Small balcony and garden solar systems: what they can do and what to check

Solar cells are usually made of silicon. When light falls on them, it sets electrical charges moving in the material – producing direct current, meaning current that always flows in the same direction. The home's circuits, however, work with alternating current. A device called an inverter therefore converts the direct current so it can be used in the home.

With a grid-tied plug-in solar unit, this electricity flows into the home's circuits. Appliances that are running use it first, and correspondingly less is drawn from the public grid. Without storage, solar power is only used while the sun shines. How much a panel delivers depends heavily on orientation, tilt, season, weather and shade – even partial shading can reduce output noticeably.

If the public grid fails, grid-tied inverters shut down. This is a deliberate protective function: no voltage may flow back into a de-energised grid where professionals are working. So such a unit is generally not a source of backup power during a power cut.

For preparedness this is the key insight: cutting electricity costs and having backup power are two different goals that need different systems. A balcony system reduces grid consumption in everyday life. For backup power – charging a phone, a lamp, a radio – you need an off-grid system that works independently of the grid, or a portable power station that can be charged with a solar panel.

For most households, a power station with a folding panel is the simpler emergency solution: it is a ready-made device, is not connected to the home's wiring and supplies small devices through its own outlets. Its battery is limited, though. Large loads such as fan heaters, cookers or kettles drain it quickly or overload it. The manufacturer's information shows which devices it can supply.

Self-built battery systems or arrangements that somehow feed a system into the home's wiring during a power cut are dangerous and belong exclusively in the hands of qualified electricians.

Plug-in solar units have spread widely in some countries. But the rules differ considerably between countries and keep changing: whether and where the system must be registered, what power is allowed, which plug and which meter are required. That is why this text deliberately gives no figures or legal positions.

Before buying, therefore, find out the current local requirements, for example from the grid operator or official bodies. In rented homes and owners' associations, the consent of the landlord or association is often needed, especially if something is fixed to the facade or railing. Comply with any notification and registration duties.

For mounting and connection: use only complete kits with manufacturer instructions, follow them exactly, and connect only as locally permitted. If a fixed cable, a special socket or a change to the home's installation is needed, a qualified electrician does it.

The biggest danger is often not the electricity but the wind. Panels are heavy and present a large surface for gusts to push against. A falling panel can seriously injure people. It is fixed only with mounts designed for the purpose, according to the manufacturer's instructions, and the fixing must be suitable for the load. Nothing is mounted above walkways or entrances without a verified installation. Check the mounting after storms.

As for electricity: no DIY wiring, no tampering with inverters or the home installation. Solar panels produce voltage as soon as light falls on them – you cannot simply switch them off. Damaged cables or plugs are not patched up but replaced by professionals.

Batteries in power stations and storage systems hold a lot of energy. Charge and store them only per the manufacturer's instructions, do not use damaged or swollen units, and do not place them in escape routes such as hallways or stairwells.

One household wants to save on electricity costs and has a sunny south-facing balcony: here a plug-in solar unit can make sense – after checking the rules, with consent and secure mounting. For a power cut, the same household also plans torches, power banks or a power station.

Another household lives on the ground floor with a shady courtyard: a fixed panel there often brings little. A power station with a folding panel that can be put in a sunny spot when needed can still be useful for preparedness. The honest question at the start is always: what do I want to achieve – saving or preparing?