Electricity rates configuration in generic battery system

Hello,
I am developing a project in a generic battery system (commercial owner) with a photovoltaic installation whose production data I know. I have done the configuration of the battery manually, by hourly periods, and charging only from the PV. As for the configuration of the electricity rate, I have some problems that I cannot find a solution to.
In Metering and Billing I want to enter the 8760 hourly invoice data. For this, I have selected Net Billing and I have placed the data in the array that the software has. In the simulation, the annual energy costs without the system coincide with my calculations, but the annual energy costs with the system (PV+BAT) do not coincide with the results. Where do you think the error could be?


The other question is in the charges for excess power. The installation has a contracted power for all hourly periods of 1600 kW (six hourly periods P1-P6). My intention is that up to 1600 kW the charges do not apply, and from this limit the charges apply for each kW that exceeds. However, in the simulation I obtain incremental demand costs that do not represent my objective. I attached a screenshot of the configuration.



Best regards,
Orlando

Hi Orlando,

I'm not sure what annual energy costs you are looking at. In general outputs with "without system" in the label are for what the electricity bill would be if there were no PV or storage system. The "with system" outputs are for the electricity bill with the PV and storage system helping to reduce the building's electric load.

For the net billing and buy all / sell all options, the hourly (or subhourly) buy rates determine the price of purchasing electricity from the grid in each time step.

The demand rate inputs determine how SAM calculates the demand charge portion of the electricity bill. The way you have defined the demand rates, the demand charge in each month should be the sum of the demand charge in each time-of-use period defined for that month. For example, the demand charge in January, February, and December will be the sum of the demand charges for Periods 1, 2, and 6. The demand charge in each time-of-use period will be the product of the peak usage in that period and the rate for that period. Because each period has two tiers and the bottom tier has a demand rate of $0/kW, there should only be a demand charge in periods where the peak or maximum usage exceeds 1600 kW over the period.

See the Electricity Rates topic in Help for more descriptions of how these inputs work: samrepo.nrelcloud.org/help/electricity_rates.htm

Best regards,
Paul.