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Change the start date of simulation


Rasmus Luthander
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Hello everyone,

I'm simulating an off grid system (PV panels + batteries) where availability is the top priority. Since the irradiance is quite scarce in the winter (the system is going to be placed near Stockholm, Sweden), I would like to simulate for July to June instead of January to December as seems to be default.

The problem is that the state of charge/SOC of the batteries on January 1st at 00:00 differs from the SOC on December 31st at 23:59, which results in a higher availability in January than it would be in real applications. So my question is if it is possible to change the start date/simulation period, or if there are any other solutions to this?  

A solution with a generator is unfortunately not possible for this application. 

Thanks in advance,

Rasmus

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Hi Rasmus,

sorry for the late reply. A simulation with another start or end date is not possible I am afraid. But concerning your concrete request about the SOC in offgrid systems: When the simulation starts, the batteries are set with an initial SOC value. In the case of offgrid plants, this is pre-calculated as an expected average SOC from the backup generator SOC thresholds. Even if the backup-generator is not used in the system, ie if you have chosen a system without backup generator, these thresholds are used. This was done for historical reason (in terms of software development), and we plan to change it in the future, but right now it would help you to manipulate the starting SOC.

Just select the system type with diesel generator, set the SOC control thresholds to 80 and 90 respectively, and then change the project type back again. If you run the simulation now, the starting SOC will be between 80 and 90 %. No guarantee that this will work in the future :) but then we will have some other sort of editable starting value.

image.png

For on grid battery systems the starting SOC value is fixed at 80%.

For electric vehicles the starting SOC value is fixed at 100%.

Hope that helps, kind regards,

Martin

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Hi Martin,

thanks for the answer. I have, however, the opposite problem - if the SOC is 20% in the end of December, it should start at 20% in January to simulate a continuous operation, just to examine number of hours when the load has to be disconnected.

But I found a workaround; to set the "Preservation Mode" to 40%, and thereafter recalculate the battery capacity to fit to a minimum SOC of 20%. That seems to work :)    

Best regards,
Rasmus

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