Balcony power - Everything you need to know

Zero feed-in for balcony storage: How to avoid giving away a single cent to your grid operator with Shelly & Co. Anyone who buys a balcony power plant with storage today does so primarily for one reason: they want to drastically reduce their electricity costs and become more independent from their local energy provider. But anyone who uses the standard settings of most manufacturers quickly realizes what the catch is. Usually, only a fixed nightly output – the so-called base load – can be set in the app, for example, a constant 150 watts. The problem is obvious: If the refrigerator switches off at night, 50 watts suddenly flow uncompensated into the public grid. If the coffee machine switches on in the morning, it draws 1,500 watts – and you have to buy expensive grid electricity, even though your battery is full. The solution to this dilemma is dynamic zero feed-in. In this guide, you will learn step-by-step how to achieve precise real-time consumption measurement with the help of a Shelly 3EM integration, allowing you to throttle or dynamically increase your feed-in power. This way, you maximize your self-consumption rate to almost 100 percent. The problem of rigid base load: Why you're giving away hard-earned money Most plug-and-play solar systems (balcony power plants) with batteries work with rigid profiles ex-factory. You estimate your nightly consumption and enter this value into the app from Anker, Zendure, EcoFlow, or Growatt. However, this method is extremely inefficient: The "giveaway effect": If your actual consumption in an hour is below the set value (e.g., because the heating pump is paused), the surplus electricity from your expensively paid-for storage is fed into the grid. With a balcony power plant, there is usually no compensation for this. The "buy-in effect": As soon as a larger consumer like the dishwasher, washing machine, or even just the kettle switches on, the rigid feed-in is far from sufficient. You only cover a fraction and pay the full electricity price, often over 35 cents per kilowatt-hour, for the rest. This makes a real financial amortization of the storage system a distant prospect. To operate the system economically, it must adapt to the behavior of your household appliances in a matter of seconds. The solution: Dynamic zero feed-in through real-time consumption measurement The magic formula is: Generation = Consumption. The goal is to keep the electricity meter at the grid connection point ideally at exactly 0 watts. If your house consumes 432 watts, the storage must supply exactly 432 watts. If consumption drops to 80 watts, the system must react immediately. For this real-time consumption measurement, the Shelly 3EM (or its successor, the Shelly Pro 3EM) has established itself as a de facto standard in the German PV community. This smart measuring device is installed by an electrician directly in the fuse box (metering point). Using three clamp current transformers, it measures the current flow on all three phases of your household grid contactlessly and extremely precisely – in both directions (consumption and feed-in). Since the Shelly measures in a balancing manner (just like your grid operator's official electricity meter), your system knows the absolute grid load at every millisecond. This data is the foundation for being able to throttle or dynamically increase feed-in power. Step-by-step: How Shelly 3EM integration works To transfer the data from the Shelly 3EM to your balcony power plant storage, there are two primary ways in 2026: the native manufacturer interface or the overarching Smart Home system. Method A: Native Cloud-to-Cloud or Local Integration by Manufacturers Many reputable manufacturers have recognized the potential and offer a direct link to Shelly accounts in their apps. Installation: The Shelly 3EM measures the main connection. Pairing: In the app of your storage system (e.g., Zendure or Anker), select Shelly as the "Smart Meter" manufacturer and log in. Automation: The system retrieves consumption data via the cloud or local WLAN and automatically regulates the output of the micro-inverter every 3 to 10 seconds. Method B: The Brain in the House – Home Assistant or ioBroker (Recommendation for Pros) Those who seek maximum independence from manufacturer servers and want to avoid the so-called "cloud dependency" rely on local control via Home Assistant. The Shelly 3EM delivers data via MQTT or native integration completely locally and without delay to Home Assistant. A script (often based on Node-RED or pre-made blueprints) continuously calculates the current surplus or demand. The command to throttle or adjust the feed-in power is sent via the local API or an open-source firmware of the inverter/storage. The advantage of Method B: Regulation is often significantly faster (under 2 seconds) and works even if your internet provider experiences an outage. Practical example: What happens when the coffee machine is switched on? Let's look at a concrete scenario to illustrate how much money you save with this setup: Time / Action Household Base Load Coffee Machine Shelly 3EM Measurement Storage Reaction Grid Draw / Loss 07:00 (Idle) 150 W OFF +150 W Supplies exactly 150 W 0 W 07:01 (Coffee brewing) 150 W +1400 W +1550 W Increases to 800 W (Limit) 750 W bought (instead of 1400 W) 07:03 (Finished) 150 W OFF -650 W (as storage still supplies) Detects surplus, throttles to 150 W 0 W (no giveaway) Without this dynamic regulation, with a rigid setting of 150 watts, you would have drawn a full 1,400 watts from the grid during the brewing process, even though your battery was full. After brewing, if you had chosen a rigid load that was too high (e.g., 400 watts), you would have given away valuable battery power to the public grid. Conclusion: Is the effort worth it? The installation of a Shelly 3EM, including electrician costs, usually ranges between 150 and 250 Euros. With an estimated additional saving of 50 to 80 Euros per year due to avoided incorrect feed-in and optimized self-consumption, the measuring device pays for itself in less than three years. Anyone operating a balcony storage system today without intelligent real-time consumption measurement is leaving the greatest potential of the energy transition on their own balcony unused. The Shelly 3EM integration is the key to being able to throttle feed-in power whenever necessary – and thus effectively avoid giving away a single cent more to the grid operator. Frequently Asked Questions (FAQ) 1. Do I absolutely need an electrician for the Shelly 3EM? Yes, absolutely. The Shelly 3EM (or Pro 3EM) is connected directly in the fuse box to the main phases, either before or directly after the official electricity meter. Since this involves life-threatening voltages of 230V or 400V (three-phase current) and the protection is located before the main fuses, installation by laypersons is prohibited. A qualified electrician usually completes the installation of the current transformer clamps and the connection of the power supply in under 45 minutes. 2. What happens if my balcony storage feeds into Phase 1, but the coffee machine runs on Phase 3? Thanks to the principle of balancing meters in Germany, this is no problem at all. All modern electricity meters from grid operators mathematically sum the currents of the three phases. If you feed in exactly 800 watts on Phase 1 and consume exactly 800 watts on Phase 3, the main meter effectively reads exactly 0 watts. The Shelly 3EM also perfectly handles this phase balancing and transmits the total value to your feed-in management system. 3. How quickly does dynamic zero feed-in react to rapid changes? The reaction speed heavily depends on your setup. If you use a pure cloud-to-cloud solution (Shelly sends to the cloud -> manufacturer server processes -> command to inverter), the delay can be between 5 and 15 seconds. With rapid load changes, such as when an induction hob cycles, this can lead to brief overshoots or undershoots. If, however, you use a completely local control via Home Assistant and MQTT, the adjustment often occurs in under 1 to 2 seconds. 4. Can I just use smart plugs instead of the Shelly 3EM? Technically, yes, but with massive limitations. If you only use smart plugs (e.g., Shelly Plug S) for your washing machine and refrigerator, your storage system will only see the consumption of those specific devices. All "invisible" consumers like ceiling lights, the router, standby devices, or the extractor hood will not be recorded. True, fully automatic zero feed-in for the entire household can only be achieved by measuring directly at the meter point via a Shelly 3EM. 5. Does dynamic zero feed-in violate the 800-watt limit of the Solar Package I? No, as long as the maximum output power of your micro-inverter does not exceed the legal limit of 800 watts (or VA) at any time, either through software or hardware. The dynamic regulation merely ensures that the inverter is intelligently controlled within the range between 0 and 800 watts. If your house requires 1,500 watts, the inverter will still cap at 800 watts – so you are completely on the safe side legally.

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How many watts does a solar panel produce per day? Yield, factors & practical values for Germany. The energy transition has long been taking place on our own roofs and balconies. Anyone considering buying a photovoltaic system or a balcony power plant inevitably asks themselves: How many watts does a solar panel produce per day? To clear up a technical misunderstanding right away: A solar panel does not produce "watts" over the course of a day (that is the pure power at a certain point in time), but watt-hours (Wh) or kilowatt-hours (kWh) – i.e., electrical energy. In this guide, you will learn based on real practical data for Germany what solar yield you can really expect in summer, winter and on an annual average. The most important influencing factors on daily PV yield The yield of a solar panel is not a rigid constant. How much electricity ends up in your household appliances or in the electricity storage at the end of the day depends on a number of physical and geographical variables: Global radiation (solar irradiation): In Germany, the irradiation differs greatly between north and south. While the north averages around 950 to 1,000 kWh per square meter per year, the sunny south (Bavaria and Baden-Württemberg) often reaches over 1,150 kWh. The tilt angle and orientation: Optimal for year-round yield in Germany is a pure south orientation with a tilt angle between 30° and 45°. An east-west orientation provides less peak power at noon, but distributes the yield more evenly over the day (ideal for self-consumption in the morning and evening). The degree of shading: Even partial shading of a single module by a chimney, trees or power lines can drastically reduce the yield of the entire series (string), unless modern bypass diodes or module optimizers are installed. The temperature (the temperature coefficient): Solar panels like it bright, but cool. As temperatures rise, the efficiency of the solar cells decreases. A crisp, cold, sunny day in April can therefore generate more power per hour than a hot midsummer day in July. What does a 400-watt solar panel produce per day? A standard solar panel for residential buildings usually has a nominal output of around 400 watt-peak (Wp). This is the maximum output under standardized laboratory conditions (STC: 1,000 W/m² irradiation, 25 °C cell temperature). In German practice, the reality is as follows: On an ideal summer day (May to August): An unshaded, optimally oriented 400 Wp module delivers 4 to 5 times its nominal output as daily yield. This corresponds to approx. 1,600 to 2,000 watt-hours (1.6 to 2.0 kWh) per day. This allows you to run a washing machine about twice at 60 °C. On a gloomy winter day (November to February): Here the factor drops drastically to 0.1 to 0.5 times. The module often produces only 40 to 200 watt-hours (0.04 to 0.2 kWh) per day. The annual average: Over the entire year (365 days including all bad weather days), a 400 Wp module in Germany generates approx. 1 kWh of electricity per day. What does an 800-watt balcony power plant produce per day? Balcony power plants (also called plug-in solar systems) are the trend in Germany. Since the legal adjustments, these systems are officially allowed to feed in with an inverter output of up to 800 watts. Usually, two solar modules with a total output of approx. 800 to 850 Wp are installed. Since balcony power plants are often mounted vertically on the balcony railing (90° angle), the yields deviate slightly from the optimal roof pitch. Typical daily yields of an 800W balcony power plant: Weather condition / Season Average daily yield (in kWh) What you can operate with it (example) Perfect summer day (south-facing, cloudless) 3.5 to 4.5 kWh A modern refrigerator (24h) + home office workstation (8h) + several washing machine loads. Cloudy spring day / Autumn day 1.5 to 2.5 kWh Covering the continuous base load of the house (router, standby devices, refrigerator). Gray, foggy winter day 0.2 to 0.6 kWh Often only enough to cover the inverter's self-consumption and minimal standby consumption. Practical tip: If you mount your balcony power plant steeply at a 90° angle on the balcony, the peak yield in summer will decrease, but you will capture the lower-lying sun much more effectively in winter and during the transitional months. What is the maximum daily PV yield? Can a photovoltaic system produce an infinite amount of electricity if the sun shines continuously? No, physical limits set a clear boundary here. The maximum daily PV yield is limited by the maximum daylight duration and the physical peak power. In Germany, the absolute maximum on a perfect June day is about 6 to 7 kWh yield per installed kilowatt-peak (kWp) system capacity. If you have a small system with 4 kWp, the absolute maximum is approx. 24 to 28 kWh on one day. Higher values are hardly technically feasible in Central Europe due to the sun's position and the unavoidable heating of the modules during the day. Solar radiation in annual comparison The biggest dilemma of photovoltaics in Germany is the seasonal imbalance. The following graphic illustrates how extreme the monthly generation differences in Germany are over the years:   As can be clearly seen in the diagram of monthly solar generation, electricity production is almost entirely concentrated in the months of April to September. In late autumn and winter, yields plummet massively nationwide. How much electricity does a 10 kWp photovoltaic system produce per day in winter? A 10 kWp system (approx. 24 to 25 modern solar modules on a single-family house) is the classic homeowner size in Germany. While such a system easily generates 60 to 70 kWh on a single day in June, the situation in winter is completely different. In winter (December and January), we have to contend with two main factors: extremely short days (often only 7 to 8 hours of daylight) and a very low sun angle, often combined with a thick cloud or fog cover. The winter daily yield of a 10 kWp system in detail: On a sunny winter day (with clear sky): If the sky clears and the sun shines on the cold modules, a 10 kWp system can achieve 10 to 15 kWh per day even in January. On a typically gray, rainy or snowy winter day: Unfortunately, this is the standard in German winter. In diffuse light, the performance collapses. The system then often produces only 2 to 5 kWh per day. With snow-covered modules: If a thick layer of snow covers the modules, no light reaches the solar cells. The yield drops to 0 watts. As a rule of thumb: a PV system generates only 10 to 15% of its total annual yield in the four months from November to February combined. Operating a heat pump or an electric car purely with solar power is impossible in these months without drawing from the grid. Conclusion: Is the purchase worthwhile despite the fluctuations? Yes, absolutely. Even if the daily yield drops sharply in winter, the summer more than compensates for these deficits. Anyone who consumes the electricity produced during the day themselves through clever consumption management (e.g., running the washing machine and dishwasher at noon) or by using a battery storage system will drastically reduce their electricity bill. At current electricity prices in Germany, an optimally planned photovoltaic system usually pays for itself after 8 to 12 years – and then supplies free, clean electricity for at least two decades. FAQ – Frequently asked questions about solar module yield 1. Does a solar module also produce electricity when it is cloudy? Yes. Solar modules do not need direct, dazzling sunlight to generate electricity. They also use what is called diffuse light, which breaks through the cloud cover. However, the yield is significantly lower in heavy cloud cover – it often amounts to only 10% to 25% of the output that would be achieved in clear skies. 2. What is the difference between watts (W) and watt-hours (Wh)? Watts (W) or kilowatts (kW) is the unit of measurement for instantaneous power – i.e., how much power the module generates at that exact second. Watt-hours (Wh) or kilowatt-hours (kWh) measure the energy/quantity that has been produced over a period of time. If a module constantly delivers 400 watts for one hour, it has generated 400 watt-hours (0.4 kWh) of electricity. 3. Does heat harm solar modules in summer? Indeed, yes. Solar modules have a so-called temperature coefficient (usually approx. -0.35% per degree Celsius). As soon as the solar cells heat up above the standard test temperature of 25 °C – which quickly leads to cell temperatures of 60 °C on the roof on hot summer days – the maximum performance of the module decreases. The highest peak performances are therefore often measured on cool, windy, but sunny days in April or May. 4. Is an inverter with more watts than the solar modules worthwhile? No, as a rule, not. In practice, it is even common and sensible to slightly "undersize" the inverter. This means that the solar modules collectively provide, for example, 900 watt-peak, but the inverter is limited to 800 watts. Since the modules rarely reach their theoretical peak performance in Germany anyway due to heat and weather conditions, the inverter operates in a more efficient operating range throughout the year due to the slight undersizing. 5. How much electricity does a PV system lose over the years? Modern solar modules are subject to minimal aging, which is called degradation. Reputable manufacturers today guarantee that the modules will still deliver at least 80% to 85% of their original nominal output after 25 years of operation. The annual power loss averages only 0.3% to 0.5%, which is hardly noticeable in everyday life.

2, 4 or more modules for an 800W balcony power plant? 🔋 Discover the trick of overpanelling and how to find the perfect number for your household.

The popularity of balcony power plants (plug-in solar systems) in Germany remains unbroken. The federal government's Solar Package I massively reduced bureaucratic hurdles. But despite all the simplifications, one topic remains a mystery to many operators: grounding and equipotential bonding. Many ask themselves: Is simply plugging into the Schuko socket sufficient, or is there a risk of electric shock or fire in the event of a lightning strike? In this comprehensive guide, you will learn everything about the legal obligations, technical implementation options, and receive precise instructions. Grounding a balcony power plant: Obligation or option? The question of whether grounding a balcony power plant is an obligation cannot be answered with a simple yes or no. A strict distinction must be made between functional grounding (protective conductor via the power grid) and lightning protection or additional equipotential bonding of the mounting frame. 1. The protective conductor (PE) via the socket (mandatory) Every inverter approved in Germany (e.g., from Hoymiles, Anker, or Deye) has an AC connection. Via the connection cable – whether a conventional Schuko plug or a special Wieland plug – the inverter's housing is automatically connected to the protective conductor (PE, the green-yellow wire) of your house installation. This is absolutely mandatory and is ensured by the CE certificate and the NA protection of the inverter. 2. Grounding of the aluminum mounting frame (DIN VDE 0100-712) This is where confusion often arises. Standard DIN VDE 0100-712 stipulates that metallic substructures of PV systems must be integrated into the functional equipotential bonding of the building. When is it mandatory? If the balcony power plant is located in an area that is at risk of lightning strikes (e.g., on a roof, an exposed roof terrace, or if the building has a lightning protection system). When is it a strong recommendation? For a standard installation on a balcony railing on the 2nd floor. It protects against the entire metal railing of the balcony becoming live in the event of a defect (e.g., a frayed cable). Grounding a balcony power plant: How does it work technically? When we talk about how to ground a balcony power plant, the core issue is to establish a conductive connection between the solar module frames, the mounting frame, and the earth. Aluminum (from which most frames and rails are made) forms an insulating anodized layer in the air. A simple screw connection is therefore often not sufficient to reliably conduct electrical current. The tools for standard-compliant grounding: Grounding clamps / grounding pins: These have small metal spikes (usually made of stainless steel) that bite through the anodized layer of the module frame when tightened to establish direct metallic contact. Grounding cable: For pure equipotential bonding (protection against contact voltage), a copper, green-yellow conductor with a cross-section of at least $6\text{ mm}^2$ is required. If the system is also to be protected against lightning currents (functional grounding for lightning protection systems), a cross-section of $16\text{ mm}^2$ (copper) or $8\text{ mm}$ (aluminum/steel) is prescribed. Balcony Power Plant Grounding Instructions: Step-by-Step If you have decided to set up additional equipotential bonding for your balcony power plant, you can follow these practical instructions. ⚠️ Important safety note: Work on the 230V household network or the main earthing bar (HES) of the house may only be carried out in Germany by a registered electrician according to § 13 NAV! However, you can carry out the mechanical preparation of the frame yourself. Step 1: Connect the module frames to each other Connect the aluminum frames of the solar modules to the mounting frame. Use special grounding plates or grounding clamps that penetrate the anodized layer. Step 2: Secure the grounding cable to the frame Attach a green-yellow solar cable (at least $6\text{ mm}^2$ copper) firmly to the mounting frame using a certified grounding clamp (e.g., from Schletter or K2). Step 3: Connection to the Main Equipotential Bonding Bar (HES) Route the grounding cable by the shortest route into the building or into the basement to the house's main equipotential bonding bar (HES). Connect it to a free slot there. If a direct route to the HES is not possible, a connection to the sub-distribution (green-yellow rail in the fuse box) can be checked in consultation with an electrician. Special situations in practice Grounding balcony power plant via the gutter – allowed? The question balcony power plant grounding gutter is very often read in DIY forums. The clear answer from an electrical engineering perspective is: No, that is not permissible and dangerous. A gutter or downpipe is not a defined earth electrode. The individual segments are often only plugged together, glued, or isolated from each other by dirt and oxidation. There is no permanent, lightning current-carrying connection to the earth. Anyone who connects their balcony power plant to the gutter risks the entire drainage system of the house being put under high voltage in the event of a fault or lightning strike. Balcony power plant grounding via an earth rod If the balcony power plant is located in the garden (e.g., on the lawn, a bracket on the terrace or the garage roof), the balcony power plant grounding earth rod is an excellent option. This involves driving a cross earth rod or deep earth rod (usually 1.5 to 2 meters long, made of hot-dip galvanized steel or stainless steel) into the ground. The mounting frame is then connected directly to this earth rod with a solid grounding wire. Important: This separate earth electrode should ideally also be connected to the rest of the equipotential bonding of the residential building to avoid dangerous potential differences (voltage displacement) between inside and outside. Special feature: Grounding balcony power plant 4 modules (large systems up to 2000W) Since Solar Package I, balcony power plants are allowed to have a module output of up to 2000 watts (peak), while the inverter feeds in at 800 watts. This often leads to configurations with 4 modules. With grounding a balcony power plant with 4 modules, the metallic surface increases dramatically. The following must be observed: Looping: All 4 module frames must be seamlessly conductively connected to each other. It is not sufficient to ground only one rail if the modules are mounted in isolation. Cable management: Since significantly more DC cables (direct current) are laid with 4 modules, they must be neatly tied up. They must not touch sharp metal edges to prevent earth faults due to frayed insulation over the years. Conclusion: Safe operation through professional installation A balcony power plant is a full-fledged power plant. While the inverter protects itself via the normal power cable, additional grounding of the metal frame provides a decisive plus in safety. Those who build on the ground floor or in the garden can work well with an earth rod. Those who go high up on the roof or to the facade cannot avoid proper integration into the household equipotential bonding. In case of doubt, always have an electrician inspect the system – safety first! Frequently asked questions 1. Is grounding via a normal Schuko plug sufficient? Yes, for the internal protection of the inverter. The inverter dissipates fault currents from its housing via the Schuko plug. However, the aluminum frame on which the modules rest is not grounded by this. 2. What happens if I don't provide additional grounding for my balcony power plant? In most cases (e.g., protected mounting on a concrete balcony on the 1st floor), nothing happens, as the modules are protective insulated. However, if a cable is damaged and touches the ungrounded metal frame, the structure will be live. Touching the frame can then result in an electric shock. 3. Can I ground the frame to the balcony railing? Only if the balcony railing itself is demonstrably firmly integrated into the building's equipotential bonding system. This is often the case in modern new buildings, but rarely in older buildings. If the railing is not grounded, in the worst case, you could transfer the fault to the entire railing. 4. What cable cross-section do I need for equipotential bonding? For pure protective equipotential bonding without lightning protection, VDE requires a cross-section of at least $6\text{ mm}^2$ copper (green-yellow). 5. Is a Wieland plug safer in terms of grounding than a Schuko plug? In terms of grounding (the protective conductor), both plugs are absolutely equivalent. The Wieland plug merely offers touch protection on the pins when unplugged, which is also prevented with a Schuko plug by the prescribed NA protection (switch-off in less than 200 milliseconds) in the inverter. 6. How do I connect the solar modules when they are next to each other? You use so-called module mid-clamps with integrated grounding plates (grounding pins). These plates have small claws that, when the modules are tightened, simultaneously bite into both frames, thus creating the electrical bridge. 7. Can I leave a balcony power plant plugged in during a thunderstorm? Yes, a normal thunderstorm will not damage the system. However, in the event of a direct lightning strike in the immediate vicinity, only professional surge protection (Type 1 / Type 2) in the fuse box will help protect the inverter from extreme overvoltage. 8. Does the grounding have to be approved by the grid operator or the market master data register? No. Neither the Federal Network Agency (Market Master Data Register) nor the grid operator checks the physical grounding of your frame. However, as the system operator, you are responsible for its safe and standard-compliant condition (according to VDE).

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

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