Hossam Posted February 27, 2023 Share Posted February 27, 2023 The meteonorm 8.1 database has hourly values of ambient temperature. Does PVsyst calculate the Cell temperature using the ambient temperature value at the specific time during the simulation or it uses the monthly average for all days? I mean does it calculate the cell temperature only during daylight or it merges all heat transfer throughout the year, day and night. Link to comment Share on other sites More sharing options...
Michele Oliosi Posted March 24, 2023 Share Posted March 24, 2023 Dear Hossam, the cell temperature is calculated with the ambient temperature at each specific hour. Link to comment Share on other sites More sharing options...
Hossam Posted March 28, 2023 Author Share Posted March 28, 2023 Does it include the ambient temperatures at night in the simulation of thermal losses? Link to comment Share on other sites More sharing options...
Michele Oliosi Posted March 28, 2023 Share Posted March 28, 2023 By thermal losses we only account the losses due to the loss of efficiency when the module heats up during the day. Unless you are concerned with infinitesimal variations of temperature, since the thermal inertia of modules is about 10 minutes, you don't need to merge the heat transfer throughout the year, day and night to simulate in hourly steps. Considering the heat transfer within the hour is enough. Link to comment Share on other sites More sharing options...
Hossam Posted March 30, 2023 Author Share Posted March 30, 2023 This means the losses are only calculated using the hourly temperature values only in the presence of irradiance or throught the day (24 hours)? Link to comment Share on other sites More sharing options...
Michele Oliosi Posted April 4, 2023 Share Posted April 4, 2023 Only in the presence of irradiance. By definition there will be no thermal losses at night. Link to comment Share on other sites More sharing options...
Hossam Posted April 4, 2023 Author Share Posted April 4, 2023 This means PVsyst recognizes the time where there is no irradiance and then does not calculate the thermal losses unless the irradiance presence is provided in the hourly values table. Is this right? Secondly, How can I export the meteonorm 8.1 data used in my simulation as I need to edit only the ambient temperature. Thank you Link to comment Share on other sites More sharing options...
Hossam Posted April 5, 2023 Author Share Posted April 5, 2023 On 4/4/2023 at 11:59 AM, Hossam said: This means PVsyst recognizes the time where there is no irradiance and then does not calculate the thermal losses unless the irradiance presence is provided in the hourly values table. Is this right? Secondly, How can I export the meteonorm 8.1 data used in my simulation as I need to edit only the ambient temperature. Thank you @Michele Oliosi Link to comment Share on other sites More sharing options...
dtarin Posted April 5, 2023 Share Posted April 5, 2023 Export the 8760 and create a custom weather file then reimport. Link to comment Share on other sites More sharing options...
Hossam Posted April 5, 2023 Author Share Posted April 5, 2023 Can you explain what is the 8760 ? Please attach media. Thank you so much. Link to comment Share on other sites More sharing options...
Michele Oliosi Posted April 6, 2023 Share Posted April 6, 2023 it's the colloquial name for a hourly output file (8760 hours in a year) see https://www.pvsyst.com/help/output_file.htm Link to comment Share on other sites More sharing options...
Hossam Posted April 7, 2023 Author Share Posted April 7, 2023 On 4/4/2023 at 11:59 AM, Hossam said: This means PVsyst recognizes the time where there is no irradiance and then does not calculate the thermal losses unless the irradiance presence is provided in the hourly values table. Is this right? Secondly, How can I export the meteonorm 8.1 data used in my simulation as I need to edit only the ambient temperature. Thank you @Michele Oliosi Please tell me the answer of the first question. Thanks in avance. Link to comment Share on other sites More sharing options...
Hossam Posted April 7, 2023 Author Share Posted April 7, 2023 On 4/6/2023 at 11:22 AM, Michele Oliosi said: it's the colloquial name for a hourly output file (8760 hours in a year) see https://www.pvsyst.com/help/output_file.htm If I export the excel file using only the meteo data then If I import it again, it will be recognized as a new meteo file in PVsyst? Thanks in advance Link to comment Share on other sites More sharing options...
Michele Oliosi Posted April 17, 2023 Share Posted April 17, 2023 On 4/4/2023 at 11:59 AM, Hossam said: This means PVsyst recognizes the time where there is no irradiance and then does not calculate the thermal losses unless the irradiance presence is provided in the hourly values table. Is this right? Indeed that is correct. Link to comment Share on other sites More sharing options...
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