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Beopt v3 bess modeling

asked 2023-07-03 12:05:01 -0500

Rohit Jogineedi's avatar

updated 2023-07-03 12:11:56 -0500


I've been trying to model a PV (4.5 kWh) + BESS (10 kWh) system in the recent beta3.0 version of BEOpt, which was supposed to have improved modeling features for hybrid/integrated systems. However, after doing some post-processing the data obtained is not showing a reasonable hybrid/integrated PV+BESS model. I've extracted the hourly outputs into an excel sheet and tried to calculate the cumulative battery capacity values to understand its working characteristics. The cumulative battery capacity values look fine up to a certain extent, however as time passes, the battery starts accumulating values greater than 10 kWh (beyond its selected capacity) and end up reaching 147.72 kWh to the end of the year.

Here is the link to the Excel sheet:

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@Rohit Jogineedi you can upload your Excel file to a file sharing service like Dropbox, Google Drive, etc. and then share a link in this post for others to access.

Aaron Boranian's avatar Aaron Boranian  ( 2023-07-03 12:08:32 -0500 )edit

@Rohit Jogineedi thanks for sharing the Google Drive link. It looks like the sharing settings is not open to anyone with the link, it asked me to request access. Just in case you want to make it easier for others to access the file.

Aaron Boranian's avatar Aaron Boranian  ( 2023-07-03 15:46:52 -0500 )edit

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answered 2023-07-05 10:18:58 -0500

JMaguire's avatar

@Rohit Jogineedi: I can explain what's happening here. There's currently a bug in how the battery model was implemented in EnergyPlus related to how to account for the round trip efficiency of the battery (see To work around this and still track losses, we added an EMS program that takes the losses into account as additional energy consumption, but it only applies during charging, not discharging. We have a note about this in the documentation (https://openstudio-hpxml.readthedocs....): "The round trip efficiency affects charging; the reported charging rate will be larger than the schedule value by an amount equal to the losses due to the round trip efficiency." If you apply the round trip efficiency to charging I'm pretty sure this will net out to 0.

Let me know if you have any additional questions about the battery model, I did the bulk of the implementation on this one. When the EnergyPlus issue is fixed we'll switch to a more direct model for accounting for battery losses rather than this EMS workaround.

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Thanks for the help. I shall go through the provided documentation and will get back to you if I have any questions.

Rohit Jogineedi's avatar Rohit Jogineedi  ( 2023-07-06 16:42:12 -0500 )edit

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Asked: 2023-07-03 12:05:01 -0500

Seen: 129 times

Last updated: Jul 06 '23