Photovoltaic self-consumption

The EU legislative framework facilitates the transition to a clean energy model, empowering European consumers to become fully active actors in the energy transition. This framework also sets two new targets for the EU for 2030, a binding renewable energy target, and an energy efficiency target, with a possible upward revision in 2023.

The European strategy identifies 3 pillars: citizen empowerment, renewable energies and energy efficiency. And it defines as essential policy the democratization of energy, that is, that the citizen can generate his own energy, store it and share or sell it to the electricity system.

What is self-consumption?

By self-consumption of electrical energy we mean the production of electricity for our own consumption. Law 24/2013, of 26 December, on the Electricity Sector, defines self-consumption, as a result of the amendment incorporated by Royal Decree-Law 15/2018, of 5 October, on urgent measures for the energy transition and the consumer protection, such as the consumption by one or more consumers of electricity from production facilities close to those of consumption and associated with them.

At the domestic level, self-consumption is mainly done through low-power photovoltaic solar energy installations. Traditional electricity generation is characterized by following a centralized, unidirectional generation scheme with few control measures over the performance of demand.

There are currently technically and economically viable solutions that allow a change from this model to another of distributed electricity generation, where any consumer can generate their own electricity, produced mostly with small power installations and through the use of local renewable sources, mainly photovoltaic solar energy.

In this way, self-consumption facilities can cover all or part of the electricity consumption of the home, the neighborhood, the building or any consumer center through its own generation system.

When the generation system does not produce enough energy, electricity can continue to be consumed through the electricity grid and, in certain cases, when production exceeds demand, it is possible to pour the surplus into the grid.

Types of facilities

Individual or collective

  Self-consumption facilities can be individual or collective.

In the individual ones, the generation installation is associated with a single house, for example a photovoltaic installation on the roof of a single-family house that feeds only the house's own consumption.

The regulations also allow more than one home to be associated with the same generation facility. They are the facilities of collective self-consumption. It would be for example the case of an installation in a neighborhood community, where all or some homes share the photovoltaic installation located on the roof of the building. This facility can also power common services, such as the elevator or stair lighting.

Likewise, the regulations allow to participate in an installation that does not have to be necessarily located and connected to the same building. In this way, the electricity produced by a “nearby” installation can be consumed, as long as the point of consumption and the generation installation meet any of these three requirements:

- Be located in the same cadastral reference (up to the first 14 digits).

- Be connected to the low voltage network of the same transformation center.

- Be connected to the low voltage network at a distance of up to 500 meters.

Self-consumption electricity generating installations can be of two types:

The regulations also differentiate between self-consumption facilities without surpluses or self-consumption with surpluses.

No surplus. When installed physical devices called anti-spill prevent the injection of any excess energy into the transmission or distribution network. In this case there will be a single type of subject from those provided for in Article 6 (LSE), which will be the consumer subject.

Only individual and collective installations connected to the internal consumption network can be self-consumption installations without surpluses, not those that self-consume the electricity produced in a “nearby” building.

It should be noted that if an anti-spill system is installed, surplus electricity is lost and therefore cannot be given value, as it cannot be injected into the grid. This fact is relevant if we take into account that normally the photovoltaic self-consumption installations of the domestic sector have surpluses, since very often there is no simultaneity between the production of electricity, during the hours of sun, and the consumption. .

With surpluses. When the generation facilities can, in addition to supplying energy for self-consumption, inject surplus energy into the transmission and distribution networks. In these cases there will be two types of subjects than those provided for in Article 6 (LSE), the consumer subject and the producer.

In facilities with surpluses, in addition to supplying energy for own consumption, when more electricity is being produced than is needed, surplus energy can be injected into the electricity distribution network.

Battery installation

It is also possible to incorporate accumulators (batteries) that allow us to store electricity and use it at times when we do not have our own generation (for example, at night in the case of a photovoltaic installation) or when we deem it convenient. We can also store this electrical energy from our self-consumption system in the batteries of the electric vehicle.

They are recommended if you want to achieve a high level of self-consumption and self-sufficiency. However, given the current high cost of batteries from an economic point of view, it is necessary to analyze their suitability on a case-by-case basis and compare it with the cost of instant self-consumption (without batteries).

Administrative processing:

The administrative processing of the installation requires procedures at municipal and Generalitat level, as well as procedures with the distribution company, depending on the power and type of installation.

Urban Procedure (Prior communication) - City Council

Procedure for access and connection to the network (exempt installations of up to 15 kW on urban land with endowments and installations without surpluses) at the Distribution Electric Company.

Registration in the Register of Self-Consumption of Catalonia - Generalitat

Permissions, step by step

Before starting to carry out the installation, the works permit must be processed at the town hall where the installation is located. In relation to the building permit, the Town Planning Act stipulates that photovoltaic solar installations that do not exceed one meter in height from the flat roof or that are placed above the sloping roof, will be subject to to the prior communication regime, with some exceptions. Each city council decides what documentation must be provided in the procedure.

Self-consumption installations without surpluses (of any power) and self-consumption installations with surpluses of power equal to or less than 15 kW, when they are located on urbanized land that has the endowments and services required by the urban planning legislation, are exempt from obtaining permits for access and connection to the electricity grid. Therefore, in these cases, no permission is required from the electricity distribution company to run the installation.

In the case of a surplus installation with a power greater than 15 kW, as may be the case for a collective installation, it will be necessary to request access and connection permits from the distribution company. .

Finally, it is necessary to legalize the installation before the Generalitat, with the appropriate procedure depending on the power of the installation, the generation of surpluses and their possible compensation. It should be borne in mind that for installations with a power of up to 100 kW, no prior administrative authorization is required, and this legalization process is easy to do once the installation has been carried out.

Once the legalization process has been completed, the Generalitat automatically registers the installation in the Self-Consumption Register of Catalonia.

The procedures related to self-consumption before the Generalitat de Catalunya are carried out through the Canal Empresa Tràmits Autoconsum channel.

Distribution of energy in collective facilities

How is energy distributed in collective facilities?

The people associated with a collective self-consumption installation must agree on the system for distributing the energy produced by the installation.

The distribution criterion will be the one that the associates consider most opportune, such as distributing the energy produced in proportion to the investment that each one has made. The only condition is that the sum of all the distribution coefficients is the unit and that these are constant.

These distribution conditions must be reflected in an “Energy Distribution Agreement”, signed by all persons associated with the installation. They must communicate the agreement individually to the distribution company, directly or through the marketing company.

The regulations propose a default distribution criterion, based on the power contracted for its supply by each associated person.

In collective installations it is mandatory to put a meter that measures the energy produced by the self-consumption installation. The generation meter measures the energy produced, while the individual meters we already have measure the energy consumed by each home. The marketing company must then deduct from the bill of each associated person its share, in accordance with the corresponding distribution coefficient, of the kWh of electricity produced by the self-consumption installation. If you have more kWh than you have consumed, you can compensate them on your electricity bill, if you resort to the simplified compensation mechanism.

What is the useful life of the installation? Does it require maintenance?

Photovoltaic panels suffer a small degradation throughout their useful life which is reflected in a slight loss of performance. Panel factories usually guarantee that their performance will not be reduced below a certain level for a certain period of time. They usually guarantee that after 25 years of operation the panels will have at least 80% of the original performance.

Battery life

If you have batteries, their useful life is measured in cycles. A cycle is a complete charge-discharge process (up to the recommended discharge depth). Its useful life depends on its use, but it will generally be shorter than that of photovoltaic panels and, therefore, it is necessary to provide for its replacement during the useful life of the installation.

Maintenance

  Self-consumption photovoltaic installations require little maintenance. With the correct use and care of the installation, its life is extended and its production is optimized. For this reason, it is advisable to hire regular maintenance from a specialized company or professional. Usually, an annual check is enough to ensure its proper condition and operation.

Finally, it is advisable to monitor the installation periodically (weekly or monthly) to verify that it is working properly. This tracking can be easily done through computer programs provided by the inverter manufacturer.