inconsistent results of EntsoePandasClient.query_installed_generation_capacity()

[mkaut]

I am getting strange results from EntsoePandasClient.query_installed_generation_capacity(), when trying to find the development of installed production capacity from 2019:

client.query_installed_generation_capacity('DK_1', start=pd.Timestamp('20190101', tz='Europe/Brussels'), 
end=pd.Timestamp('20240101', tz='Europe/Brussels'))

returns

                           Biomass  Fossil Gas  Fossil Hard coal  Fossil Oil  Hydro Run-of-river and poundage  Other renewable  Solar  Waste  Wind Offshore  Wind Onshore
2019-01-01 00:00:00+01:00    693.0      1151.0            1915.0       208.0                              7.0            111.0  672.0  211.0         1277.0        3669.0

In other words, I get only one date.

However, changing the start date one day forward:

client.query_installed_generation_capacity(country_code, start=pd.Timestamp('20190102', tz='Europe/Brussels'), end=pd.Timestamp('20240101', tz='Europe/Brussels'))

returns

                           Biomass  Fossil Gas  Fossil Hard coal  Fossil Oil  Hydro Run-of-river and poundage  Other renewable   Solar  Waste  Wind Offshore  Wind Onshore
2019-01-01 00:00:00+01:00    693.0      1151.0            1915.0       208.0                              7.0            111.0   672.0  211.0         1277.0        3669.0
2020-01-01 00:00:00+01:00    694.0      1119.0            1915.0       210.0                              7.0            112.0   672.0  211.0         1277.0        3645.0
2021-01-01 00:00:00+01:00    695.0      1049.0            1943.0       211.0                              7.0            117.0   878.0  211.0         1277.0        3725.0
2022-01-01 00:00:00+01:00    691.0      1018.0            1943.0       196.0                              7.0            113.0  1086.0  211.0         1277.0        3888.0
2023-01-01 00:00:00+01:00    691.0       991.0            1943.0       195.0                              5.0            112.0  1702.0  211.0         1278.0        3955.0

Note that I not only get more data, but I also get the 2019-01-01 values which are now outside of the time interval.

Is this a bug, or is this expected behaviour (and if so, why)?

[fboerman]

okay thats pretty weird indeed @mkaut did you check the xml output if it also occurs there?