Registering a balcony solar system: step-by-step guide
Introduction
You have bought a balcony solar system and want to put it into operation. But first you have to register it. Since 2024, registration has become much simpler: a single registration in the Marktstammdatenregister is sufficient. Here you can find out how it works step by step.
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Where do I have to register my balcony solar system?
Marktstammdatenregister (MaStR)
The only mandatory registration for balcony solar systems is the Bundesnetzagentur’s Marktstammdatenregister.
- Website: marktstammdatenregister.de
- Cost: No fee
- Duration: 15–30 minutes
- Deadline: Within one month of commissioning
Grid operator notification (no longer required since 2024)
Since the Solarpaket I (May 2024), separate notification to the grid operator is no longer necessary. The Bundesnetzagentur automatically forwards the data.
Previously (up to 2024): Two registrations required (MaStR + grid operator)
Now (from 2024): MaStR only
Step by step: registering in the Marktstammdatenregister
Step 1: Create an account
- Go to marktstammdatenregister.de
- Click “Registrierung”
- Enter your email address and a password
- Confirm the email
Step 2: Enter operator details
- Name and address of the system operator (you)
- Date of birth
- Contact details (email, telephone)
Step 3: Register the system
- Type of system: Solar system
- Type: Plug-in solar device (balcony solar system)
- Output: Inverter output in watts (e.g. 800 W)
- Module output: Total output of the solar modules in watt peak (e.g. 1.600 Wp)
- Location: Address of the installation
- Commissioning date: When you first plugged in the system
Step 4: Confirmation
After registration you will receive a MaStR number. Keep this safe: it is your proof that you have registered correctly.
What data do you need?
| Information | Where to find it |
|---|---|
| Inverter output (W) | Datasheet or rating plate of the inverter |
| Module output (Wp) | Datasheet for the solar modules |
| Commissioning date | Day of first plugging in |
| Location | Your address |
| Meter number | Electricity meter in the mains connection room |
Do I have to inform my landlord?
Since Solarpaket I (2024) a balcony power plant has been classed as a privileged structural alteration. This means:
- The landlord cannot refuse the installation without good reason
- However, you must inform the landlord beforehand (duty to notify)
- A written application is recommended (email is sufficient)
- The landlord can refuse only for objective reasons (e.g. structural stability, listed-building protection)
For owner-occupied flats (WEG)
- Here too: privileged measure since 2024
- The owners’ association must be informed
- A WEG resolution is generally not necessary
- Exception: where there are structural interventions in common property
Meter replacement: what applies 2026?
Old Ferraris meter (spinning disc)
If you still have an old meter, it is allowed to run backwards. The network operator will replace it with a modern bidirectional meter at no additional charge, but only when they get round to it.
You do not have to wait for the replacement. You are allowed to operate the system immediately.
Modern meter
- Bidirectional meter: Measures consumption and feed-in separately - ideal
- Smart meter: Is being installed gradually, compatible
Deadlines and consequences
| Topic | Deadline / rule |
|---|---|
| MaStR registration | Within 1 month after commissioning |
| Network operator notification | No longer required since 2024 |
| Landlord notification | Before installation |
| Failure to register | Administrative offence, fine up to 50.000 € (in theory) |
In practice: The fine for failure to register is rarely imposed. Even so, you should not put off registering: it only takes a few minutes and can be done free of charge.
Frequently asked questions
Do I have to register my balcony power plant with the Finanzamt?
No. Since 2023, balcony power plants up to 30 kWp have been exempt from income tax. Business registration is not necessary. VAT on the purchase has also been 0 % since 2023.
What if I am already operating my balcony power plant but have not registered it yet?
Do it immediately. Go to marktstammdatenregister.de and register the system. Enter the commissioning date retroactively.
Do I need an electrician for the registration?
No. Registration in the MaStR is a purely online process. You also do not need an electrician for the installation itself if you have a Schuko socket. For a Wieland socket, a specialist company is recommended.
Can I register several balcony power plants?
Yes. Each system is registered separately in the MaStR. However, a limit of 800 W inverter output applies per residential unit for the simplified registration.
Summary
- Only requirement: Marktstammdatenregister (free of charge, online)
- Network operator: No longer required since 2024 (automatic forwarding)
- Deadline: 1 month after commissioning
- Landlord: Inform, but no right of veto
- Finanzamt: No registration required (tax-free)
- Time required: 15-30 minutes
Related Tips
- Balcony power station: what is permitted? Rules 2026
- Apply for a balcony power station grant
- Connecting a balcony power station: guide