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Hi Andre This makes sense. Thank you

Hello I would like to know how exactly the maintenance costs are calculated in PVsyst. First, what is the lifetime of the battery and regulators used? Secondly, is the same maintenance specific cost for grid connected system i.e. 80Euro/kW used for stand alone as it seems there is no special value for stand alone systems and if yes which scale exponential factor is used in this case, that of grid connected (default 0.8) or stand alone (default 0.7) I tried to manually calculate the maintenance costs assuming battery and regulator lifetime to be 5 years but still get significantly lower value than that calculated by PVsyst? Thank you Amir

Hello I was wondering why the abosrptance is included in the equation used to estimate the module temperature: U · (Tcell - Tamb) = Alpha · Ginc · (1 - Effic) I mean doesn't the module efficiency already account for the TAU-Alpha? In other words shouldnt the equation be as follows: U · (Tcell - Tamb) = Alpha · Ginc · (1 - Effic/Alpha) (assuming that the cover transmittance is 1) Or the efficiency used here is actually the cell efficiency which is already divided by Alpha and is internally calculated? Thanks Regards, Amir

Hi Bruno Thank you so much for your reply. I think this is what i needed to know Regards, Amir

Hi Bruno Thanks for your reply. Do you happen to know how PVsyst estimates the glass transmittance from the module STC specifciations so it can apply the IAM? Thanks Regards, Amir

Hello How can i know and also specify the PV glass cover transmittance? Thank you Amir

Hi Andre I found it, it was right there in front of me and could not see it. Thanks Regards, Amir

Hi Andre After a revision, i realized that i still have the 1 hour shift problem. To recap, as i explained the TMY2 data are given with respect to the end of the interval. Now when i let PVsyst know that the original data are with respect to the end of the interval, it assignes all the irradiance value to "hour-1". So for example, the value of the GHI at 8:00AM on the first day of January is 66 W/m2 and PVsyst assigns this value to 7:00AM which does not quiet make sense. I mean the value at 8:00 AM should be the same and all that should vary is that the value of the last hour of the last day of the year should be assigned to the hour zero (first hour of the first day of the year) And if i ignored to inform PVsyst that the values are with respect to the end of the interval, the problem is solved but i get a warning under the data quality tab that there is a 1 hour shift in the values. Any ideas what's happening?

Hi Andre Thank you for your reply. Could you specify where exactly i can set PVsyst to use the ASCII data for the array temperature instead of calculating it using the Uvalues? In the thermal parameter window i cant see any option like that. Thanks again Regards, Amir

Hello Is it possible to import the array temperature data and use it in PVsyst instead of calculating it from the software. What i want to do is to investigate the performance of a PV/thermal modules and i have already calculated the expected operating temperature of the array using another software (PVsyst). Thanks Regards, Amir

Actually i knew what's went wrong after finding out the PVsyst manual. It would be also good if the PVsyst help can refer to the manual as the information regarding importing weather files are more detailed in the latter. Thanks

I should also note that the aforementioned issues even happened with the example Geneva CSV file.

Update: The disappearing values was mainly a file issue. Now i am able to import the weather data but i still have the following issues: 1- If i did not skip the header lines, the values are assigned to 20:00 hour instead of 7:00 as if the header files are counted as values 2- If i skipped the header files, the values are again assigned to hour-1 not considering that the original values are with respect to the end of the interval

Hi Andre I fixed the hour shift header value to 1 and i also put the values in separate cells but after converting the data in PVsysts when i open the graphs/tables to see the imported data all the values disappear. It also warns me that there is an error in the column headers (line 14, filed 8) and line indicating the units (line 15, field 8) and i cant really see anything wrong What do you think is wrong? I have attached the CSV file. Thank you Regards, Amir

Dear Andre My apologies for late reply. I have just sent you the project files to the email you have indicated Thank you so much for your help Regards, Amir

I believe the problem is because the original data is given for the end of the interval while PVsyst uses values with respect to the beginning of the interval. So i tried to change the hours manually in the original file. This solved the issue but i got a warning that "The meteo values are shifted -60 minutes by respect to the time defined by the Timezone of your site" Does anyone know why i get this warning? Thanks Amir

Hello I have been trying to import a weather data file (TMY2 from TRNSYS weather library) and i followed the format in the PVsyst help file. However, after converting the data within TRNSYS, the values are assigned to a hour-1 value for some reason (for example the GHI value for 8:00 is assigned for 7:00) Does anyone know why this is happening? I have attached the original TMY2 data CSV file (Marsa_TMY2) and the CSV file where i converted it to the PVsyst suitable format Thank you so much Regards, Amir

Hello I am designing a stand alone PV system. I ran a simulation and after checking the output excel file, i found out that while the battery SOC was in the range of 40-50% (i checked the SOC at the beginning and end of the interval as well as the average) during 1 hour interval, PVsyst shows that User energy is less than that required by the load. see below: SOC Beg SOC End SOCmean E Avail E Load E User T LOL E Miss 25/12/1990 8:00 0.4962 0.5104 0.5033 13798 47820 0 1 47820 25/12/1990 9:00 0.5104 0.5341 0.5223 23320 47820 0 1 47820 25/12/1990 10:00 0.5341 0.5666 0.5503 31938 47820 0 1 47820 25/12/1990 11:00 0.5666 0.6123 0.5894 45374 47820 0 1 47820 25/12/1990 12:00 0.6123 0.6573 0.6348 44820 47820 0 1 47820 Why the the energy available from the array and the batteries in the table above did not go to the load although it is more than what required? I realized also that while the missing power could occur for only few minutes in each hour, PVsyst multiplies the missing power by the whole hour which in this case would overestimate the results Thank you Regards, Amir

Makes sense. Thank you your reply. I dont quite get though how and why the C100/C10 is conisdered into the battery capacity pre-sizing Thanks Regards, Amir

Hi Andre First thank you so much for your reply. So in this case if my WeCycle is say 74%, what does this mean exactly? in other words what does the 74% value represent? Does it mean that in a year, the battery lost 26% if its capacity? or it means that the battery lost 26% of its lifetime so i can expect the overall lifetime to be about 4 years? Does this value give an indication of the battery lifetime? if yes then how? Thank you Regards, Amir

Hello Does anyone know how the wearing state is calculated and what does it actually represent? In other words, I want to estimate the expected battery lifetime based on the number of cycles, so can this be done? Thank you Regards, Amir

Hello I was wondering about the same thing as when i manually calculate the battery size i get higher values than those estimated by PVsyst I dont think it is correct to include the losses to the battery capacity as these losses will only affect the PV array system size. And even if we apply the self discharge, this should increase the manaully calculated value rather than decreasing it Which also makes me think why and how does PVsyst accounts for the battery energy efficiency in the pre-sizing of the battery capacity although it should only affect the PV array Thanks Amir