technology are recorded. If they are then complied with, it is not only helpful in court. We hope, for example, that the standard will require manufacturers of mounting kits to specify the application for which the respective set is suitable. This then includes information on the permissible module weight, the installation height and the wind load zone. In order to be able to provide this information, the manufacturer must provide appropriate evidence. If these are available, the manufacturer is liable for the safety of the mounting solution.

MIRROR: What should I pay attention to until the standard is completed?

Long: Installation on a building is subject to building law. Up to an overall height of four meters overhead for balconies – the upper edge counts – the CE certification for conventional glass/glass or glass/foil modules is sufficient. If you want to use modules over four meters, you can look for modules with general building authority approval and must expect that they are among the more expensive devices, for example from Solarwatt or Kyoto Solar. Alternatively, lightweight plastic modules can already be used today. These are a bit more expensive and a little less durable, but they are much easier to handle thanks to their low weight.

MIRROR: What is the practical impact of the current legal situation?

Long: We know of housing companies that impose countless conditions on their tenants for the construction of a solar power plant. For example, some require a static report to ensure that the balcony railing also supports the system. The appraisals are usually so expensive that a balcony system is then no longer worthwhile and usually means the end for the system. The structural analysis is not trivial, it is not only about the weight of the panels, but about the forces acting in storms and snow. And especially in the case of old buildings, it may be that a balcony or railing cannot withstand certain constructions.

MIRROR: How to deal with it?

Long: From our point of view, the owner should be responsible for the safety of the balcony and the railings and, in case of doubt, have an expert opinion on the load-bearing capacity of the balcony prepared himself. Then he can make suitable specifications for the fastening of the modules and the angle of attack for permissible installations. In the meantime, there are the aforementioned plastic modules, which weigh a few kilograms and for which no significant additional load on the balcony is usually to be expected when mounted vertically. If an expert opinion should come to the conclusion that the balcony is not suitable even for these lightweights, a renovation or reinforcement of the balcony is probably necessary anyway.

MIRROR: Balcony power plants have to be registered, right?

"In our experience, the majority of users today do not comply with the double registration requirement."

Long: Yes, I don't need a permit, but I have to register my plug-in solar device. And according to current law, twice, namely with the network operator and the market master data register. In our experience, the majority of users today do not comply with the double registration requirement. With the new regulation, as planned by the Ministry of Economic Affairs, this will become easier. You will then only have to report to the market master data register, i.e. to the Federal Network Agency, and the reporting form will no longer be as complicated as before.

MIRROR: How do you bill for electricity that you don't consume yourself?

Long: Theoretically, you could get a feed-in tariff for this, but in practice, the technical effort has not yet been worthwhile for such small plants as the balcony power plants. After all, the surplus electricity benefits everyone because fewer fossil fuels are needed and because it slightly reduces the price of electricity due to the higher supply.

MIRROR: How does it work with the counter?

Long: In most houses, there are still meters with old technology that simply run backwards when there is excess electricity. Strictly speaking, this has been prohibited so far. With the new law from the Federal Ministry of Economics, this is to be tolerated within the framework of plug-in systems until a regular change takes place at no additional cost. By 2025, every customer who wants to get a smart electricity meter from their grid operator for a maximum of 20 euros per year anyway. By then, at the latest, electricity consumption and surplus feed-in can be billed correctly separately. From 2032, these smart meters will be mandatory.

MIRROR: Many grid operators insist on changing the meter when installing a balcony power plant.

Long: Legally, it is like this: If a modern meter is installed during a regular meter change, network operators are not allowed to charge extra costs for it. However, whether this applies if the change is made specifically for the balcony power plant is currently being examined by an arbitration board. There is still a lack of legal certainty here, even if it involves comparatively low costs.

MIRROR: There has been a lot of discussion about whether systems with 800 watts of power should also be allowed. So far, the limit is 600 watts.

Long: I think it is likely that the 800 watts will come, they are also in the draft law of the Ministry of Economics. After all, they are also standard in neighbouring European countries. Until then, however, you are only allowed to feed in a maximum of 600 watts, which is guaranteed by the inverters approved today.

MIRROR: This means that if you install now, you will have to retrofit later?

Long: No, this is only an upper limit value for the power fed into the inverter. If you want, you can work with an 800-watt inverter later, but the economy will hardly increase with 800 watts, since the self-consumption share can only be slightly increased by higher powers. In addition, the 600 watts are only reached on a few hours a year, the peak value only describes the maximum possible power under laboratory conditions. In practice, where diffuse light, shading and orientation of the modules play a role, this value is rarely achieved.