{"id":144746,"date":"2026-08-17T17:12:22","date_gmt":"2026-08-17T15:12:22","guid":{"rendered":"https:\/\/www.velasolaris.com\/?p=144746"},"modified":"2026-08-17T17:13:52","modified_gmt":"2026-08-17T15:13:52","slug":"bringing-polysun-up-to-date","status":"publish","type":"post","link":"https:\/\/www.velasolaris.com\/en\/bringing-polysun-up-to-date\/","title":{"rendered":"Bringing Polysun up to date: more precise collector simulation, new licence management and the road to ISO 9806:2025"},"content":{"rendered":"\n

Versions 2025.5 and 2026.1 modernise the calculation basis for solar thermal and PVT systems. The simulation now follows ISO 9806:2017 and the collector parameters are taken directly from the Solar Keymark database. This eliminates the need for any conversion steps. Anyone with existing projects set up under the old standard should re-simulate them, since the differences can be substantial, particularly for unglazed and PVT collectors. The switch pays off twice over: from version 2026.3, Polysun will adopt a user-based licensing system, enabling you to implement the standard update and licence transition simultaneously.<\/strong><\/p>\n\n\n\n

Winterthur, August 2026 <\/strong>
The quality of the planning for solar thermal and PVT systems fundamentally depends on the quality of the underlying collector data. Versions 2025.5 and 2026.1 of Vela Solaris have modernised the Polysun calculation basis to the ISO 9806:2017 standard. From version 2026.1 onwards, Polysun will also access the Solar Keymark database directly. Since then, collector parameters have come straight from certified manufacturer data, with no conversion steps required.<\/p>\n\n\n\n

In practical terms, this means that anyone still working with an older Polysun version or projects set up under previous standards should recalculate them. This is particularly important for unglazed and PVT collectors, as the differences between the old and new standards can be significant.<\/p>\n\n\n\n

Why updating now pays off twice<\/h2>\n\n\n\n

From version 2026.3 onwards, Polysun will switch to a user-based licensing system. Anyone updating the software now can handle both the standard update and the licence transition in one go.<\/p>\n\n\n\n

What the change in standard means technically<\/h2>\n\n\n\n

Here’s what the change in standard means technically: the key difference between the new ISO 9806:2017 standard and its predecessor, ISO 9806:2013, lies in how wind speed is treated. Under the ISO 9806:2017 test procedure, wind speed is reduced by 3 m\/s. This has a minimal impact on glazed collectors, but for unglazed collectors, wind significantly influences yield. If collectors with test data based on ISO 9806:2013 are entered into Polysun, this can lead to an underestimation of solar yield. In combination with a heat pump, this can result in COP deviations of between +0.3 and +0.6.<\/p>\n\n\n\n

Vela Solaris therefore recommends using ISO 9806:2017-certified collectors and the latest version of Polysun for all projects.<\/strong><\/p>\n\n\n\n

Outlook: Polysun will integrate ISO 9806:2025<\/h2>\n\n\n\n

Work on the standards is ongoing. For the first time, the new ISO 9806:2025 establishes a clear international framework that differentiates PVT collectors by performance class. Vela Solaris will update Polysun as soon as manufacturers provide the necessary catalogue data. Those who are up to date at that point will benefit immediately.<\/p>\n\n\n\n

What users should do now<\/h2>\n\n\n\n

Users should re-simulate existing solar thermal or PVT projects created under older standards or in older Polysun versions using the current version. The effort involved is minimal, but the payoff is planning certainty on a standards-compliant basis.<\/p>\n\n\n\n