I would like to ask a question about the losses about regulation on account of MPP Voltage Range.
Actually I work on effect of MPP range on total energy yield and now I use trial version of PVSOL to check whether the software gives expected results or not.
Minutely simulations are supposed to seize the instantaneous voltage drops on PV arrays due to momentary low irradiance values that exist quite frequently in cloudy weathers. So inverters whose MPP range extends towards lower voltages can keep operating with relatively high efficiencies compared to the inverters with narrow MPPT range in low irradiations.
In order to test this situation, I made a simulation. Simulation parameters are given as follows:
- Location: Berlin/Germany
- "Simulate the irradiance with synthesized minute values" option is checked.
- PV Modules: ASUN250-M (A-sun by Aton Energy), 400 Modules (20 Strings, each string has 20 series modules), 100kW PV Nominal power
- Inclination is 30 degree, azimuth is 0 degree.
- Installation type is roof parallel.
- Inverter is PVS800-57-0100kW-A (100kW Central Inverter of ABB), its MPP voltage range is defined as 450V-825V. - Other options are set as default.
After this simulation, a virtual inverter is defined. Parameters of this virtual inverter is exactly same with PVS800-57-0100kW-A but its MPP range is specified set as 100V-825V. And same simulation is repeated with this new virtual inverter.
Comparison of these simulation results are given as a PNG file as attached [Comparison of MPP Range.png]. Total difference between the grid feed-in values is only 38.1kWh that seems too low to me. There is no loss due to MPP voltage range in second simulation as expected. What surprises me is that losses due to the regulation on account of MPP voltage range is only 26,02kWh which corresponds to only 0,02% of all losses in first simulation. Isn't it too low?
After this result I repeated the first simulation with hourly taken irradiance data and losses due to the regulation on account of MPP voltage range is found as 21,04kWh that is just 5kWh less than the result of simulation where we used minutely taken irradiance data as input. I believe there is something wrong (maybe I did not do something correctly) as irradiance data in minute steps is expected to seize the instantaneous voltage drops on PV modules due to momentary low irradiances. However simulation results show that the difference between minutely taken irradiance data and hourly taken irradiance data is just 5kWh on losses due to the MPP range at the end of a year which is just neglicible for a 100kW nominal DC power system. So am I doing something wrong? Maybe someone can give me a reasonable explanation here Thanks Oğuzhan