The electricity grid is not a freely usable system, even if the connection point is on the wall of a family house. The moment a solar panel system connects to the public grid, it is no longer merely a technical issue, but also a legal one. The logic of the law is simple: anything that affects the grid belongs to a regulated environment.
Therefore, it is not enough for the system to be technically sound and for the inverter to start up. Only a system that connects according to the prescribed procedure, with permission and with proper metering, is lawful.
What happens legally with a residential solar panel system?
When a household installs a solar panel system, the user not only remains a consumer but also becomes an active participant, as they generate electricity and can feed it back into the grid. The law treats this as an active user status.
This status is not automatic. It requires the knowledge and approval of the grid operator. An already operating system cannot be regulated retrospectively with the excuse that only administrative tasks were left undone. The permit is a prerequisite, not a retrospective formality.
Grid connection is not a formality
The law states that the connection of equipment to the public grid is regulated. The grid operator is entitled to set conditions, limit capacity, and define the technical framework of the connection.
In practice, this means that as an installer, you cannot independently decide whether a system can feed back. The correct order is always the same: grid connection application, service provider approval, then installation and commissioning. If this order is disrupted, the system becomes unlawful, and the responsibility does not rest solely with the customer.
Capacity limits
The law authorizes grid operators to take into account the state of the grid and, based on this, to set capacity limits. This means that even if more panels could fit on the roof, and even if the inverter could handle it, the grid operator may only allow a certain capacity. An oversized, unpermitted design may work in the short term, but it is legally indefensible.
Unauthorised modification
In the eyes of the law, not only the initial installation matters. Any modification that could affect the grid may require a permit. This includes, for example, the subsequent addition of panels, replacing the inverter with a larger one, changing the feed-in settings, or connecting a battery that also affects the grid.
It is often said that it is only a few panels, or only a technical repair has taken place. Legally, however, what matters is whether the impact on the grid has changed. If so, the new state no longer matches the permitted one.
Metering point and billing
According to the law, the billing of electricity is based on certified metering. In practice, this means a bidirectional meter, which is managed by the service provider. Until the meter replacement has taken place, the system cannot feed back.
It happens that the system is physically complete, and the customer wants to use the generation during the day. Legally, however, feed-in is not permitted before a meter replacement. As an installer, the safe and lawful procedure in such cases is not to commission the system before official approval and meter replacement.
Responsibility
Based on the legal practice behind the law, the installer has professional responsibility. It is not sufficient to claim that the customer requested the modification, or that others do it this way. In the event of a possible accident, fire, or grid problem, it will be investigated whether the system was connected correctly, whether there was a permit, and whether it complied with the regulations.
A signed statement does not absolve you of professional obligations. Responsibility is shared but does not disappear.
What does this mean in practice for a residential installer?
A grid-connected system can only operate with a permit. No feed-in before a permit. We do not modify the permitted state without approval. The metering point is a legal element, not merely a technical detail. And documentation is not administration, but proof.
