How to mode BIPV connected to Ecoflow

[Zahra]

Hello, I am conducting an experimental study on the degradation of a Building-Integrated Photovoltaic (BIPV) system, which uses a single semitransparent Photovoltaic (STPV) module on a facade at a 90-degree tilt connected to an EcoFlow portable power station that functions as both the inverter and battery. I am seeking guidance on the most accurate way to model this setup in PVsyst, as I have two primary questions: First, the setup is not connected to the grid and the EcoFlow's battery capacity is a fixed component that was not sized based on an energy demand profile, is it more appropriate to model this system as grid-connected rather than standalone? Second, given that the EcoFlow unit combines the inverter and battery, what is the recommended approach for modeling it? If I need to represent it as separate components, I would appreciate guidance on the key technical parameters that are essential for an accurate simulation.

[André Mermoud]

The Stand alone systems simulation in PVsyst is based on a balance between the PV production, the user's consumption and the intermediated battery for ensuring a match at each instant between these two energy systems. Therefore if you don't define the user's needs, the simulation cannot work, and I really don't see what you want to obtain as a result.

Now if you consider this as a grid-connected system with storage, this should be a self-consumption system, and the problemremains the same: without self-consumption definition this doesnt make sense.  

You can indeed consider a grid-connected system, without storage, for the evaluation of the possible PV yield. This will not involve the battery. The battery behaviour is obviously dependent on when you will consume this energy, therefore on the user's needs definition. 

 

 

 

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[Zahra]

Hello André,

Thank you for your response. As I mentioned, I used an EcoFlow unit in my setup, which includes both an inverter and a battery. I am planning to add a heater as the load.

For clarification, do you think it is appropriate to model this system as grid-connected, even though it is not physically connected to the grid? Also, since the EcoFlow integrates the inverter and battery, what would be the recommended approach for modeling it? If it is OK to represent them as separate components, I would appreciate your guidance on the key technical parameters needed for an accurate simulation.

Best regards,
Zahra

[André Mermoud]

The EcoFlow is a grid-tied inverter, which can only be used (in PVsyst) in a grid-connected system. 

Now if you want to use it in a stand-alone system - which is probably more suited for your very special use -  you should define it as a  "Controller for Stand-alone" in the database. 

But the problem of the user's needs definition remains the same: you have to define it, whatever the way you are using the produced energy. The battery needs to "know" when it has to be charged or discharged. 

 

 

 

 

[Zahra]

On 8/27/2025 at 4:30 AM, André Mermoud said:

you have to define it, whatever the way you are using the produced energy. The battery needs to "know" when it has to be charged or discharged

Hello André,

Thanks for your response. I have a question regarding user consumption. The EcoFlow has an option to set thresholds for the battery to start charging and discharging (e.g., discharge when the battery reaches 80% of its capacity and recharge at 20%). Is it possible to model this behavior in PVsyst? I understand that consumption can be modeled on an hourly basis, but is there a way to represent it based on these charging thresholds instead?

Also, please correct me if I am wrong, but I thought that if I don’t want to calculate battery sizing, it might be more appropriate to model my setup as grid-connected rather than standalone (since I am working with a fixed EcoFlow unit).

Best regards,
Zahra