Robin Vincent

There is no real justification for limiting the number of periods to 5. It will be changed in a future PVsyst release.

We cannot help you in the definition of the periods themselves, as they are only related to your project. This information must be provided by your client or be part of your simulation assumptions.

@sarah95 When setting the unavailability factor to default, PVsyst will split the total duration onto 3 separate periods of equal length. These periods are randomly selected when you enable the unavailability factor for your different variants the 1st time. Thus, two variants using the default (random) unavailability period may end-up with very different unavailability losses. If you consider the unavailability of both systems should be the same, you can specify the same date, time and unavailability duration manually. @Auxi Madero In your variant, detailed losses ==> unavailability you can set a unavailability probability to 5%. With the rest of the settings unchanged, it will generate three random unavailability periods for a total duration of 5% of the whole year. You can find more information in the help page dedicated to the topic : https://www.pvsyst.com/help/index.html?unavailability_loss.htm

Dear sarah95, The unavailability figure defined in PVsyst represents the time fraction during which the system won't be able to produce electricity. The unavailability losses are not directly linked to the unavailability fraction, but also to when the system is not available (day, night, summer, winter, ...). Thus a same unavailability duration can give dissimilar unavailability related losses. You can find more details on our help page related to the subject : https://www.pvsyst.com/help/index.html?unavailability_loss.htm