Connecting a Balcony Power Plant Storage System: Guide, Costs & Inverter Tricks

How is the storage connected to a balcony power plant?

Balcony power plants have brought the energy transition into German households. But those who work during the day often give away valuable solar power to the public grid – completely free of charge. The solution? A battery storage system. But how is the storage connected to the balcony power plant, what do you need to pay attention to when wiring, and when is it even economically worthwhile?

In this comprehensive guide, you will learn everything you need to know about the installation, the functionality of inverters, and the economic viability of balcony power plant storage systems.

1. The Basics: How does a balcony power plant with storage work?

A classic balcony power plant consists of solar panels and a micro-inverter that converts the generated direct current (DC) into household-standard alternating current (AC). If a storage unit (battery) is connected in between, the energy flow changes:

1. Energy generation: The solar modules generate direct current during the day.

2. Storage & distribution: The electricity first flows into the storage system (often a LiFePO4 battery). An intelligent control unit decides how much electricity flows directly into the house and how much is temporarily stored in the battery.

3. Feed-in: Only when electricity is needed in the house (or the storage unit is full) does the system forward the electricity to the inverter, which makes it usable for your home grid.

2. Step-by-Step Guide: How to connect the storage to your balcony power plant?

Modern storage systems (such as those from Anker, EcoFlow, or Zendure) are fortunately designed as plug-and-play systems. You do not need an electrician for standard installation.

Step 1: Take safety precautions

Disconnect all components from the power grid. Unplug the Schuko or Wieland plug of the inverter from the socket. Ideally, cover the solar modules to prevent a voltage spike during wiring.

Step 2: Connect solar modules to the storage unit

The MC4 output cables of your solar modules are no longer plugged directly into the inverter, but into the designated inputs (PV-In) of the storage unit. Pay attention to the correct connection of positive (+) and negative (-) poles.

Step 3: Connect storage unit to the inverter

From the output of the storage unit, special MC4 connection cables lead to the inputs of the inverter. The storage unit acts here as a "controllable solar cell" for the inverter.

Step 4: Connect inverter to the house grid

Reconnect the AC output cable of the inverter to your household socket (Schuko or Wieland).

Step 5: Commissioning and app configuration

Switch on the system. Most modern storage units have a Bluetooth or WLAN interface. Using the associated smartphone app, you can now set how many watts (e.g., the base load of your house of 150 watts) should be permanently supplied to the inverter.

3. The Inverter in Focus: Power requirements and connections

To avoid installation errors, one must understand how the core component – the inverter – works. We repeatedly receive specific questions on this topic:

Where does the inverter get its power from?

In normal operation without a battery, the inverter draws its energy directly from the solar modules. As soon as light falls on the panels, a voltage is built up that "wakes up" the inverter.

If a storage unit is connected in between, the inverter gets its power from the storage unit. The battery simulates a constant solar radiation for the inverter.

What power does an inverter need? (Self-consumption)

An inverter not only generates electricity, it also consumes a small amount itself. This so-called self-consumption or standby consumption for modern micro-inverters (such as those from Hoymiles, TSUN, or Deye) is about 1 to 5 watts. At night, when no energy is fed in, the devices switch to a deep standby mode, in which they draw almost no power from the public grid (usually less than 0.5 watts).

Can an inverter be connected directly?

Yes, but only to the solar modules or the designated storage output. > ⚠️ Important Safety Note: You must never connect the DC input of a conventional micro-inverter directly to a car battery or a rigid battery system without a charge controller/battery management system (BMS)! Since batteries, unlike solar modules, can deliver extremely high currents, there is a risk that the inverter will burn out or that a fire will occur. Therefore, only use certified plug-and-play storage units that electronically regulate the power output.

4. Blackout Scenario: What happens to the inverter during a power outage?

A widespread misconception among German consumers is that a balcony power plant with storage will automatically continue to supply the house during a power outage.

Behavior during a power outage

If the public power grid fails, the inverter automatically switches off within milliseconds. This is legally mandatory according to the standard VDE-AR-N 4105 (the so-called NA protection). The reason: If technicians are working on the power grid to fix the fault, balcony power plants must not feed electricity into the lines, as this would be life-threatening.

The Exception: Emergency power-capable storage units

The normal inverter therefore stops working during a power outage – even if the sun is shining and the battery is full. If you want real emergency power, you need a storage system that has a separate AC emergency power output (e.g., an integrated socket on the storage unit itself). You can then directly operate devices such as smartphones or cool boxes at this socket during a blackout, independently of the house grid.

5. Economic Viability and Usefulness: When is a solar storage unit worthwhile?

A storage unit increases self-sufficiency but comes with additional acquisition costs. Therefore, the question of economic benefit arises.

When is a storage unit useful for a balcony power plant?

A storage unit is always useful when your usage behavior does not match the generation profile of the solar modules.

• Less useful: You work in a home office, use a washing machine, dishwasher, and air conditioning during the day. Your direct consumption is already very high.

• Very useful: The apartment is empty between 8:00 AM and 5:00 PM. The balcony power plant diligently produces electricity that flows unused into the grid. In the evening, you come home, cook, watch TV, and consume electricity when the sun has already set. Here, the storage unit captures the daytime peaks and releases them in the evening.

When does a solar storage unit pay for itself?

The amortization period depends on three factors: the acquisition costs of the storage unit, your electricity price, and optimal sizing.

Thanks to the abolition of VAT (0% tax rate for PV components in Germany), storage units have become significantly cheaper. A simple example calculation:

• Capacity: 1.6 kWh storage

• Costs: approx. 600 to 800 euros

• Additional savings: With the storage unit, you use approx. 250 to 300 kWh more yourself annually, instead of giving it away.

• Savings in euros: At an electricity price of 35 cents/kWh, this corresponds to an annual saving of around 90 to 105 euros.

Conclusion on amortization: Such a storage unit currently pays for itself after approximately 6 to 8 years. Since modern LiFePO4 batteries are designed for over 3,000 to 6,000 charging cycles (which corresponds to a lifespan of 15 to 20 years), you will make significant profits after the amortization phase.

6. Frequently Asked Questions (FAQ)

Can I connect any inverter to a balcony power plant storage unit?

In principle yes, as long as it is a standard micro-inverter (e.g., from Hoymiles, Anker, or APSystems) that works with MC4 connectors and whose voltage ranges (V) match the output specifications of the storage unit. Most all-in-one storage units on the German market are universally compatible.

Can I leave the storage unit outside on the balcony in winter?

This depends on the battery technology and the protection class. Most storage units use lithium iron phosphate cells (LiFePO4). These often cannot be charged at temperatures below 0 °C, as this would damage the cells. Many high-quality outdoor storage units therefore have integrated heating. If your storage unit does not have this, it should be placed in a frost-free room (e.g., cellar or utility room) in winter.

Do I have to register the storage unit with the market master data register (MaStR)?

Yes. If you register your balcony power plant in the market master data register of the Federal Network Agency (which is legally mandatory), you must also indicate whether a battery storage unit is present and what capacity it has. Registration has been greatly simplified thanks to Solar Package I and now only takes a few minutes.

How many watts should I set as feed-in in the app?

Orient yourself to your so-called base load. This is the electricity consumption that your house permanently has when no one is actively using devices (refrigerator, standby devices, WLAN router). For a single or couple household, this is usually between 100 and 150 watts, for families often between 200 and 250 watts. Set this value as the permanent output at the storage unit to purchase as little electricity as possible.

Can the storage unit explode due to overcharging?

With modern brand storage units, this is practically impossible. They use LiFePO4 cells, which are considered extremely safe and thermally stable (unlike older lithium-ion batteries from smartphones). In addition, an integrated battery management system (BMS) continuously monitors the temperature, voltage, and charge status of each individual cell and immediately switches off the system in case of irregularities.

Can I combine several storage units if my needs increase?

Yes, most reputable manufacturers offer a modular system. Using special extension cables, additional battery blocks can simply be stacked on top of each other or connected side-by-side (e.g., extending from 1.6 kWh to 3.2 kWh or more) without having to buy a new inverter.

Disclaimer: This article was written to the best of our knowledge and taking into account the current VDE guidelines and legal situation in Germany (as of 2026). Technical installations should always be carried out according to the manufacturer's instructions.