PPA for BESS + PV

Hi,

I'm doing a PPA analysis for a BESS + PV project.

I'm assuming 0% debt, as the client will be paying the financer based on a PPA rate.
I'm not assuming any revenues that goes to the client from the energy generated, as that will go to the financer.

There are important global adjustment savings achieved by the implementation of the BESS.
Where do I include this? They should be in $/kW.
I'm assuming the capacity based payments in $/kW will be what the client will be paying the financer for the BESS portion exclusively.
The PV will be paid in $/kWh.

If you can assist me with this, I'll appreciate it.

I look forward to hearing from you.

Best Regards,

Rafael Corral

Hi Rafael,

The capacity payments on the Revenue page are in $/MW of system nameplate capacity as defined on the System Design page. If the project only receives capacity payments for the battery maximum discharge capacity, you adjust the capacity payment accordingly.

For example, if you had the following assumptions:

Nameplate capacity = 100 kW
Battery discharge capacity = 30 kW
Capacity payment = $5/MW of battery capacity

You could set the capacity payment to:

Capacity Payment = ( 30 kW / 100 kW ) * $5/MW = $1.5/MW

Or, you could set the capacity payment to $5/MW and set the capacity credit to 30%.

In either case, you should verify the capacity payment revenue on the Cash Flow tab in the Revenue section of the cash flow.

Best regards,
Paul.

Hi Paul,

Thank you very much for your quick response.
But then my capacity payment in $/MW will be the savings achieved by implementing the BESS? That's how I understand it.
However, in the capacity payments, I'm having both the BESS and the PV system.
We're not receiving anything for the PV. How can I make that adjustment?
We're installing a 2 MW BESS and a 1.56 MW PV.

Also, my client will need to pay the financier for both $/ kWh (which I'm assuming is the PPA rate) and in $/kW. Where will that information be included?

Finally, should I have my debt as 0%?

Thanks,

Rafael

Hi Rafael,

To model a project with no debt, on the Financial Parameters page, choose the Debt percent option set the percentage to zero. Be sure to also set the debt closing costs to zero. Be sure to also consider the costs for construction financing interest and reserve accounts and adjust those as necessary for your project. (If the debt percent is zero, the debt service reserve account will come out to zero.)

I am not sure of the best way to model this $/kW payment. Aside from the capacity payment I mention above, you could also use the capacity based incentive (CBI) on the Incentives page.

I would recommend trying different approaches and carefully reviewing the cash flow on the Cash Flow tab of the Results page to see if the results are what you expect.

SAM does differentiate between the PV system capacity in kW, and the battery capacity in kW and kWh for installation and operating costs, but it does not provide options for distinguishing between PV and battery capacity or generation for revenue calculations so you will have to find a creative solution to model your situation.

Best regards,
Paul.

Hi Paul,

Thank you very much for your email!
I think I got a handle on the capacity payments and adjusted the amount to achieve the value I was looking for.
I also put the debt to 0%, as suggested.

How does SAM estimates reflection losses? I'm trying to adjust, and or understand the amount shown.

Best Regards,

Rafael

Hi Rafael,

For PV module cover reflection losses, see Chapter 7 of Gilman, P.; Dobos, A.; DiOrio, N.; Freeman, J.; Janzou, S.; Ryberg, D. (2018) SAM Photovoltaic Model Technical Reference Update. 93 pp.; NREL/TP-6A20-67399. ( PDF 1.8 MB )

For a list of this and other PV model references, see sam.nrel.gov/photovoltaic/pv-publications.html .

Best regards,
Paul.