Evaluating minimum battery reserve and impact on Probability of Outage Survival

[GenkiDama89]

Hello. I've dabbled with Re-Opt over the years to varying degrees but this is my first time diving in. I'm working on a PV+BESS microgrid project where the amount of PV and the BESS size is already determined, and we are trying to establish what the Probability of Outage Survival (POS) is for 3 and 6 hours durations given different minimum battery kWh reserve options. For example, if the battery is 1000kWh, we want to know what is the probability of outage survival assuming 50% of the battery is reserved for resiliency vs 25%. Grid-tied technoeconomic considerations have already been modeled in Energy Toolbase.

I ran one simulation where I tried to upload my own PV generation file. I must have not done it correctly because it appears to have run with no PV and just battery. But the result was still interesting as it recommended a ~500kWh BESS and 100% POS. When I ran it again using PvWatts for the PV production data, it now recommends a ~1500kWh BESS. It doesn't make sense to me why the minimum BESS size for 100% POS would triple when PV is available.

I would like to set the battery kWh capacity as fixed and see the impact on outage survival. I found how to set the PV size as fixed, and where to set the battery kW power output as fixed, but Is there a way to set BESS kWh capacity as fixed?

If not, any thoughts or tips would be appreciated.

[kurt-verdant]

Is there a way to set BESS kWh capacity as fixed?

If you're using the Web version of REopt, I think if you set both of the highlighted values to the same value you'll accomplish what you describe:

[GenkiDama89]

Thank you so much for the quick response earlier today. Can't believe I didn't see those fields the first time. Now I feel like I'm getting somewhere.

Question: When I look at the ERP results and the graph says the following:

Is this year 1, or is it factoring in kWh capacity degradation and giving a survival rate over the BESS expected life? I see in the User Manual it says "The REopt web tool does not currently account for battery degradation or loss of capacity over time in its dispatch and energy/power calculations". Does this mean that capacity degradation is not factored into the ERP simulation?