Thank you for your support, let me tell you that system is grid-connected and what i am evaluating is PR because i have to warranty system and we have zero export system that not allow energy injected to grid (in my country, if the system is consumption type. they not allow enrgy inject to grid). In my understanding, in case of shut down system to maintenance, it directly impact to PR because of Zero export system.so PR will go down. So i want to know that if i known the exact schedule for matenance or their vacation that is the system cannot product energy what PR value i have to warranty due to such condition.Therefore, i think it relate to this function,"unavailability", right? . and if the caculation that i have shown you is not work how can i solve this solution. Could you advise please. Thank you very much