Unnecessary Grid Usage Despite Available Solar – How to Prioritize Self-Consumption?

[OSS_QV]

PVsyst 8.0: I’m modeling a grid-tied, zero-export PV system (no batteries) and encountering an issue where the grid supplies power even when solar generation is available.For example, in January, Solar should cover all possible load (73.7 + 82.2 ≈ 156 MWh), leaving only 25 MWh to the grid. Instead, the grid supplies 107.5 MWh, and 82.2 MWh of solar is wasted.

I have set grid limitation to 0 kW (no export) and applied at the inverter level.

 

[Bruno Wittmer]

The monthly values do not tell whether PV generation and load are aligned all the time. If you don't have any storage in the system, the load may not be covered in different situations, like outside daylight hours, early in the morning or evening if the load is high, or during cloudy periods in the middle of the day. Therefore, it is quite normal, that you cannot self-consume all the monthly or yearly PV generation, even if it is less than the integrated consumption.

[Greg]

Hi,

I'm currently designing a 35 MWp grid-connected solar farm with a 100 MWh Battery Energy Storage System (BESS). The system is configured so that the BESS charges exclusively from the PV array — not from the grid.

However, after exporting the hourly data from PVsyst, I noticed that values appear for EFrGrid (energy from the grid). When reviewing the simulation settings, I couldn’t find an option to disable grid import explicitly.

Has anyone encountered this issue before? Is there a specific setting or workaround to ensure the simulation fully restricts energy import from the grid?

Any guidance would be appreciated. Thank you!

[Bruno Wittmer]

Hi Greg,

In PVsyst the grid-tied systems with storage will never charge the batteries from the grid. The non-zero values for EFrGrid are situations where PV generation and battery discharge together are not enough to cover the load, and therefore power needs to be imported from the grid. This typically happens at the end of the night and early in the morning when batteries may be discharged and PV generation is still low. It can also happen after a series of cloudy days that did not allow to fully charge the batteries.