Battery maximum State-of-Charge

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Giovani Dávi
Battery maximum State-of-Charge

Hello,

I am analyzing a detailed PV and electrochemical storage, commercial case study. Some details about the model are: battery system of 5 MWh capacity, VRLA AGM battery technology, battery bank voltage = 96 V, AC connected, battey state-of-charge (SoCmin = 40%, SoCmax = 100%). My question is: the battery state-of-charge never reaches the maximum SoC 100% over the year. I suppose could be something with respect the battery model. Somebody could me help on this?

I send attached a detailed SoC output.

Best regards,

Giovani Dávi

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Paul Gilman

Dear Giovani,

Please check the "Maximum state of charge" input on the Battery Storage input page. It is set to 95% by default for the default Lithium-ion battery. You can change it to 100% if you want to allow the battery to reach 100% state of charge.

Best regards,
Paul.

Giovani Dávi

Thank you for your reply Paul.

I am actually using SoCmaximum = 100% (SoCminimum = 40%), simulating with VLRA AGM battery technology.

Giovani

Paul Gilman

Dear Giovani,

Would you mind adding your SAM file as an attachment to your original post (edit the post to add the attachment), or emailing it to me?

Best regards,
Paul.

Giovani Dávi

Thank you Paul.

I sent you an email with the SAM file.

Best regards,
Giovani

Paul Gilman

Dear Giovani,

Thank you for sending the file, and sorry for my slow response.

There are a few things that are preventing the battery from being fully charged:

  • The system size is small compared to the load: The annual output of the system is 1.3 million kWh/yr, and the total annual load is 4.8 million kWh/yr. That means there is not a lot of excess PV energy available to charge the battery.
  • The system prioritizes meeting the load before charging the battery ("PV meets load before charging battery").
  • The grid is not allowed to charge the battery, so all charging must be done by the PV system.

Best regards,
Paul.

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