miniJOULE 2023 Balcony Power Plant

miniJOULE is a decentralised energy source, also known as a balcony power plant or plug-in solar system.

Depending on the version, a miniJOULE consists of one or two 370 Wp solar modules, a 300W or 600W inverter, and corresponding connection and small parts. A robust mounting structure can also be optionally ordered.

The maximum capacity of a balcony power plant is limited to 600 watts. There must be no risk of electric shock. Electricity meters must not run backward and may need to be replaced by the responsible metering point operator if necessary. The inverter must be certified with NA protection (network and plant protection). Each household (meter of the metering point operator) may operate only one miniJOULE. Tenants should check with the property owner beforehand if installation is allowed.

Users are allowed to self-register and install plug-and-play balcony power plants like miniJOULE up to 600 watts. However, their components must meet the safety guidelines of the respective grid operator, such as compliance with VDE-AR-N 4105. Generally, the connection can be made to a standard Schuko socket (in some cases, grid operators may require a specifically designed, currently compliant energy device: Wieland socket). We still recommend having the circuit checked by an electrician beforehand and reviewing the grid operator's safety guidelines. It should be noted that faulty installations can lead to personal injury and property damage.

For more information, see the VDE press release from January 23, 2023.

Yes, balcony power plants like miniJOULE must be registered with the relevant grid operator and in the Market Master Data Register of the Federal Network Agency. These registrations must be completed before commissioning.

If a 350-watt system generating 350 kWh per year costs €440 (excluding mounting structure), it would save €140 annually at a rate of €0.40 per kWh. In this case, the miniJOULE would pay for itself in about three years. The annual output depends on various factors such as location, orientation, season, shading, etc.

With subsidies like those in Schleswig-Holstein, where up to €200 is provided, the system could pay for itself in just two years.

Technically, generated electricity can be sold under EEG guidelines. However, this comes with much higher reporting and requirement obligations, which often do not justify the resulting compensation. Since the savings from self-use are much higher, selling the electricity is not advisable. Excess power is fed into the grid without compensation, and the annual loss from free feeding is typically minimal. Some subsidy programs, such as in Schleswig-Holstein, prohibit feeding power into the grid.

No, miniJOULE inverters are grid-tied and require the house network's frequency. Only after synchronisation can the inverter feed power. Synchronization cannot happen during a power outage.

When fully assembled, each module occupies approximately 180 cm x 110 cm and weighs around 30 kg. For a 600 W miniJOULE Double, the required space doubles. Please consider this when choosing an installation location.

Components are delivered via a freight carrier, who will contact you using the provided contact information to arrange a delivery date.

Please note that the delivery will be made on at least one Euro pallet, and the access route must be suitable for this.