As “balcony power plants” are meant small “Plug & Play” photovoltaic systems with an output of less than 800 watts, which are being plugged into appropriate power connectors and of which the generated electrical energy is fed into the household network.
The advantage of these systems is that their operation does not require approval from the electricity grid operator and that no particular electrical skills are required for their connection.
If used correctly, these devices can help a household to consume self-generated sustainable electricity and to reduce the need to purchase energy from its electricity supplier, which can result in cost savings.
However, in order for these advantages to occur, a few things must be considered when connecting such a system.

Three-phase network
Almost all households in Luxembourg have a three-phase mains connection, which consists of three live conductors (L1, L2, L3) behind the electricity meter, as well as a neutral conductor (N) and a grounding conductor (PE).
While the electricity meter belongs to the electricity grid operator and is maintained and read by him, the electricity grid operator is not responsible for the technical installation behind the electricity meter.
Instead, it is the professional electrician’s responsibility to ensure that the installation behind the electricity meter conforms to technical regulations; in particular, the “Technical connection conditions for high-voltage systems with a nominal voltage of up to 1.000V in the Grand Duchy of Luxembourg” must be respected.
During the electrical installation of a household, the electrician has to make sure that the circuits in a new building (or in the case of a renovation or extension) are distributed evenly over the three phases L1, L2 and L3 so that none of the three phases is disproportionately overloaded. In this context, one speaks of avoiding an “unbalanced load”. According to Article 9.1 of the above mentioned technical connection conditions, the maximum permissible asymmetry limit of 4,6 kVA between two phases at the connection point must be respected at all times.

Electricity meter
The intelligent “Smarty” electricity meter, installed in a household, measures all electrical energy that flows into the household from the grid, but it does not measure the energy that is transmitted through each of the three phases (L1, L2 and L3) individually.
Because no separate electricity meter is installed for a Plug & Play system, no dedicated measurement occurs of the electrical energy generated by such device. The electrical energy, generated by such a system, thus flows into the overall household without being measured.
However, the Smarty electricity meters have a compensatory effect, which means that the consumption (import) can be reduced by the simultaneous feed-in (export) of electrical energy from a Plug & Play PV system, even if the consumption is distributed over several phases and regardless of which phase the Plug & Play PV system is connected to.
Nevertheless, if the production of electrical energy is bigger than the current consumption in the household and a surplus of energy is therefore generated by a Plug & Play PV system, the household will not be reimbursed by the grid operator for the energy fed into the grid.

You can share the electricity you produce with other consumers.

When sharing within the same building, you can create a sharing group in form of a “self-consumer of renewable energies acting collectively”. When sharing with consumers located elsewhere, you can create or join an energy community. However, certain conditions must be met and you should contact your grid operator as soon as the project begins to take shape, in particular to conclude a self-consumption agreement.
In both cases, the meter values of the members of the sharing group will be recalculated for each quarter-hour to reflect the sharing principles you have defined.

Example: during a given quarter-hour, your production unit produces 500 Wh (Watt-hour) while you consume 200 Wh yourself. The excess 300 Wh can be allocated to one or more members of your sharing group. Their network consumption, which is used as the basis for billing the energy supplied by the supplier, will thus be reduced by these 300 Wh.

You have several criteria (priority, percentage, pro rata) to determine how your surplus can be distributed. The relevant forms are available on your grid operator’s website.

For energy communities, more complex sharing criteria are possible.

Find out more about energy sharing at www.weshareenergy.lu.

Producing electricity from renewable energy sources contributes to climate protection, increases the country’s autonomy and allows the production to be used in several ways.

In addition to the benefits of selling the energy produced and fed into the network, self-consumption is both economic and ecological. It allows renewable electricity to be consumed when it is available, thus avoiding the need to rely on the network to deliver the energy needed and avoiding all the costs associated with supplying electricity from the network. This makes the citizen less dependent on network supply and the vagaries of market prices, while at the same time providing the assurance of being able to benefit from the networks when needed. In this context, self-consumed renewable electricity is not subject to any charges or fees: neither the network usage tariff, nor the contribution to the compensation mechanism or the electricity tax are applied to self-consumed electricity.

Producing and consuming your own electricity therefore has several advantages, both for you and for the community.

In general, but even more so in times of high energy market prices, it is almost always financially advantageous to install a photovoltaic power plant and to consume as much of the electricity produced as possible by shifting consumption to the times when the plant is producing, i.e. when the sun is shining. The advantage for the self-consumer is that they are able to benefit from electricity that they have produced themselves produced for which the unit cost is lower than the price of electricity purchased on the markets and delivered through the network. In addition, it is 100% produced from renewable sources.

Furthermore, it is important to remember the beneficial effects for the community. Firstly, the production of electricity from renewable sources reduces climate change emissions and dependence on fossil fuels and/or imported energy. In addition, the ability to shift consumption to times when on-site renewable generation is abundant reduces the load on the network, both because the generation does not have to be fully absorbed by the network and because the displaced consumption reduces the load at other times.

Under these conditions, self-consumption therefore makes an important contribution to energy transition.

Nevertheless, to make an active contribution to climate protection, we must remain attentive to our energy consumption. Just because it’s cheap or we can produce it ourselves doesn’t mean we should waste it. Overall, our country is still heavily dependent on energy imports from abroad and every surplus kWh fed into the network contributes to the country’s self-sufficiency and reduces dependence on fossil fuels.  This means that’s important to take care to avoid the “rebound effect” increasing one’s own level of consumption when producing electricity oneself, thereby decreasing the benefits to the community. It would be unfortunate if the ability to generate one’s own renewable electricity was used to justify increased consumption. Renewable electricity remains a valuable resource, it is always advisable to ensure that energy is used in a responsible manner.

If you already have a photovoltaic power plant in operation and you would like to consume the electricity you produce yourself, please contact your network operator, who will propose you the necessary contractual arrangements. For some network operators, switching to self-consumption mode is possible through the network operator’s customer portal (this is for instance the case on the Creos portal: https://my.creos.net/s/login/?language=fr).

If you do not yet have a photovoltaic plant, contact an electrician for a quote and to carry out the installation. Ensure that the quote includes an adaptation of the electrical board, if such adaptation is necessary. Indeed, it is up to the electrician to assess the conformity of the existing electrical board or to have the network operator check that the minimum safety conditions are met.

It may be that installing a power generation plant will involve replacing the existing electrical board, even if it fully meets the needs of the existing installation. It is important to recognise that a power-generation plant that feeds into the network must meet a sufficient level of protection to ensure the required security for the lifetime of the power plant (i.e. for at least the next 25 years). This is an opportunity to bring the electrical installation up to the latest standards.

Once your project becomes concrete, your electrician will prepare a network connection application for you. The network operator will ask you to sign a contract for use of the network and will ask you to choose between the various options available to you (full injection, self-consumption, feed-in tariff contract, take-back contract to be concluded with a supplier).

Once the plant has been installed, the connection verified by the network operator and the meter installed, the respective supplier will apply for commissioning and the plant will be able to feed into the network.

Yes, not only can you generate your own electricity, but it is even encouraged, as long as it is generated from renewable sources.

However, this should be done under certain conditions which are explained below.

For photovoltaic power installations to be installed on the roof of a residential house, there are generally no particular constraints. However, a building permit or permission from the municipality may be required. Check with your local authority before starting your project. Restrictions may apply to listed buildings (cultural or historical heritage).

Other types of power installations are also possible (e.g. mini wind turbines), but are subject to more restrictive conditions due to possible harmful effects.

Generally, from a technical and economic point of view, it is not feasible to install a power installation on a house that will meet consumption needs throughout the year. Therefore, it is better to connect the installation to the power supply network so that you can inject electricity into the network when you are producing surplus electricity and withdraw electricity when there is insufficient production to cover your consumption.

Firstly, the network operator should be contacted to find out about any capacity restrictions in its electricity network. Contact your network operator, either yourself or through your electrician, to find out about available capacity. Note that the network operator must not refuse to connect a renewable electricity generation facility, but in cases where the network needs to be reinforced, you may be charged for the costs involved and the work may take time and delay your project.

Note also that injecting electricity into the network is only possible with a feed-in contract with the network operator or a purchasing agreement with a supplier of your choice. If there is no contract, you will not be authorised to inject electricity into the network. Indeed, any injection must be associated with a balance perimeter administered by a Balance Responsible Party (which is generally an electricity supplier).

You should therefore conclude:

1. a) either a feed-in contract with the network operator, whereby the remuneration is guaranteed on the basis of a regulated price for 15 years from the first injection. For more information on investment subsidies and regulated feed-in tariffs, please consult the Klima-Agence web pages (https://www.klima-agence.lu/fr/avantages-production-electricite)
2. b) or an electricity take-back contract which suppliers are free to offer. This is a traditional commercial contract whereby the supplier buys the electricity produced directly from the producer at a price freely discussed between the parties.

Option a) is only available for newly built power plants if they have not benefited from the 50% investment aid scheme introduced by the Grand-Ducal Regulation of 7 April 2022; while option b) is, in principle, always possible (i.e. also for existing power plants).

Option a) must be selected before the plant is commissioned. It is not possible to select this option after the plant has been commissioned or to return after having left it.

When installing a generation plant, you can opt for full injection or self-consumption. Self-consumption is always possible, regardless of the type of contract concluded.

In the case of self-consumption, the network operator will calculate the net values (corrected after deduction of self-consumed quantities) of injection and withdrawal from the public network for each quarter hour. Your supplier will therefore not bill you on the basis of your total consumption, but will use the “corrected” withdrawal data and the “corrected” injection data for billing.

Therefore the electricity that is consumed remains “local” and is not charged; it is not subject to any network charges, fees or taxes.

In general, but even more so in times of high energy market prices, in most cases it makes financial sense to install a PV plant and to shift your consumption to the production hours of the plant as much as possible, i.e. when the sun is shining.

In order to increase the share of self-consumed electricity, it is possible to add a local battery to store the excess energy produced, thereby increasing autonomy by storing the energy produced for later consumption, instead of feeding it into the network.

However, in order to become completely independent in the event of a power failure, one would need to install a high capacity battery that is able to cover power requirements for the envisaged period. This does not preclude the possibility for a system that can continue to meet needs even in the event of a power cut, within the limits of the quantities stored using the battery. However, the economic profitability of this type of installation must be assessed on a case-by-case basis. For more information on financial aid and subsidy schemes, visit the “Klima Agence” website www.klima-agence.lu.

The network operators’ technical connection conditions provide connection diagrams, as well as the necessary protective devices for the different cases. Technically, the connection is done in the same way, whether for total injection or for self-consumption.

There are a number of practices you can implement to save energy on a daily basis. Practical advice on how to save electricity and heat well can be found on the Klima-Agence websites. Furthermore, if you want to know how to save energy, reduce your energy costs or which measures are eligible for financial support from the state, you can call the free hotline provided by Klima-Agence on 8002 1190 or your supplier.

For more information, do not hesitate to contact Klima-Agence, which accompanies all those interested in finding out about solutions that correspond to their projects for sustainable living and mobility, thereby helping them to consume better and less. See the website for grants: https://www.klima-agence.lu/fr/klimabonus-aides

You can also visit the government’s portal, Guichet.lu, and consult the page about financial support for renovation projects and improving the energy performance of your home https://guichet.public.lu/fr/citoyens/logement/renovation-transformation/performances-energie.html.

The organisation Klima-Agence (www.klima-agence.lu), your supplier as well as other stakeholders in the sector, such as energy advisers and heating and electricity professionals can inform and advise you on energy efficiency matters. The information provided by www.oekotopten.lu may also be useful.