Strong difference between Lead-acid & LiFePO4 battery systeme output

Dear all,
I am very surprising on some results. 
2 identical designs, except the battery technolgy 
Same energy : 10 kWh
Same PV system : module and inverter. 
But I don't undertand why LifePo4 discharge very quickly compare to LiFePO4. 

See the attached files.
Any comments and suggestions are welcome. 
Best regards
Ivan

Hi Ivan,

The Li-ion and Lead Acid battery chemistries have different performance characteristics, so I would expect to see a difference in the charge/discharge profiles between the two.

Could you attach a SAM file that demonstrates this behavior?

Best regards,
Paul.

Hi Paul,
Thanks a lot. Sorry for late reply.
Please find in the attached files :
- SAM model
- inverter file
- weather file
- PV module file
In SAM model, I have the two design : acid and LFP
acid is obtained from LFP by duplication. The differences are
- Battery Dispatch : acid (minimum state of charge = 40 %); LFP (minimum state of charge = 10 %)
- Battery and cell System :acid  ( Cell capacity =200 Ah); LFP  ( Cell capacity =100 Ah)
What is strange for me:
acid first year annual energy is 9448 kWh and LPF first year annual energy is 8444 kWh
Best regards
Ivan

Hi Ivan,

The difference in annual output between the two cases has something to do with the interconnection limit. You can see that on the Losses page, and also by showing the "Annual energy loss from interconnection limit (year 1) (kWh) value. If you disable the interconnection limit, the two cases have the same annual energy value.

I'm not sure exactly why that is different between the two cases, but suspect it has to do with the way SAM is dispatching the lead acid and Li-ion LPF battery. The two battery types have different charge and discharge characteristics.

If you look at the battery state of charge (SOC) on the Time Series tab, you can see for the lead acid battery that between May and June, the SOC range suddenly drops from up to 90% to less 20%. I will investigate further and let you know what I find.

Best regards,
Paul.

Hi Paul,
Thanks a lot.
I confirm that without the grid interconnection limits I get more energy and
almost the same value for the 2 type of battery!
However, bylooking closely to the time series graphs, there are clearly a difference between
the 2 type of battery. Please let me know if you find some things. Also, any peace
of advices are welcome.
Bestregards
Ivan

Hi Ivan,

We are still investigating, but did notice that the lead acid battery temperature increases suddenly between May and June, which causes the cell voltage to drop and reduces the battery's ability to fully recharge. That is probably due to the heavy cycling of the lead acid battery. The 15 kWh / 15 kW battery has one hour of storage capacity, and the manual dispatch is set to allow the battery to discharge 100% of its available capacity in a single hour, which is causing the battery to heat up, which in turn reduces its ability to hold a charge.

You might try reducing the kW rating of the battery and/or reducing the discharge percentage in the dispatch to a lower number to reduce the battery temperature.

Best regards,
Paul.