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Changing climate data


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I understand the update to the Metonorm database (R5) changed irradiance and therefore yield.


Can you please explain in a bit more detail the recent update to calculating irradiance in R7?


We have seen yield numbers change (sometimes dramatically) with the R5 update and again with R7. My concern is that there may be another change soon as the data source now seems to be Meteonorm 1981-1990. Is there a reason such old data is now being used?


For funded projects a change in yield mid-way though development can cause us big problems. We are keen to understand what has changed, why and what may change next.

I look forward to hearing your thoughts.




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Hi James,

you are absolutely right and we understand your worries completely. Let me try to give some more details on the updates.

In R5 we introduced MeteoNorm 7.2 (MN72) which brought new climate data worldwide and changes in the algorithm to create new climate data. For PV*SOL we preprocess a lot of climate data locations that we deliver as a database as part of the software. These pre-processed locations were generated with the new MN72 algorithm, but with the old MN71 database, which we only realized when R6 was already published.

So, for R7 we updated the preprocessed locations with the right database (from MN72). The problem now is that we overlooked a switch to choose between two climate data ranges (1981 - 1990 and 1991 - 2010).

This will be fixed in R8 which we will release very soon.

We feel really sorry for this and apologize for all inconveniences that we caused with this troublesome MeteoNorm update. This is the first climate data update we had for a long time and the first for the current team members, and apparently we did not have an adequate test coverage for this topic. Right now we setup a series of new manual and automatic tests that will cover these issues in the future.

Again, we are really sorry for that, and thank you for your feedback.

Kind regards,


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