Simulating a 75MWp/50MWac PV + 20MW/40MWh BESS

[Ken]

Hi,

I am trying to simulate a 75MWp/50MWac PV + 20MW/40MWh BESS system with grid limitation at 50MW in which the excess is used to charge the BESS. However, the requirement is to ensure that the BESS is able to fully charge and discharge 20MW for 2hours daily. Theoretically this should amount to an average of 1.2GWh per month or 14.4GWh per year. However, based on the results obtained, the EBatDis is only at 4.3GWh per annum. 

 

 

Storage strategy is set to Peak Shaving with the following parameters

 

 

Please advise if there is any settings changes to be made to achieve desired outcome.

[Robin Vincent]

With the Peak shaving strategy, you will indeed put any excess production into the battery with respect to the charger max power and battery state of charge. 

In these conditions, you can charge your battery up to 20MW, but only if the total AC power is 50+20MW. 

Your system will always output less than 70MW (max clear sky production being estimated to 68.23MW), but will also charge for more than 2 hours a day, so your daily charging energy will be somewhere between 0 and 40MWh/day.

The actual energy will depend on the weather and battery state of charge at the beginning of the day, so you cannot predict the charging/discharging energy based on the max charging power.

[Ken]

Hi Robin,

 

Thanks for the confirmation. Should there be a customer requirement for the batteries to be of capacity 20MW and to discharge for 2 hours on a daily basis, is it even possible to simulate this in PVsyst? 

[Robin Vincent]

With Peak shaving, the strategy is relatively simple: charge the battery with excess energy and discharge the battery into the grid up to the grid limitation value.

You could set up your system to start discharge during the night (i.e with PV zero production). In this case, you will discharge at the max inverter power (20MW) until the battery is empty.

To ensure your battery is fully charged each day, you can use the power shifting strategy instead

Using the "Fixed charging power before exporting" will prioritize battery charging before grid injection.

This won't guarantee a full 40MWh/day of charging if the PV production is lower than that, but you should be closer to your target.

This will probably lower your overall PV production though, since the battery will be more likely to be fully charged when your PV production reaches the grid limitation.