Solar power plant designers across Ukraine rely on one tool above all others — PVGIS. This free solar resource calculator is maintained by the Joint Research Centre of the European Commission (JRC) in Ispra, Italy. According to the European Commission — Joint Research Centre, PVGIS delivers monthly irradiation values for any geographic point and immediately calculates the optimal solar panel tilt angle — a parameter that has a significant impact on annual energy yield.
Key takeaways:
- PVGIS 5 draws on a satellite archive covering 2005–2020, with a stated accuracy of ±5% for daily values.
- For Kyiv (50.45° N) the optimal tilt is 35–42° facing south; for Kharkiv — 38–42°; for Odesa (46° N) — 32–36°.
- In Kyiv, monthly irradiation on an optimally tilted surface reaches ~160 kWh/m² in June and drops to ~30 kWh/m² in December.
- Moving from a horizontal to an optimally tilted installation adds up to 25–30% to annual energy output.
What “Monthly Radiation” actually calculates
The tool processes multi-year satellite data and returns average monthly values for global horizontal irradiance, irradiation on an optimally tilted plane, and direct normal irradiance (DNI). Notably, PVGIS reports the optimal tilt angle directly in its output — even when the user has not requested it explicitly. The PVGIS 5 satellite archive spans 2005–2020, and the stated accuracy for daily values is within ±5%.
Optimal tilt angles for Ukrainian cities
Geographic latitude determines how steep a south-facing module should be. According to PVGIS 5 calculations, the optimum for Kyiv (50.45° N) falls in the 35–42° range. Kharkiv, at a similar latitude, sits at 38–42°. Further south, Odesa (46° N) has a lower optimum of 32–36°. These figures represent a fixed tilt for maximum annual yield; seasonal optimization — separate values for summer or winter operation — will produce different results.
Why tilt matters more than it seems
For Kyiv, PVGIS reveals a sharp seasonal contrast: roughly 160 kWh/m² on an optimally tilted surface in June versus ~30 kWh/m² in December. When panels are laid flat, winter losses are even greater — the sun sits low on the horizon and rays strike the module face at a steep angle. This is precisely why switching from horizontal to the optimal tilt adds up to 25–30% to annual output. Proper array planning also requires attention to the spacing between rows of solar modules; without it, mutual shading can cancel out the gains from correct tilt.
How to apply this in practice
PVGIS is the de facto standard for solar power plant design in both Ukraine and the EU. For a residential system, the “Monthly Radiation” result gives a direct answer to the question of what angle to use for roof or ground-mounted racking. For larger sites, a shading analysis is added to the calculation, and options for increasing PV array output are evaluated with the actual tilt angle and row spacing already factored in.
For anyone planning a solar panel installation, the conclusion is straightforward: skip the generic tables from online forums and open PVGIS instead. Enter your site coordinates and get a figure specific to your location. PVGIS calculates the precise optimal tilt angle individually for every point, and the 25–30% gain in annual yield that comes from moving away from a flat layout is a real advantage worth building into the project from the very start.
Sources: European Commission — Joint Research Centre (PVGIS)
Illustration generated with AI
Prepared by the Alternative Energy editorial team with the help of AI based on the sources listed; facts and figures were checked against them during automated editorial review. How we prepare articles
