PVlib values different from PV GIS online tools

[FJDO]

Hello i am new to PVlib, 

i a tried to simulate a PV installation but i when i compare my results with this tools using the same Sarah weather data and parameters. I get different AC estimate from pvlib. Can someone help me understand what i am doin wrong.  

With the PVlib code i get Ac Yield of 0.422 MWh while the online tools give me 382. MWh

Thanks in advance

The PVlib online tool is here  https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html

here is my code 

lat =13.306
long = -2.372#
alti =344# m
tz='Africa/Abidjan'
location = Location(latitude =lat, longitude = long, tz =tz,altitude = alti)
#print(location)
temperature_model_parameters = pvlib.temperature.TEMPERATURE_MODEL_PARAMETERS['sapm']['open_rack_glass_glass']

weather = pvlib.iotools.get_pvgis_tmy(lat, long, map_variables=True, outputformat='json')

module = sandia_modules['Canadian_Solar_CS5P_220M___2009_']
sapm_inverters = pvlib.pvsystem.retrieve_sam('cecinverter')
inverter = sapm_inverters['ABB__MICRO_0_25_I_OUTD_US_208__208V_']

system = PVSystem(surface_tilt = 17, surface_azimuth = 180,
                 module_parameters = module,inverter_parameters = inverter,
                  albedo =0.2,
                 temperature_model_parameters = temperature_model_parameters,
                 modules_per_string = 1, strings_per_inverter=1)

print(system.pvwatts_losses())

modelchain = ModelChain(system,location)

# Run the model with the weather data
modelchain.run_model(weather_df)

# Extract the AC energy output
ac_energy = modelchain.results.ac.sum()

# Convert to MWh for annual yield
annual_yield_mwh = ac_energy / 10**6  # Convert Wh to MWh

print(f"Annual energy yield: {annual_yield_mwh:.3f} MWh")

[cwh...@sandia.gov]

The code above simulates a system made up of one module and one inverter (a microinverter). If the PV system is made up of module/microinverter pairs, you could multiply the ac_energy by the number of such pairs.

If the system is strings of modules connected to a larger inverter, you would select an appropriate inverter, modify these parameters ( modules_per_string = 1, strings_per_inverter=1), and multiply ac_energy by the number of inverters.

Cheers,

Cliff

[FJDO]

Thank you for your  fast reply, 

sorry i made i a mistake in my first text.

 With the PVlib code i get Ac Yield of 0.422 MWh while the online tools give me 0.382  MWh not 382 MWh sorry for the typo. In both system i considered an installed capacity of 220 W. 

Thank you

[Echedey Luis Álvarez]

Hi FJDO,

Would you be able to share what inputs have you used in PVGIS? At first glance, I'd say the problem is that PVGIS applies a power loss of 14% to account for general losses. But that's a blind guess, there's no way we can explain the difference without knowing the input parameters at PVGIS.

Cheers,
Echedey.

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[FJDO]

Hello,

Please find a screenshot of the parameters i used in attachment as well as the result.

[FJDO]

Hello, 

Here are the parameters i used as well as the results.

Thank you

Le samedi 14 septembre 2024 à 17:00:58 UTC-4, Echedey a écrit :

[cwh...@sandia.gov]

Not only does PVGIS reduce the energy by 14%, as Echedey points out, but I see that the pvlib simulation has a tilt of 17 degrees and the PVGIS simulation a tilt of 35 degrees. 

Cliff