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What is collective self-consumption?

Last updated on 3 May 2019

Rather than buying electricity from the grid, why not buy back surplus solar energy produced by a neighbour's solar panels? This is the concept of collective self-consumption.

Owners of solar panels are not currently allowed to sell surplus electricity to their neighbours. But the idea is slowly gaining ground...

What is self-consumption?

When you have solar panels on your private home, it is more cost-effective to consume your own electricity. This means using your own electricity directly rather than injecting it into the grid.

So, when the panels are running at full capacity, it's better to take the opportunity to run a washing machine: it is more ecological and also better financially than buying any electricity you need from the grid. And this will be even more the case when the 'compensation' principle (meter running backwards) ends.

Sharing electricity between neighbours

Collective self-consumption is based on the same principle, applied at neighbourhood, district or street level. This, of course, involves photovoltaic systems of a certain power producing surplus electricity.

Be careful not to confuse it with micro-grid islands operating in a closed circuit, independently of the national grid. Here, the idea is to stay connected to the grid to draw electricity from it that cannot be supplied by the panels and continue to inject any surplus production into it.

Specific examples  : 

Taking advantage of a powerful photovoltaic system nearby

Imagine a school that has a large number of solar panels.
During the school holidays, especially in July and August, and at weekends, the electricity produced is not being consumed.

It can then be supplied to neighbours at a very attractive price for both parties.

Creating a cooperative between neighbours

One can easily imagine that neighbours might get together in a cooperative to invest in a large photovoltaic system, each according to their means. This is already the case in blocks of flats.

But here the solar panels would be installed not on each individual roof, but on a large building in the neighbourhood with an available roof whose owner is interested in taking part.

Why is it worth sharing electricity via the public grid?

  • To buy/resell energy at a good price for both parties.
  • To make the most of renewable energies with naturally fluctuating prices when they become available.
  • To better balance the network, as balancing producer-consumer injections into the network is complex to manage.
  • To optimise the existing network infrastructure rather than building new lines/power plants.
  • To promote the installation of decentralised green production systems and maximise their use.

The elements required to develop collective self-consumption

1. Legislation

Legislation currently imposes a series of technical standards and rules for those who want to become an electricity producer and supplier.

Fortunately, the country's various regional regulations are evolving to allow the exchanges of electricity and money required for electricity sharing, but several issues still need to be resolved.

2. The limits of the electricity grid

Sharing local production collectively is only possible for buildings whose electrical installation is connected to the same low voltage sub-station. This limits the possibilities.

3. The question of the legal form

Collective consumer-producer customers must be represented by a legal entity (company, association, etc.) which will be the only point of contact for the distribution network operator (Sibelga in Brussels). Its main task will be to organise the customer community.

This legal entity will also have to take care of cash flows (issuing and receiving invoice payments).

4. The issue of monitoring consumption

To be able to accurately track the amount of electricity consumed from the national grid and that coming from any neighbouring producer, accurate metering data will be required. This will only be possible if each customer has a smart meter – the only type capable of managing this complexity.

Beyond the technical side, we can also ask ourselves who will process this confidential consumption data? From a legal point of view, the distribution system operator (Sibelga in Brussels) is well placed to act as a neutral, independent "trusted third party”, as it has no financial interest in the transaction.

5. The issue of tariffs for the use of the low-voltage network

To share locally produced energy, local customers must use the public low voltage grid. It will therefore be necessary to work out how to pay for this usage, just as is already the case for a conventional electricity supply, but at a lower price, given that only a small portion of the grid has been used.

The market regulator (Brugel in Brussels) will have to agree to allow special tariffs, as electricity prices are regulated by the authorities.

First pilot projects in the EU in 2020

The European Union promotes the principle of 'local energy communities'. Collective self-consumption is one way to create a local community in a virtual and flexible way: each customer connected to the same low-voltage sub-station could easily join or leave the community.

In several EU countries, including Belgium, pilot projects are being studied. The first should be launched in 2020.

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