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Solar Energy

The sun is a constant source of energy. This energy reaches the Earth in the form of radiation, and only 3/4 of it actually penetrates the atmosphere. To be exploited, this energy has to be captured first.

Depending on the use that will be made of this energy, different capture systems are used, and the best use depends on the amount of radiation received, which varies according to the season of the year and the time of day.

Solar energy allows different uses, such as the generation of electricity through photovoltaic modules, thermal exploitation and passive gain.


Solar power, in its different modalities, helps to reduce the use of conventional energies to obtain heat and electricity.
Therefore, solar energy is:

  • Renewable
  • Clean as it does not pollute
  • Silent
  • Integrated into buildings, with no visual impact


Solar electric energy is produced through the photovoltaic effect, i.e. when the sun's rays hit solar cells voltage is produced.

Solar cells are usually made of silicon. Silicon is a semiconductor that can generate voltage through the effect of solar radiation. This means that electricity is produced by the physical characteristics of the material used - silicon - that reacts to sunlight.

These cells are grouped together to create a solar module. The combined modules make up a solar panel.

Photovoltaic solar plants are basically of two types: isolated installations that are mainly used for pumping, signalling, communication and rural electrification, and others that are grid connected for the sale of electric power and auto-consumption.

Energy production depends on sunlight, and this energy can either be consumed at the time it is produced or it can be stored for later use:

Isolated photovoltaic systems

An isolated photovoltaic systems where access to the grid is difficult, the storage system used to guarantee electricity supplies is based on batteries.

  1. Photovoltaic modules
  2. A regulator to avoid overloads
  3. After a working life of around 10 years, the collection of these batteries should be controlled so that they can be correctly treated and recycled.

Grid connection

In this case, photovoltaic systems are connected to the general grid. The energy generated, depending on the form of connection, can be for auto-consumption or fed into the grid. The use of batteries is not necessary because the installation is grid connected. Nevertheless, it is possible to place batteries in cases of auto-consumption. These are charged when there is sunlight and they return the stored energy at times when the grid requires supply.

  1. Photovoltaic modules
  2. Inverter
  3. Power grid
  4. Consumption of the building (AC)
  5. System for grid connection

Applicable legislation

Spanish Royal Decree (RD) 244/2019 of 5 april, by which the administrative, technical and economic conditions of the self-consumption of electrical energy are regulated.

RD-ley 15/2018 of 5 october, of urgent measures for energy transition and consumer protection.

RD 900/2015 of 9 October 2015, regulating the administrative, technical and economic conditions of the modalities of supply of electricity under auto-consumption and production with auto consumption.
* Consolidated text:.- The consolidated text of RD 900/2015 incorporates the changes introduced by Sentence 68/2017 of 25 May 2017

RD 413/2014 of 6 June 2014, regulating production activity of electricity from renewable energy sources, cogeneration and waste materials.

Ley 24/2013, of 26 December, on the Electric Power Sector.

RD 1699/2011 of 18 November 2011, regulating the grid connection of small-scale electricity production facilities.

RD 1110/2007 of 24 August 2007, approving the unified Regulation on metering points in the electric power system.

RD 1955/2000, of 1 December, regulating the activities of transport, distribution, marketing, supply and authorization procedures for electric power facilities.

Order ETU/1282/2017 of 22 December 2017, establishing access tolls for electric power for 2018.

Sentence of the Constitutional Court cancelling out section 3 of article 4 of RD 900/2015,which establishes that “In no case may a generator connect to the internal grid of several consumers” and article 19, 20, 21 and 22 of said Royal Decree, related to the register of auto-consumption.

The content of the self-consumption section of the EVE website is being updated to the new regulatory framework established in RD 244/2019 of April 5, which regulates the administrative, technical and economic conditions of the self-consumption of electric energy.


Through these objectives, on one hand the aim is to increase consumption of local renewable energies, and on the other, foster the development of the industrial sector in the Basque Autonomous Community.

Indicator 2016 Objetctive 2020
Installed photovoltaic solar capacity (MW) 26,7 55
Use of photovoltaic solar energy (ktoe/year) 2,6 12