The photovoltaic potential of Italian public administration roofs

How much photovoltaic power could be installed on the roofs of schools, hospitals, town halls and other buildings belonging to the Italian Public Administration? Heiwit has built a bottom-up model to provide an initial quantitative answer and, alongside the results, is also publishing the limitations that emerged from the audit.

The study in one minute

The model starts from a frame of 41,254 OpenStreetMap elements classified as schools, hospitals, town halls and other facilities with functions attributable to the public administration. It is not correct to automatically call it a «census of public buildings»: a functional tag does not prove public ownership and an OSM element can be a point of interest, a building or an entire complex.

Based on a stated stratified sample of 10,000 units, of which 9,318 had valid data, the model combines geospatial data, the Google Solar API, PVGIS and a spatial comparison with GSE Atlaimpianti. The stated theoretical result is 5.68 GWp and 7.53 TWh/year. Compared with the PNIEC, 5.68 GW is equivalent to 7.17% of the overall photovoltaic target of 79.2 GW, or 13.46% of the arithmetic gap compared with the 37.002 GW in operation by the end of 2024. The two indicators have different denominators and should not be confused.

Why the content is relevant

• Pre-existing surfaces: The roof does not require new land take, whilst structural, landscape, fire safety and connection checks remain necessary.
• Potentially daytime loads: hospitals, offices and some school activities can consume while photovoltaic systems are generating, but self-consumption must be calculated using real hourly profiles.
• National scale: Public assets make it possible to build standard procedures, aggregated portfolios and replicable investment models.
• Demonstration effect: A solar-panelled school or hospital makes the energy transition visible to the public.

What we have rectified following the audit

The review identified an inconsistency between the 96.5% attributed to Google’s coverage, the 3.5% for the PVGIS fallback, and the 174 cases reported. One hundred and seventy-four records represent 1.74% out of 10,000 or 1.87% out of 9,318, not 3.5%. Furthermore, 682 records remain to be classified between the initial sample and the valid sample. These points are published until the logs allow them to be reconciled.

The comparison with Italy’s projected electricity demand for 2024 – 312.285 TWh according to Terna – has also been updated: 7.53 TWh would correspond to 2.41%. The ISPRA factor used for an average estimate of emissions avoided has been updated to 192.6 gCO₂/kWh; this results in a theoretical maximum credit for the first year of approximately 1.45 MtCO₂, which is neither a certain nor a marginal reduction.

Documents to download

The series of in-depth articles

Project responsibilities

OpenStreetMap: © OpenStreetMap contributors. Data available under the Open Database Licence (ODbL) 1.0; extraction date: April 2026.

Google Solar API: Source: includes solar data from Google. Aggregated analysis by Heiwit S.p.A.; Google is neither the author nor the validator of the study.

PVGIS: PVGIS © European Union / European Commission, Joint Research Centre (JRC), version 5.2. Data processed by Heiwit S.p.A.; the results do not necessarily reflect the position of the European Commission.

GSE Atlaimpianti: Source: Gestore dei Servizi Energetici – GSE S.p.A.; Heiwit S.p.A. processing. Atlaimpianti does not coincide with the complete census of Italian plants.

Cover images: graphic design by Heiwit S.p.A. based on original project materials. They do not depict a specific public building or an actual plant layout.