Definitions and concepts
- Energy self-consumption: Self-consumption* is understood as making use of electrical energy generated by means of a photovoltaic installation supplying a building or a home. This self-consumption can be done instantaneously (within a given hour) and what is not consumed can be stored in batteries, sent to the grid and sold or stored in batteries. *Self-consumption is electricity production for own consumption. The Electricity Sector Act, 24/2013 of 26 December, defines self-consumption as the consumption of electrical energy that comes from consumer grid-connected power generation facilities or via a direct power line linked to a consumer. The self-consumption installations may be stand-alone (not physically connected to any electricity company grid) or connected to the grid. Self-consumption installations connected to the grid are legal and any consumer can generate their own electricity if they want to. Self-consumption installations can include batteries. These serve to store energy that comes from solar panels when no energy is being consumed, so it can be used at other times when there is a demand and not enough is being produced at that moment.
- Individual self-consumption: When we speak about individual self-consumption, we are referring to those installations that are connected to a single consumption point, regardless of whether this is for the consumption of a home or for a stairway of neighbours with a single supply point (e.g. for communal installations, such as lifts or stairway lighting). In any event, if individual self-consumption is practised, the energy used will be from a single supply point.
- Shared self-consumption: This refers to a generating installation that is connected to various consumers. It can therefore supply various communal uses on the stairway, various homes or can become a local energy community. Nowadays, sharing consumption is carried out using static distribution coefficients, and in the near future it is planned to approve sharing through dynamic distribution coefficients.
- Distribution coefficients: When distributing the energy generated by a collective renewable-energy installation among the members of an energy community, there are a number of possibilities. Taking into consideration that the generation does not instantaneously coincide with the demand (e.g. a photovoltaic installation will generate during the day, when some homes may be empty), it is interesting to analyse consumption in order to determine the most appropriate strategy for making the best instantaneous use of the energy. Nowadays, distribution among facilities, homes or consumers can be done via a static distribution coefficient: the percentage of generated energy distributed to each member of the community is previously agreed, regardless of whether a particular member consumes that amount every day of the week or year. This means that if, on a certain day, a user does not instantly consume the energy generated by the installation, it will be discharged into the grid, with the option of either selling it or being compensated for it. There are now plans to introduce what is known as dynamic distribution. The idea is for the energy to be distributed to each member according to their demand for energy, thereby maximising self-consumption by the members of the community. This option has not yet been regulated by the Spanish government, and the information given here is what has been compiled or explained in some prior, unapproved draft, and therefore subject to possible changes.
- Local energy community: There is still no clear official definition of what a local energy community is but, in line with European regulations, a local energy community is a community of natural persons, SMEs or local administrations located near a renewable-energy project, which they own. All of them benefit from the energy generated by this installation. The community must be based on the open, voluntary participation of its members, and its main objectives must be environmental, economic or social benefits for its partners and members or the area around the project, rather than financial benefits.
- Photovoltaic pergola: a pergola is an architectural structure in a public area that is habitually used for shade and consists of a aisle flanked by vertical columns that support longitudinal beams or a roof that span the columns on either side. A photovoltaic pergola uses this structure to construct a photovoltaic solar energy installation.
- Photovoltaic dividing wall: • a photovoltaic installation located on a dividing wall. Dividing walls are anonymous and divide properties. Although they play no role in the building’s exterior appearance, they can end up exposed to public view, following urban-planning changes, in a permanently provisional state. When that happens, it leads to a discontinuity in the landscape, a break in the urban fabric which then poses serious building and habitability problems for local residents. With the aim of integrating Barcelona’s urban discontinuities into the urban fabric surrounding them, the Urban Landscape Institute foments the rehabilitation of dividing walls with architectural integration projects that try to give meaning to these spaces, providing cultural and social identity to places that have lost them. A photovoltaic installation is a good way of giving these features a new use.
- Cogeneration: the combined production of electricity (or mechanical energy) and heat energy from a primary energy source, such as natural gas, diesel or fuel oil, which is later reused.
- Geothermal power: energy that comes from harnessing the thermal energy of the subsoil and geothermal deposits.
- Hydropower: energy that comes from harnessing the potential energy of falling water or the kinetic energy of fast-flowing water.
- Hydroelectric power: electrical energy produced by harnessing the potential or kinetic energy of water.
- Clean energy: energy which can be obtained and used without generating waste, has moderate to minimal environmental impact and produces no chemical or noise pollution. ◦ NB: examples are solar power, wind power and geothermal power.
- Nuclear power: energy obtained from atomic nuclear fusion or fission.
- Renewable energy: energy obtained from inexhaustible or renewable sources. ◦ NB: for example, the energy obtained from charcoal and wood.
- Solar power: radiant energy emitted by the sun in the form of electromagnetic waves.
- Thermal power: heat energy produced by burning coal, oil, natural gas and other fuels in thermal machines.
- Photovoltaic solar energy: electricity obtained from sunlight. The sun’s rays hit solar panels made up of a collection of small silicon cells designed to capture solar radiation and turn it into electricity.
- Solar thermal energy: This is the energy that is directly obtained when harnessing the heat of the sun’s rays for heating up another fluid. It is based on solar collectors or panels that are struck by the sun’s rays, and the heat collected is used for producing hot water for human consumption.
- Small-scale wind power: This harnesses the kinetic energy of the wind and turns it into electricity or mechanical energy. Energy is generated from aerogenerators moved by the wind.
Energy and environment
- Greening the network: Generating green energy and injecting it into the grid makes it possible to reduce greenhouse-gas (GHG) emissions associated with energy consumption. Electrical energy produced by fossil fuels and non-renewable resources are currently the main sources for the grid (at around 85%). Any contribution we can make along these lines enables us to improve the electricity system and reduce emissions. This is known as greening the grid.
- Energy certificate: an energy-rating document that officially identifies and certifies the power consumption and energy efficiency of certain products, such as housing and electrical appliances. The rating is based on a scale of 7 letters, where A identifies maximum energy efficiency and G the least efficiency. ◦ NB: energy certificates are issued by an independent third party.
- Greenhouse effect: the phenomenon of atmospheric warming, caused by the atmosphere being transparent to solar radiation and its capacity for absorbing the Earth’s infra-red radiation.
- Energy efficiency: the degree to which an optimum relationship is achieved between the resources used in energy management and the results obtained.
- Greenhouse gas emissions: the total mass of greenhouse gases released into the atmosphere in a specific period.
- Emission savings [gCO2eq]. Estimates of greenhouse-gas emission savings have been made by taking into account that each new PV generation facility installed in the city displaces kWh produced by a combined-cycle power generation plant. Therefore, the greenhouse-gas emission saving is considered to be 360 g of CO2 equivalent per kWh produced.
- Tones de CO2 equivalent: the impact of greenhouse gas (GHG) emissions is often measured in tonnes of CO2 equivalent, which corresponds to the tonnes of CO2 that would generate the same greenhouse effect. This makes it possible to compare the emissions of various GHGs, as some of them have a much higher potential effect than others, and smaller quantities can make a greater contribution to global warming.
- Thermal envelope of a building: also known as the skin of a building, is the set of structures that separate the habitable areas of the building from the exterior environment (air, land or another building) or from non-habitable areas that are in contact with the exterior environment (façades, rooftops, dividing walls, walls in contact with the ground, etc.). It is essential for them to be well insulated and to have proper solar protection, in order to ensure comfort and low energy consumption in the building.
- Energy label: a voluntary rating system that officially identifies and certifies the energy consumption and efficiency of certain products. ◦ NB: energy labels are awarded by an independent third party.
- Greenhouse gas (GHG): the natural or anthropogenic gas in the atmosphere that absorbs and emits radiation on specific wavelengths of the infra-red radiation spectrum emitted by the Earth’s surface, the atmosphere and the clouds. GHGs include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulphur hexafluoride (SF6) and nitrogen trifluoride (NF3).
- Emission inventory:: the calculation and location of emissions discharged into the atmosphere in a specific area.
- LED: the acronym for Light Emitting Diode. LED lights are currently the most efficient lighting on the market. They consume less energy and last much longer than other lighting technologies.
- Clean production: a type of industrial production that minimises its environmental impact by means of careful resource management, proper product use and design, waste reduction and management, the use of clean technology and so on.
- Energy recovery: utilising waste to produce energy as an alternative to other sources.
- Interior connection: n individual self-consumption installations, the connection between the generating installation and our network has to be linked to the dwelling’s interior, i.e. from the electricity meter to the interior of our home. This system is known as interior connection.
- Electric battery or accumulators: a group of electric accumulators connected in series or in parallel. A photovoltaic generating installation can always be combined with batteries. Including batteries makes it possible to store a certain amount of energy when there is no power consumption but there are solar resources, with the aim of making use of this stored energy at times of high demand where there is insufficient instantaneous photovoltaic generation.
- Solar collector: a device used to collect incident solar radiation and turn it into thermal energy for domestic and industrial uses.
- Connection to the electricity grid: energy produced by a photovoltaic installation can be introduced directly into the conventional power grid. That is what we call a grid-connected PV power installation. This type of installation enables us to improve the energy mix, introduce a larger amount of energy from renewable sources and move away from energy that comes from fossil fuels.
- GIOS: the acronym in Catalan for Gestor Integral de l’Ordenança Solar (Integral Solar By-law Manager), online software developed by Barcelona City Council to simplify procedures for obtaining the municipal licences required for installing thermal and photovoltaic solar energy facilities, in accordance with the procedure set out in the Barcelona Solar By-law. At present, the GIOS is only used for procedures that were initiated with the Manager and that are awaiting completion. The documentation regarding compliance with Section 8 of the OMA for new construction-permit applications is processed together with all the other documents associated with processing the major-construction permit for the building concerned.
- Solar panel: a device with a large surface area for capturing solar radiation, which is converted into heat (solar thermal energy) or electricity (photovoltaic solar energy) and can be used for domestic or industrial purposes.
- Solar radiation: the electromagnetic radiation emitted by the sun, 90% of which has a spectrum that falls between 0.25 and 5 µm, approximately.
- Surface area: in a solar installation, it is the surface area covered by the panels, which capture solar energy and transform it into thermal power or electricity.
- Retail electricity company: the company that buys the energy on the electricity market and sells it to the end consumer.
- Peer-to-peer lending/socialised financing: his enables citizens to lend money and gradually get it back with interest. Peer-to-peer lending is an innovative form of collective loan where, in contrast to crowdfunding, the money contributed is returned.
- Electricity distributor: the company responsible for distributing electricity from high-voltage networks to its various supply points. *They are assigned national territorial zones, so that the electricity distributor for each user depends on their geographical location and they are independent from the company the user contracts their electricity from. Furthermore, electricity distributors are responsible for the maintenance of the power distribution grid, the installation and maintenance of meters, activating services for new supplies and meter reading, as well as repairing power outages, among other functions.
- Energy rights: the rights that establish energy as a commodity of prime necessity, with equal and universal access at a fair price, in order to ensure a decent life for everyone.
- Energy sovereignty: energy sovereignty is the right of aware individuals, communities and urban settlements to make their own decisions about the generation, distribution and consumption of energy, so that this is appropriate for their ecological, social, economical and cultural circumstances, provided that it has no negative effects for third parties.
- Basic supplies guaranteed: electricity, water and gas are a basic right which everyone enjoys guaranteed access to. This is stated in the Act, which bans companies from cutting off supplies to vulnerable households and obliges them to maintain their services for as long as the situation of financial difficulties lasts.
- Watt: unit of power. The quantity of energy (in joules) that is generated, used or converted in 1 second. 1 watt = 1 joule/second.
- Kilowatt (kW): 1.000 watts
- Megawatt (MW): 1.000.000 watts
- Gigawatt (GW): 1.000.000.000 watts
- Wh: The energy generated by the power of 1 W for 1 hour.
- kWh: 1.000 Wh.
- kWh/any: the energy generated/consumed in a year, measured in kWh.
- kWp: peak (or maximum) power that a photovoltaic installation can generate, measured in kW.
- kWn: nominal power or rated capacity, measured in kW. In a photovoltaic installation, this refers to the power of the photovoltaic inverter, responsible for converting the generated energy from direct to alternating current. The nominal power is what marks the generating limit of the installation.
How are generation equivalent households calculated in a photovoltaic installation?
How much energy does a photovoltaic panel produce?
The energy produced by a photovoltaic panel mainly depends on the power of the panel and the solar radiation it receives during the day. The incident radiation changes throughout the day and with the seasons and is affected by the panel’s orientation and inclination, as well as by other factors, such as the environmental temperature and the age of the panel, as its efficiency (the capacity for turning incident solar radiation into electricity) declines over time. On average, for Barcelona city, it is estimated that a typical, recently-installed panel could produce between 1,000 and 1,300 kWh/kW/year, depending, as mentioned earlier, on where it has been installed (hours of sunlight) and according to its inclination and orientation.
With regard to Barcelona’s municipal photovoltaic installations, they produce a lot of energy, and on average, we can say that for every kW of installed capacity, they produce around 1,200 to 1,250 kWh of energy a year in the case of buildings, and around 1,000 to 1,100 kWh a year in the case of public spaces. The incidence is lower in public spaces, because there is more shade and the installation is usually more horizontal than it would be on a roof.
How is the power of a photovoltaic installation calculated [kW]?
The power of a panel refers to the maximum amount that it can generate at any given time. Apart from the number of photovoltaic modules, there are other specific factors that alter the maximum power an installation will generate, such as the radiation that reaches it, the orientation of the panels, the condition they are in and so on. Photovoltaic installations use two power ratings, peak power [kWp] and nominal power [kWn]. Nominal refers to the power of the equipment and peak to the total power of the collector modules.
What does having cleaner energy production mean?
The continuous application of an environmental prevention strategy that is integrated into products and processes in order to reduce the risks that might affect people and the environment.
NB: in production processes, the concept of cleaner production includes conserving energy and raw materials, and reducing the amount and toxicity of waste and emissions. The UNEP (United Nations Environment Programme) often uses this concept to highlight that work in this field is continually under way and advancing.
What are centralised urban air-conditioning networks?
These are heating and cooling systems where the generation of heat and cold are centralised in a thermal power plant, which supplies heat and cold to all the buildings connected to it (offices, residential buildings, commercial establishments, hotels, etc.). In order to do this, the thermal power plant heats or cools water, which is then supplied through a distribution network, usually underground, to the thermal transmission substations in the buildings, where the heat or cold is transferred to the building’s own distribution network, in order to reach the end users.
What is a voluntary solar installation?
In certain circumstances, the Barcelona’s Environmental By-Law, the Eco-efficiency Decree, and the Technical Building Code make it mandatory to have systems to exploit solar energy or other technologies in order to produce hot water for human consumption and electricity, in newly designed or constructed buildings or those being renovated or converted, or undergoing a complete change of use, etc.
Therefore, a voluntary solar installation is understood to be an installation that is not mandatory according to current regulations and legislation.
How is energy production regulated in Barcelona?
Section 8, on Solar Energy, of the Barcelona Environment By-law (OMA), published in the BOPB, 2 May 2011 regulates the obligation of introducing systems for exploiting solar energy in order to produce hot water for human consumption and electricity, in newly designed or constructed buildings or those being renovated or converted, or undergoing a complete change of use. Section 8 of the OMA includes what was previously Barcelona’s Solar Energy By-law.
What criteria does Barcelona use for the architectural and landscaping integration of solar energy?
The criteria for the architectural and landscaping integration of solar energy are orientated towards choosing solutions that integrate well with the construction characteristics of the building and the urban landscape in the immediate surroundings of the solar collectors (thermal or photovoltaic).
These criteria depend on a series of factors that are basically concerned with the construction characteristics of the building (architectural) and the landscape context of the urban area immediately around the site (urban planning). They make it possible to comply with energy requirements while preserving the building’s architectural characteristics and the immediate area’s urban-planning as much as possible.
A guide to the application of these criteria can be found here.
How is construction work carried out in Barcelona classified, and what types of permits and licences are required?
Construction work in the municipality of Barcelona is classified into major and minor construction work (the latter is also subdivided into three types: I, II and III). Operations considered to be major construction work are defined in Article 3.2 of the regulatory By-law for municipal intervention procedures in construction work (ORPIMO in Catalan). The applicable intervention regime is a PERMIT.
Type I minor construction work is defined in Article 3.3 and the applicable regime is that of a DEFERRED COMMUNICATION, regulated by Article 49 of the ORPIMO.
Type II minor construction work is defined in Article 3.4 and the applicable regime is that of an IMMEDIATE COMMUNICATION, regulated by Article 50.
Type III minor construction work is defined in Article 3.5 and the applicable regime is that of communication without presentation of any documents, known as KNOWLEDGE, regulated by Article 52.
PERMIT REGIME: by which means the City Council, after analysing the documents and project presented by the interested party and verifying that they conform with the applicable regulations, makes a resolution on the appropriateness of awarding the permit.
COMMUNICATION REGIME: whereby the presentation of the project and the required documents to the City Council entitles the interested party to carry out the construction work or effect the initial occupation of the building, unless the City Council, within the established time limits, notifies them that the project does not comply with applicable regulations or that another intervention regime must be followed.
DEFERRED: The interested party may begin the construction work if, within a period of one month, they do not receive any notification from the City Council regarding their communication, and once they have paid the corresponding rates.
IMMEDIATE: The interested party may begin the construction work the day after presenting the documents, once they have paid the corresponding rates.
KNOWLEDGE REGIME: by which means the interested party informs the City Council about the construction work they intend to carry out, without providing any documents, and they may begin the day after presenting the communication at the municipal registry.
What is energy compensation and who is entitled to it?
Surplus energy is the electricity generated by the solar photovoltaic panels that is not consumed instantaneously (e.g. if it is generated when we are not at home). Currently, this surplus energy can be compensated and this may be received by renewable-energy installations with an installed capacity equal to or less than 100 kW.
In our homes, the meter will account for this energy in the following way:
The balance between the generated and consumed energy is not completely instantaneous, but is currently carried out in 1-hour periods. This makes it possible to calculate the net balance between the energy generated and discharged into the grid during a 1-hour period and the total amount of energy consumed during that period.
If, during a 1-hour period, more energy is generated than consumed, the difference is compensated by means of a compensation mechanism. The compensation mechanism works in such a way that the energy discharged into the grid will be discounted from the electricity bill, at an established price, and from the energy quoted in the bill for the subsequent billing period. If there is not enough energy to effectuate this compensation, it cannot be used. In the case of homes and small installations, this is a highly recommendable option, because it is possible to make the best possible use of the energy without the need for any market representative or complementary figure: the compensation is carried out automatically in the electricity bill.
Beyond the generation mechanisms, there is also the possibility of selling the surplus. This mechanism means that the generated energy that has not been consumed (in a 1-hour period) can be sold to the electricity retailer at a previously established price. This sale has a series of associated taxes that are not applicable in the case of compensation, and will not be limited to the total energy required during the same billing period. In order to make this energy sale, a market representative is required, as a consumer cannot carry out the sale unless they are registered as such.
The retail company usually offers this representation service.
Is there really a ‘sun tax’?
Royal Decree 244/2019, regulating the administrative, technical and economic conditions for the self-consumption of electrical energy, was approved in April 2019.
RD 244/2019 definitively eliminates the tolls and charges on renewable energy, regardless of its power or whether there are batteries. This decree includes what has already been established in various directives published by the European Commission, and offers more mechanisms to favour proactive consumers, such as facilitating self-consumption with compensation for surplus or shared self-consumption. The proactive consumer, or prosumer, is a figure recognised in the ‘Energy Efficiency Directive Winter package 2016’ (https://ec.europa.eu/energy/en/content/energy-efficiency-directive-winter-package-2016). It must be remembered that, although the former RD 900/2011 established the possibility of introducing electricity tax charges, there is no evidence that any installation ever paid the famous ‘sun tax’.
What does ‘100% renewable energy certified by the CNMC’ mean?
When we contract green energy (from a renewable source) the National Commission for Markets and Competition (CNMC in Catalan) certifies that the energy we receive is really green.
In reality, we cannot guarantee that the electrons that reach our home actually come from renewable-energy plants. What the CNMC really does is to guarantee that the electricity grid has injected a certain quantity of energy supplied from renewable sources that is equivalent to what we have consumed.