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Size a solar balcony system to the watts the house is already using in daylight, then stop at the plug-in limit in that country. For a typical flat, and for many houses, that is one module of about 450 W. A second module is for a higher daytime base load, not for a bigger bill. In Germany the inverter may feed in at most 800 VA, and the modules may total at most 2,000 W. A household socket is only in bounds up to 960 W of modules. The system covers the fridge, the router and standby. It does not run the house, a heat pump or a car.

The German environment agency, the Umweltbundesamt, updated this advice on 20 March 2026. Surplus from a plug-in system is exported without payment, so a larger array mostly gives power away at noon. The agency’s rule of thumb is that one module is usually the better financial size, because a flat’s continuous load is often well under 100 W and a house is only somewhat higher. East or west can still be a good railing. A battery on a system this small usually does not pay for itself.

What a solar balcony system actually covers

A balcony system, also called a plug-in solar device or Steckersolargerät, is one or two modules, a small inverter and a lead into the home’s own circuits. Generation and use have to overlap. At night the railing produces nothing. At noon, anything the house is not using at that minute leaves through the meter.

That is why the annual kilowatt-hour total on the bill is the wrong starting number. A house that uses 4,000 kWh a year does not need 4,000 kWh of balcony solar. Most of those kilowatt-hours are cooking, hot water, laundry and evening light, which a railing cannot follow. What it can follow is the load that is on while the sun is on the modules.

The Umweltbundesamt puts that continuous load under 100 W for an average flat, and a bit higher for a single-family house. A module rated around 450 W will sit above that load for a large part of a bright day, which is why a second module often adds exported energy rather than saved energy. Use a year’s bills only to see whether anyone is home at midday. If the house is empty until evening, almost every extra watt is a gift to the grid.

One module or two

Start with one module when the daytime load is ordinary: refrigeration, a router, a laptop, chargers. Add a second when you can point to a daytime load that will actually absorb it, such as someone working from home, a freezer in the shade of the kitchen, or a small always-on appliance the first module cannot cover. Do not add it because the balcony has room.

Orientation changes the shape of the day, not the logic. South-facing modules, in the northern hemisphere, produce the most energy over the year. East-facing modules produce more in the morning, west-facing more late in the day, which can line up better with when people are in the kitchen. A module fixed vertically on a railing produces less across the year than the same module at a tilted optimum. The Umweltbundesamt’s simplified hours are 950 full-load hours for a well-tilted south array and about 665 for a vertical mount, roughly 30% less. Shade from the slab above, a neighbouring block or the railing itself can take more than the tilt does. A shaded second module is not a larger system. It is a heavier railing.

Their worked case is specific to Germany and should stay labelled as theirs. An 800 W system mounted vertically is put at 532 kWh a year. Without a battery, about 45% of that is used in the house at the same time, about 240 kWh. At an energy price of 37 cents per kWh that is just under €90 a year. At a purchase price of €400, the simple payback is just under five years. Those euros are an illustration for that price and that mount. They are not a quote, and they do not travel to another tariff.

The practical calculator for a German balcony, wall or small roof is the HTW Berlin Stecker-Solar-Simulator, which is the tool the environment agency points to. Outside Germany, use a local yield tool and the local plug-in rule. Do not paste the German euros onto another bill.

The inverter cap, not the house

Germany is the clearest published ceiling, and it is a ceiling on the hardware, not on the building.

LimitWhat it applies to
800 VA at the inverterThe most a layperson may commission under VDE-AR-N 4105, as the Umweltbundesamt states it. This is the feed-in, not the module sticker.
2,000 W of modulesThe simplified Marktstammdatenregister path for a plug-in plant that gives up the feed-in tariff. Module power may sit above the inverter so cloudy hours still produce.
960 W of modules on a household plugA normal Schuko socket is in bounds only up to this module power, and only if the device meets DIN VDE V 0126-95, including the extra plug protections that norm requires.
Above 960 W of modulesAn energy connector, such as a Wieland device, or a fixed connection by an electrician. The inverter is still capped at 800 VA on the simplified path.

Register the plant in the Marktstammdatenregister within a month of the first time it feeds the house. Since the Solar Package took effect on 16 May 2024, a plug-in plant inside those power values that waives the feed-in tariff does not also have to be filed with the distribution company. The register notifies them. Two plugs do not double the allowance: the simplified class is the combined inverter power and the combined module power.

Never feed the house through a multi-socket adapter. The environment agency flags that as a fire risk. A standard glass module is about 1.8 m by 1.0 m and about 20 kg, and the railing also has to take the wind load. Cable ties are not a mount. If the railing or the bracket cannot be shown to take that load, the right size is zero until the structure is checked.

Other countries do not inherit 800 VA. A UK, US or Philippine socket has its own notification limit, plug rules and voltage. Copying the German number onto a different grid is how a small system becomes an unapproved generator. Read the local rule before you read a kit advert.

When the balcony is the wrong system

Buy a rooftop system, not a larger balcony kit, when the house has a roof you control and the load you care about is a heat pump, an EV charger, electric cooking or whole-evening backup. An 800 VA feed cannot do those jobs. The Umweltbundesamt is also blunt about batteries on plug-in systems: a large share of the energy is already used at the moment it is made, winter surplus is too small to fill a battery, and round-trip losses sit on top of a short warranty relative to the price. Home storage can still be right on a proper rooftop array. It is usually the wrong add-on for a railing.

A north-facing railing with no direct sun, a balcony someone must walk past, or a landlord’s refusal that is actually about structure rather than taste, are also stops. In Germany a tenant or apartment owner still asks permission, but since the tenancy and condominium law changes a refusal needs a serious reason. Permission is not a structural calculation. The 20 kg and the wind load still have to land on something that can hold them.

If the project has already grown past a plug, the inverter choice changes category. That decision is in how to pick a PV inverter for a house, a commercial building or a plant, and in string inverter versus microinverter once the array is a roof rather than a railing.

Which ShineTong inverter fits a balcony

ShineTong does not sell a consumer balcony kit, a plug, or the modules. We supply microinverters to distributors and installers who build the system. The AC nameplate has to sit inside the local cap. On a German plug-in job that means 800 VA or less.

  • ST-500M is rated 500 W or 600 W AC, depending on the SKU. Both sit under an 800 VA cap. Maximum DC input is 60 V, maximum input current 14 A, output 220–240 V, enclosure IP67, operating range −40°C to 65°C.
  • ST-1200D spans 800 W to 1,600 W AC across the series. Only an 800 W unit is at the German plug-in ceiling. A 1,200 W or 1,600 W unit is a small roof inverter, not a Steckersolargerät. DC maximum is 60 V, input current 16 A, 220–240 V, IP67, −40°C to 65°C.
  • ST-2800Q is 2,000 W to 2,800 W AC. It is above the German plug-in class. Use it on a roof that is allowed to be that large, not on a household socket.

A 220–240 V output matches the European voltage family. It is not, by itself, approval for Germany or for any other country. Ask for the certificate that names the SKU and the grid code you need, including VDE-AR-N 4105 where that is the rule. A module’s short-circuit current also has to fit the input: 14 A on the ST-500M is tight for some newer high-current modules. The product page states a 25-year warranty on these series. We do not publish a balcony-kit price, because we are not selling the kit.

Specifying the inverter for a plug-in system? Send the module count, the local AC limit and the country.

Frequently asked questions

What size solar balcony system does a house need?

Usually one module of about 450 W, or two if the daytime base load will use the extra power. In Germany keep the inverter at or below 800 VA and the modules at or below 2,000 W, and keep a normal household plug at or below 960 W of modules. Size it to the load that is on while the sun is out, not to the annual bill.

Is 800 W of inverter the same as 800 W of panels?

No. The 800 VA figure is what the inverter may put into the house wiring. The modules on the simplified German path may add up to 2,000 W, so the array can still produce in weak light while the inverter clips at the legal feed-in. A household socket is a third number: 960 W of modules.

Should a balcony system include a battery?

Usually no. The Umweltbundesamt’s view is that much of the energy is used as it is made, that winter surplus is a poor way to fill a battery, and that the cost and the losses are hard to earn back on a system this small. Storage belongs with a rooftop system whose surplus is large enough to move.

Can a balcony system power a whole house?

No. It offsets a small continuous load. It will not carry a heat pump, an electric cooker, an EV charger or a night-time peak. If that is the job, design a rooftop array and pick the inverter for that array.

Do the German limits apply in other countries?

No. The 800 VA inverter, the 2,000 W module total and the 960 W household-plug line are German rules, from VDE-AR-N 4105, the Marktstammdatenregister path and DIN VDE V 0126-95. Another country can set a different notification limit, forbid plug-in feed-in, or require an electrician for any size. Check that rule before you order.

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