Sang Han

@dtarin @André Mermoud, Thanks for your help!

When I unchecked the "Night Disconnection" in MV and HV transformer loss input section, the more loss occur at nigh. MV and HV losses are increased when I see the 8760. so I think night losses connected with the grid at night is related to TX losses and fans, HVAC, and others.

My result by PVsyst regarding the nighttime loss is 0.04% with disconnection for MV and HV transformers. But once I have these (MV&HV night loss) included, 0.33% of nighttime aux loss occurs. When I contact an interconnection engineer, he said I need to include transformer night losses due to the grid stability based on interconnection agreement. 0.33% will be used for my calculation. Any comments on this?

In PVsyst, how can I calculate aux-load loss that the grid provide to a PV plant which we should pay for the utility? Aux-load loss is generally 0.3% for the 100-200MW utility scale solar project. But that loss can be cutoff by PV plant itself during a day. What I want to know is the aux-load usage that utilities provide when PV plant is not operating such as nighttime loss or no-load loss for Inverters or transformers? How can I calculate that?

Thanks for the reply, I will try that.

In PVsyst, is there a set up to charge BESS first and then discharge the energy into the grid at night such as 7 to 11PM? My utility solar project is 600MWdc and 450MWac at POI. We considered the 264MW x 4hours system using Sungrow ST5015UX-4H-US. When I used Peak Shaving mode, it only charged the extra energy over the POI limit, so once I see the result, it shows only 1.5% of energy was stored during a year. Our goal of the design is charging the energy into BESS during a day and then discharging it after 7PM for 4 hours. Can you give me advice? Also please let me know if PVsyst can support DC or AC coupling separately. Thank you.