Understanding PVGIS: The tool that revolutionized solar planning

When I started working in the photovoltaic sector about fifteen years ago, estimating the solar potential of a site was almost like alchemy. We used rough weather data, complex manual calculations, and a good dose of intuition. The arrival of PVGIS changed everything, transforming an uncertain process into a precise science accessible to all. Today, I can't imagine designing a solar project without this indispensable tool for both professionals and curious individuals alike.

The origins of PVGIS: a European story of innovation

PVGIS, or Photovoltaic Geographical Information System, was born from an ambitious vision within the Joint Research Centre (JRC) of the European Commission. In the 2000s, as solar energy was just beginning to emerge as a credible alternative, a team of European researchers tackled a significant challenge: democratizing access to high-precision solar data.

"Our goal was to create a tool that would allow anyone, from researchers to citizens, to evaluate the solar potential of any location in Europe," Thomas, one of the engineers who participated in the first versions of PVGIS, recently told me. "At the time, this data was jealously guarded by a few institutions or specialized companies."

What started as a European project gradually expanded to cover Africa, then Asia, and eventually the entire world. Today, PVGIS exists in two complementary versions: the free institutional version (PVGIS 5.3) maintained by the JRC, and the advanced commercial version (PVGIS24) which enriches the experience with additional features and a modernized interface.

Decoding PVGIS: much more than a simple solar calculator

To understand the essence of PVGIS, one must go beyond its technical definition. Certainly, it is a geographic information system specialized in photovoltaics, but that description does not do justice to its true nature.

An unmatched climatic database

At the heart of PVGIS lies a massive compilation of solar irradiation data, collected over several decades and constantly refined. Unlike the regional approximations used by other tools, PVGIS incorporates subtle local variations that can make all the difference.

During a project in the Swiss Alps, I was struck by PVGIS's ability to capture valley microclimates. Two sites only 3 kilometers apart had significantly different irradiation profiles due to the valley's orientation and shadows cast by surrounding mountains. This precision enabled optimal placement and avoided a miscalculation that could have jeopardized the project's profitability.

A sophisticated photovoltaic simulation engine

PVGIS doesn't just provide raw sunlight data. It integrates advanced models that simulate the behavior of photovoltaic systems under real-world conditions, taking into account:

• Losses related to module temperature, a factor often underestimated in hot regions
• The impact of the angle of incidence of solar rays on performance
• The effects of distant shading caused by surrounding terrain
• The gradual degradation of performance over time

Maria, an architect specialized in bioclimatic design in Barcelona, recently explained how PVGIS helped her convince a skeptical client: "The PVGIS simulations showed that even with a suboptimal roof orientation, the system would reach 87% of the theoretical maximum yield. This precise data turned a firm 'no' into an enthusiastic 'yes.'

A financial decision-making tool

The financial dimension is often decisive in solar projects. PVGIS24 includes economic analysis features that turn kilowatt-hours into concrete financial arguments:

• Return on investment calculation tailored to local conditions
• Projection of savings over the system's lifetime
• Comparison of different configurations to optimize profitability

For Stefan, an installer in Germany for over 20 years, this aspect is crucial: "Before, I had to juggle several software tools to present a complete report to my clients. Today, PVGIS allows me to generate a technical and financial simulation in just a few minutes that inspires confidence and facilitates decision-making."

Features that make a difference

Over the years and updates, PVGIS has been enriched with features that meet the evolving needs of the solar sector.

Simulation of grid-connected systems

The most common configuration today, where the electricity produced is injected into the grid or self-consumed, is modeled with great precision. PVGIS allows customization of every aspect of the system:

• Type and efficiency of photovoltaic modules
• Mounting configuration (roof, ground, solar trackers)
• System losses related to cabling and inverters

I recently used this feature to compare different module technologies for a community project in Italy. The simulation revealed that a slightly more expensive technology would offer better yield under the site's specific conditions, with a cumulative production difference of 7% over 20 years — a decisive piece of information for the final choice.

Modeling off-grid systems with storage

With the rise of off-grid installations and self-consumption with storage, PVGIS has developed specific tools to simulate these complex configurations:

• Optimal battery sizing based on consumption profiles
• Estimation of system autonomy
• Calculation of the energy self-sufficiency rate

For a mountain refuge project in the Pyrenees, this feature proved indispensable. "We were able to precisely size the necessary storage capacity to maintain power during periods of low winter sunlight," explains Jean, the engineer in charge of the project. "Without PVGIS, we would probably have oversized the system by 30%, significantly impacting the budget."

Comprehensive weather data

Beyond solar irradiation, PVGIS provides a set of essential weather data for optimal solar planning:

• Average, minimum, and maximum ambient temperatures
• Wind speed and direction
• Relative humidity and precipitation

This contextual information refines performance forecasts and anticipates site-specific constraints. For an agrivoltaic project in southern Spain, this data helped identify periods when solar production would be highest while coinciding with irrigation needs, thus optimizing the synergy between energy and agriculture.

PVGIS in practice: user testimonials

Numbers and features tell only part of the story. It is in daily use that PVGIS's value truly shines.

The experience of a consulting firm

Sophie runs a consulting firm specializing in renewable energies in Lyon. For her, PVGIS has become a strategic tool: "We use PVGIS from the pre-project phase to quickly assess a site's feasibility and potential. The precision of the estimates allows us to immediately rule out unviable projects and focus our resources on those with real potential."

She also highlights the value of PVGIS as a communication tool: "The generated reports are clear and professional, with graphs even the least technical clients can understand. This greatly facilitates discussions and speeds up decision-making."

The perspective of an installer

Miguel, a solar installer in Valencia for 15 years, has seen his job transformed by PVGIS: "Before, I spent hours explaining why my estimates were more reliable than the competition's. Now, I present personalized PVGIS simulations directly, and the conversation immediately shifts to equipment quality and service."

He particularly appreciates the ability to compare different configurations: "Recently, a client was hesitating between a standard installation and a solution with optimizers. In a few clicks, I was able to show him the production difference over 25 years, justifying the additional investment."

The perspective of a homeowner

Clara, owner of a house near Bordeaux, shares how accessible PVGIS is for non-professionals: "I was considering installing solar panels, but I wanted to verify for myself if the installers' promises were realistic. PVGIS allowed me to make my own estimates and ask relevant questions during commercial meetings."

She adds: "I ultimately chose an installer who also used PVGIS and whose estimates matched my research. This transparency was decisive in my decision."

PVGIS vs other tools: an informed comparison

In a landscape where solar simulation tools are multiplying, PVGIS stands out in several fundamental ways.

PVGIS and PVWatts (NREL)

PVWatts, developed by the U.S. National Renewable Energy Laboratory, is often considered PVGIS's American counterpart. Having used both tools for international projects, I can attest to their significant differences:

• PVGIS offers finer spatial resolution in Europe and Africa, while PVWatts is generally more accurate in North America
• The PVGIS24 interface is more intuitive and offers more customization options
• PVWatts provides a more simplified approach, sometimes at the expense of accuracy

A Canadian engineer I worked with on a cross-border project summarizes the situation well: "We use PVWatts for our American projects and PVGIS for our European ones. The difference lies not so much in overall quality as in the regional precision of the underlying data."

PVGIS and specialized commercial software

Solutions like AURORA or Helioscope offer advanced 3D design and modeling features, but at a significantly higher cost. PVGIS’s strength lies in its excellent cost-benefit ratio:

• Immediate accessibility without software installation
• Much faster learning curve
• Reliable and transparent data sources
• Free institutional version for basic needs

"For residential projects and small commercial installations, PVGIS offers everything we need," explains Roberto, an installer in Italy. "We reserve the more complex software for large industrial projects where detailed modeling of close shading justifies the extra investment."

The evolution of PVGIS: a look to the future

Recent improvements

The latest versions of PVGIS have introduced highly anticipated features:

• Integration of more recent and higher-resolution satellite data
• Improved performance models for emerging technologies
• Advanced tools for analyzing systems with storage
• More intuitive and responsive interface in PVGIS24

At a recent renewable energy conference in Barcelona, a JRC researcher presented the behind-the-scenes work behind these improvements: "Each PVGIS update represents thousands of hours of validation and comparison with real data from existing installations. This scientific rigor is what ensures the reliability of the estimates."

Future prospects

Several promising developments are expected in future versions:

• More advanced integration of hybrid systems (photovoltaic + wind)
• Refined modeling of bifacial technologies
• Specific tools for agrivoltaic applications
• More detailed analysis of the impact of climate change on long-term performance

An engineer involved in the development of PVGIS24 recently told me: "We are working on features that will allow the simulation of advanced self-consumption strategies, integrating electric vehicles and smart home systems. The goal is to support the transition toward more integrated and resilient energy systems."

Conclusion: PVGIS, a pillar of the energy transition

Beyond its technical features, PVGIS represents a fundamental advance in the democratization of solar energy. By making data and tools once reserved for experts accessible, it helps accelerate the deployment of renewable energies around the world.

For professionals, PVGIS has become a daily companion that makes estimates more reliable and enhances project credibility. For individuals, it is a window into the solar potential of their environment, a tool of empowerment that enables informed energy choices.

As Elena, a researcher in energy transition, eloquently summarizes: "PVGIS perfectly embodies the European spirit of innovation in the service of the common good. By transforming complex scientific data into accessible and actionable information, it concretely helps build a more sustainable and decentralized energy future."

Whether you're discovering PVGIS today or have used it for years, one thing is certain: this tool will continue to evolve and grow, reflecting the advancements of a rapidly developing solar sector and supporting the global energy transition with the precision and reliability for which it is known.

This article was written in collaboration with regular PVGIS users across Europe, North America, and South America, including researchers, solar installers, and specialized consulting firms. Their real-life experiences and perspectives enriched every section of this presentation.