PRtemp calculation according to final report and hourly csv file

[jonipa]

Hello,

Recently I've been checking the results on PRtemp that PVSyst throws, based on the calculation they give in https://www.pvsyst.com/help/performance_ratio.htm which is indeed the one given by NREL and IEC 61724-1.

Below the results for a yearly TArrayAver= 40,79ºC. You can see the reults given by PVSyst and, in red, the ones manually calculated using the formulas mentioned above:

Date	Month	TArray	GlobInc	E_Grid	PR	PR	PR	PR temp
		°C	kWh/m²/mth	MWh/mth	ratio	temp	ratio
01/01/1990	1	18,829	98,151	4592,1	0,900	0,850	0,900	0,857
01/02/1990	2	22,082	124,36	5801,4	0,897	0,859	0,897	0,864
01/03/1990	3	26,722	176,88	8113,6	0,882	0,860	0,882	0,862
01/04/1990	4	30,465	216,64	9692,9	0,860	0,848	0,860	0,851
01/05/1990	5	37,29	270,47	11559	0,822	0,830	0,822	0,831
01/06/1990	6	42,159	292,54	12333	0,811	0,832	0,811	0,834
01/07/1990	7	47,381	321,19	13209	0,791	0,825	0,791	0,828
01/08/1990	8	47,486	288,4	12333	0,822	0,854	0,822	0,861
01/09/1990	9	40,079	212,27	9308,6	0,843	0,858	0,843	0,861
01/10/1990	10	32,068	154,07	6954,4	0,868	0,858	0,868	0,863
01/11/1990	11	23,085	103,25	4766,7	0,888	0,852	0,888	0,857
01/12/1990	12	18,789	88,653	4127,8	0,895	0,847	0,895	0,853
Yearly total		33,785	2346,9	102791	0,842	0,845	0,842	0,842

Does any one know how PVSyst calculates the PRtemp values? Seems like they are not using the formulas described in their manual.

Thank you!

[André Mermoud]

Yes PVsyst applies the definition of the PR (corrected) as it is defined in the help.

Now I don't know how you have done your calculation. This requires to be executed hour by hour (see the item "sum over hours"). 

 

[jonipa]

Thank you André,

Been checking my calculations and i am much convinced that they are correct. Yet, still don´t know why I obtain a different value for the PRtemp, must be then something odd with some value considered.

Had done it using the hourly csv exported from the advanced simulation option.

Thank you anyways