The Big Electricity Meter FAQ for Balcony Power Plants

The energy transition for one's own balcony is in full swing. Thousands of Germans are installing mini solar systems to save electricity costs and become more independent. But with the anticipation of one's own solar power come the questions – and most of them revolve around an often underestimated component: the electricity meter.

Can my old meter stay? Who pays for the replacement? And what exactly is a bidirectional meter? The confusion is great, but the answers are often simpler than expected. In this comprehensive FAQ, we answer the 20 most pressing questions about electricity meters and balcony power plants, so that you can produce your own electricity safely, legally, and without worries.

1. Which electricity meter is required for a balcony power plant?

For the legal operation of a balcony power plant, you need an electricity meter that does not run backward when feeding electricity into the grid. This means you need either:

• A modern digital electricity meter (modern metering device) with an integrated reverse lock. This is the standard today.

• A bidirectional meter, which measures the electricity drawn and fed in separately.

• An old Ferraris meter with a symbol for a reverse lock.

An old mechanical meter without this lock is not permitted and must be replaced.

2. Can my old, black Ferraris meter continue to run for a balcony power plant?

That depends. An old, black Ferraris meter (with the mechanical rotating disc) is only temporarily permitted if it has a reverse lock. You can recognize this by a small symbol, which usually depicts a gear with a pawl. If this symbol is missing, the meter would run backward when feeding in, which is forbidden. In this case, a replacement is unavoidable and will be initiated by the grid operator after registration.

3. What happens if my electricity meter runs backward and what penalties are threatened?

A backward-running electricity meter manipulates the measurement of your electricity consumption. This is legally considered an administrative offense and in some cases even tax evasion (as electricity tax is not correctly paid). Even if harsh penalties are rare, the consequences are unpleasant:

• Request for immediate meter exchange.

• Recalculation of consumption: The grid operator will estimate the incorrectly credited electricity and bill you retroactively.

• Possible fines by the Federal Network Agency.

It's not a trivial offense. Therefore, it is crucial to commission the system only after ensuring a correct meter.

4. Who pays for the replacement of the electricity meter for my balcony power plant?

One of the best pieces of news for aspiring solar producers: The electricity meter is the property of the metering point operator (usually your local grid operator). If a replacement becomes necessary as part of the registration of your balcony power plant, it is in most cases completely free of charge for you. The grid operator bears the costs for the meter and its installation.

5. How do I know if my electricity meter has a reverse lock?

For digital electricity meters, a reverse lock is always integrated. You do not need to check anything further here.

For old Ferraris meters, you must look for a specific symbol on the dial. Look for a small pictogram that resembles a gear with a type of hook or a pawl. If you find this symbol, your meter has a reverse lock. If not, it will run backward.

6. What is a bidirectional meter and is it mandatory for an 800-watt balcony power plant?

A bidirectional meter is a digital meter with two separate registers:

• Register 1.8.0: Measures the electricity you draw from the grid (your consumption).

• Register 2.8.0: Measures the electricity your balcony power plant feeds into the grid.

There is currently no legal obligation for a bidirectional meter for balcony power plants. A simple digital meter with a reverse lock is sufficient. In practice, however, many grid operators proactively and free of charge install a bidirectional meter directly after registration, as this is the technically cleanest solution.

7. Do I have to wait for the meter exchange before I can commission my balcony power plant?

That depends on your current meter:

• If you already have a digital meter or a meter with a reverse lock, you can commission your system directly after registering with the grid operator and in the market master data register.

• If you have an old meter without a reverse lock, you must absolutely wait for the exchange by the grid operator. Commissioning would be illegal.

8. How do I register my balcony power plant correctly so that the meter is checked?

The process has been greatly simplified thanks to Solar Package I:

1. Registration in the Market Master Data Register (MaStR): You must do this online yourself. It only takes a few minutes.

2. Registration with the grid operator: Most grid operators offer a simple online form for this. Here you enter your data and the capacity of the system.

Through this registration, the grid operator is automatically informed about your system and internally checks whether a meter exchange is necessary for you.

9. What is the difference between a digital meter and an intelligent metering system (Smart Meter)?

A digital meter (modern metering device) is the basic version. It measures electricity consumption digitally and has a display, but no external communication function.

An intelligent metering system (Smart Meter) is a digital meter that is supplemented by a communication module (the Smart Meter Gateway). This gateway sends the consumption data encrypted and automatically to the grid operator. This enables, for example, a daily consumption overview via an app. For balcony power plants, a Smart Meter is not required, but it is the most future-proof technology.

10. Do I get money for the electricity that my bidirectional meter measures as feed-in?

No, for the electricity fed in by a balcony power plant, there is no feed-in tariff according to the Renewable Energy Sources Act (EEG). The electricity recorded on meter 2.8.0 is "given" to the grid. The entire financial benefit of your system arises exclusively from the reduction of your own electricity consumption.

11. How do I correctly read my digital or bidirectional meter?

With a bidirectional meter, you will see various values on the digital display, which are referred to as OBIS codes:

• 1.8.0: Shows the total amount of electricity drawn from the grid in kilowatt-hours (kWh). This is the value relevant for your electricity bill.

• 2.8.0: Shows the total amount of electricity fed into the grid. You can usually find this value by pressing a button on the meter.

12. My balcony power plant is registered, but the grid operator has not responded. What now?

Here the simplified rules of Solar Package I apply. After your registration, the grid operator has one month to contact you if they consider the meter unsuitable and want to carry out an exchange. If they do not respond within this period, it is considered tacit consent. You can then commission the system (provided your meter does not run backward).

13. Is a meter with a reverse lock sufficient, or does it have to be a bidirectional meter?

Legally, a meter with a reverse lock is completely sufficient. You are effectively giving away surplus electricity invisibly to the grid, but you are acting completely legally. A bidirectional meter is the more transparent, but not a mandatory solution.

14. Does the electricity meter affect the performance of my balcony power plant?

No, the electricity meter has no influence whatsoever on the electricity production or the performance of your solar modules or your inverter. The meter is a pure measuring instrument. It only measures what flows past it; it does not slow down or promote the flow of electricity.

15. My electricity provider installed a new digital meter – am I now ready for a balcony power plant?

Yes, most likely! If a new, digital electricity meter was recently installed at your premises, it meets all technical requirements. It is guaranteed to have a reverse lock. However, you must of course still register your system as prescribed in the market master data register and with the grid operator.

16. Can the grid operator prohibit the installation of a balcony power plant because of the meter?

No, the grid operator cannot prohibit operation. However, it can and will prohibit operation with an unsuitable meter (without a reverse lock) until the exchange has taken place. Since the grid operator is responsible for the meter, it is their duty to provide you with a suitable meter after registration.

17. I live in a rented apartment – who is responsible for the meter exchange, me or my landlord?

Neither! The contact person for all matters concerning the electricity meter is always the metering point operator (grid operator), not your landlord. The electricity meter is part of the grid infrastructure. As a tenant, you only need to inform your landlord about the installation of the balcony power plant on the building structure and obtain their consent. The registration and any meter exchange then take place directly between you and the grid operator.

18. What are the annual costs of a modern digital electricity meter?

The annual fee for metering point operation is legally capped. For a modern metering device (digital meter), the operator may charge a maximum of 20 euros per year. You usually already pay this fee today via your electricity bill, even for an old meter. The costs therefore hardly change due to the change.

19. Does a balcony power plant also reduce the meter reading at night?

No. A balcony power plant needs sunlight to generate electricity. At night or in very strong darkness, it does not produce electricity. During this time, you draw all your electricity as usual from the public grid, and the meter counts forward normally. A reduction in the meter reading only occurs during the day when the sun is shining.

20. Is a balcony power plant worthwhile even if I "give away" surplus electricity to the grid operator?

Yes, absolutely! The business model of a balcony power plant is not based on feeding in, but on maximizing self-consumption. Every kilowatt-hour you generate yourself and consume directly means you don't have to buy it expensively (currently often over 30 cents) from your electricity provider. The savings are enormous even if you give away some electricity on sunny midday hours. The focus is on covering your household's base load (refrigerator, standby devices, etc.) during the day with free solar power.