Issues with a battery dispatch in SAM

  • Hugh
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30 Oct 2019 16:50 #7762 by Hugh
Issues with a battery dispatch in SAM was created by Hugh
Hi there;

Working on modelling a 10kW solar system with a battery on PV (detailed, residential). I've tried to emulate the Tesla Powerwall 2 with the battery specs, and I'm trying to model controlling
it on a ToU tariff with a cheap period from 12:30-4:30am (5p/kWh vs 15p/kWh). I'm not too fussed about accuracy of financial models, but more in modelling powerflows of the system

I'm really not looking for very specific details, just a generalised view of power flows and costs etc. I've noticed that the battery seems to be underperforming significantly - with only around 30kWh to and from the battery per monthin the data output. Seems pretty low to me for a 13kWh battery!

Not entirely sure what I'm doing wrong though - I've tried changing various parameters such as dispatch modes etc. and can't seem to get it any higher than 40kWh/month from battery to load.

I'm sure it's just me being thick but any advice or direction would be appreciated. I've attached the SAM file I've been working with.

File Attachment:

File Name: 10kw_batt.sam
File Size:172 KB


Many thanks.
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  • Paul Gilman
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30 Oct 2019 23:59 #7763 by Paul Gilman
Replied by Paul Gilman on topic Issues with a battery dispatch in SAM
Hi Hugh,

Can you tell me more about how you would like to operate the battery? In the file as you attached it, the battery is set up to reduce demand charges (peak shaving), so it will only discharge once per day when it predicts the peak demand will occur. Peak demand depends on the load profile (from the Electric Load page), if the peak load is during the day, will be affected by the size of the PV system and available solar resource.

If you want the battery to charge during the times when TOU rates for energy charges are low (Period 2 on the Electricity Rates page of the file you sent), then you should use the "Manual dispatch" option on the Battery Storage page, and use the schedule matrices and parameters for each period under "Manual Dispatch Model" to allow the battery to discharge during those times. You'll have to manually replicate the weekday and weekend schedule matrices to match those on the Electricity Rates page.

Best regards,
Paul.

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