If you want to install photovoltaic modules on your roof, but don’t know how much energy they may be able to produce in a year, how do you find out?
You could use free online tools to do an estimate, or you could ask a local installer – who might use the same online tools that are available to you. One of these tools, the Photovoltaic Geographic Information System PVGIS, developed and maintained by the European Commission’s Joint Research Centre (JRC) is currently used by more than 15,000 visitors every day and processes nearly one billion data requests per year to perform such estimates.
It is available in English, French, German, Italian, and Spanish. And in just a few steps – selecting your location, refining your settings if required, then clicking ‘visualise results’ – you can do your own PV energy estimates.
But let me take you on a little journey in time to reveal how we arrived at this tool, starting when the first commercial PV modules became available in the 1980s. Back then, PV technology was so new that there were no agreed measurement protocols or standards available for measuring the conversion efficiency and electrical power output of these devices.
JRC scientists from the European Solar Test Installation (ESTI), a world-leading laboratory for the characterisation of PV devices, got to work and developed the first European standards both for the power measurement and the type approval of PV devices. This work laid the foundation for international standards that are still today instrumental in the success of PV as a global energy source. Yet, the power label of the PV module, which is part of the CE label on each PV module sold on the EU market, is not the same as the expected energy that the module could generate on your rooftop.
The reason is that the power rating is determined under laboratory test conditions with an irradiance of a standard light spectrum and 1000W per m² and a temperature of 25°C. The light spectrum and irradiance mimic direct sunlight that arrives on the earth’s surface under clear sky conditions around midday. Of course, you will only occasionally find these conditions on your rooftop throughout an entire year, and as a prosumer you are more interested in how much energy you will generate. Hence, you need to understand the expected energy output of a PV device under all the conditions that you will experience during a given year and location.
That is why JRC scientists of the ESTI laboratory led international efforts to develop an energy rating standard that establishes a measurement protocol for PV modules under various light and temperature conditions. This is then used as a basis to match the measured values with different climatic zones.
It is also the basis for a new label that the European Union is currently exploring for PV modules. The new label would provide information on the expected energy output of a given PV module for different climatic zones in Europe. As such it would enable prospective buyers of PV modules to compare different PV modules with each other so that they can make a well-informed choice.
The JRC scientists have then decided to combine their detailed laboratory data with climate data in the popular PVGIS tool, and make this available as a free online version for everyone. The tool basically applies the principles of the energy rating standard with a higher granularity as specific local conditions are considered, thanks to the use of high-resolution satellite and re-analysis datasets that provide European and worldwide coverage.
The main users of PVGIS are citizens, installers, project developers, researchers, professors and students. The tool is very flexible and supports, besides individual simulations, also bulk requests. This function enables larger feasibility studies, for example the potential of PV deployment on buildings or along highways and rail tracks, on water reservoirs, potential impacts of high PV shares on energy markets. They also allow the seamless integration of PVGIS into other tools.
In a recent study, JRC scientists have analysed the photovoltaic rooftop potential of all 271 million buildings in the EU. Here they made use of the PVGIS tool together with another exciting database that JRC scientists have developed and published free for everyone to use, the European Digital Building Stock Model.
In a massive number-crunching exercise, they have combined these two to establish a firstof-a-kind solar rooftop cadastre for the entire EU. It turns out that there is vast potential in the EU for rooftop PV. Of course, this is just the technical potential and many other factors need to be addressed before this potential can be fully leveraged, notably flexibility measures, grids, and energy storage, just to name a few.
The development and deployment of photovoltaics is a European success story. The laboratory and desktop research work of EU scientists helped establish the standards that are an important basis for the success of renewables and enabled the development of related digital tools which empower citizens, energy communities and businesses to actively shape the energy transition based on their own well-informed decisions and also support scenario work for further renewables deployment.
"In a recent study, JRC scientists have analysed the photovoltaic rooftop potential of all 271 million buildings in the EU."
Currently, JRC scientists are working on a complete modernisation of PVGIS that in the future will enable start-ups and scale-ups to develop their own tailor-made solutions, and allow other scientists to benefit from the know-how of the JRC scientists and ESTI laboratory. One thing is clear – there is still a lot of upside potential for renewables in Europe, and better access to data and tools can play a crucial role in turning this into a sustained success story for the EU.
This is just one example of how JRC scientists provide independent, evidencebased knowledge and science, supporting EU policies to positively impact society. Many other examples could be given, be it in the domains of energy, mobility, and climate, or practically all other policy files of the EU.
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