Battery Degradation Integration into Charge / Discharge

  • koryli90
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10 Oct 2022 09:37 #11543 by koryli90
I was able to pull the battery degradation profile from SAM; however, I wanted to see if there was a way to tie this to the charge/discharge profile and ultimately into our revenue / expense line items in the cash flow output. Looking through the cash flow profile, the charge/discharge amounts in year 1 vs year 20 are very similar and not sure if this is a result of the degradation not being correctly inputted. I've attached the sam model file to this message for reference 

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  • pgilman
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10 Oct 2022 14:32 #11547 by pgilman
Hi Kory,

SAM should account for the effect of battery degradation on the project cash flow: As the battery capacity degrades over time, the battery can store less energy, and if the battery degrades to less than the battery bank replacement threshold and battery replacements are enabled on the Battery Life page, you should see a battery replacement cost in the cash flow for the year(s) they occur.

If you are not seeing those results, then it is possible that the battery is not being significantly degraded, which could happen if it is not being cycled too often, or not being deeply discharged too often, and being maintained at a reasonable temperature.

Best regards,
Paul.

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  • koryli90
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11 Oct 2022 08:14 #11556 by koryli90
Thanks Paul - is there any way to show the effect by line item of both calendar and cycle degradation on the charge/discharge profile in the output results? 

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  • koryli90
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11 Oct 2022 08:48 #11557 by koryli90
As a quick follow up, we disabled battery cell replacement in our simulation - would this mean that once a cell is thoroughly degraded, it would not be replaced?  Given this profile, would that mean we can run the battery system out for significantly longer periods? I would imagine that there would be some calendar degradation effect as well 

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  • koryli90
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11 Oct 2022 09:18 #11558 by koryli90
Looking further, we were able to find the capacity %, but it looks like there isn't any degradation being factored in here. The relative capacity curve from both a cycle and calendar seem constant over time, does this mean that there is no degradation over the life of the battery? 

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  • pgilman
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11 Oct 2022 11:58 #11561 by pgilman
Hi Kory,

The annual profile graph on the Profiles tab of the Results page is not very useful for showing change over the life of the project. The profile shows the average annual change over a day. It is useful for looking at the generation profile of the system.

To see the effect of battery degradation over the project life, plot the battery capacity variables on the Time Series tab, and zoom out all the way to see the entire lifetime. This example shows the effect of battery replacement on its capacity, and you can see that battery cycling dominates calendar degradation:



Best regards,
Paul.

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