PV model financial parameter questions

Hello, 

I simulate detailed PV & distributed commercial model and have some questions here. 
At the financial parameter section, there are federal (21 %) and state (7 %) income tax rate. 1) Which year was used for these rate? and 2) state income tax rate is national average value?
Also, at the electricity rate section, 3) how does the 'fixed monthly charge' work in simulation and what is the impact of it? The fixed monthly charge varies depending on the electricity rate but I am not clear how does work for the results such as electricity bill, or LCOE energy costs, or NPV.
Also, 4) sometimes I have NaN value for the payback period, and what makes this result?
My last question is that the electricity load is automatically loaded based on the electricity rate that I choose? 

Very appreciate your help. Thanks

   

HI Soojin Shin,

The federal and state income tax rates are inputs. For the Commercial financial model, SAM uses these tax rates to calculate the value of any tax credits from the Incentives input page and of accelerated depreciation benefits as defined on the Financial Parameters input page. You can see the effect of these tax rates on the Cash Flow tab of the Results page. The income tax rates apply in each year over the analysis period. You can use the blue and gray "Value/Sched" button to change the tax rate by year.

For more about the income tax rate inputs, see the Help topic for the Financial Parameters page (click Help or press the F1 key). Here is a link to a web copy of that Help topic: samrepo.nrelcloud.org/help/fin_commercial.htm

For more about the "Value/Sched" button, see The "Edit Data Table by Column" Help topic under "Reference:" samrepo.nrelcloud.org/help/edit_data_table_column.htm

The default value of the federal and state income tax rates (21% and 7%, respectively) are placeholder values that you should change as appropriate for your analysis. Income tax rates vary widely by project owner and state.

The fixed monthly charge on the Electricity Rates is a fixed charge that the system owner pays on their monthly electricity bill. The total monthly bill is the sum of the fixed charge, energy charge, and demand charge, with adjustments as appropriate for excess generation (net metering, net billing, etc.). You can read more about that in the "Electricity Rates" topic ( samrepo.nrelcloud.org/help/electricity_rates.htm ) and Electricity Bill Results ( samrepo.nrelcloud.org/help/utility_bill_results.htm ) Help topics.

 

SAM uses the annual electricity bill to determine the value of the electricity generated by the system: The value of electricity savings in the project cash flow is the difference between the electricity bill without system and electricity bill with system. These savings affect the project net present value (NPV), but not the levelized cost of energy (LCOE). The NPV represents the value of the system, accounting for all project costs, taxes and incentives, and financing. The LCOE represents the cost of the system over its lifetime. See these topics in the "Financial Metrics" chapter of Help:

samrepo.nrelcloud.org/help/mtf_npv.htm

samrepo.nrelcloud.org/help/mtf_lcoe.htm

The value "NaN" means "not a number." The payback period is not a number when its value is greater than the analysis period:

samrepo.nrelcloud.org/help/mtf_payback.htm

The electricity load data is an input. You must provide a times series (hourly or sub-hourly) profile representing the system owner's electricity usage for one year. SAM does not automatically change the load based on other inputs:

samrepo.nrelcloud.org/help/electric_load.htm

Best regards,
Paul.