Electrical BOS components included in the PPA model

I am modelling a 35 MW AC PV plant using the single-owner PPA model. I am trying to use the relative values from the NREL PV + Storage Cost Benchmark Q1 2021 (Table 3 and Figure 11) to populate the Installation Costs in SAM for a system in South Africa.  I need to include the costs for the new substation and transmission line needed to make the interconnection to a nearby transmission line. If I use the 0.09 cents for Electrical BOS  in SAM (taken from Figure 11 for 50 MW single-axis tracker), can I assume that includes the average price for the substation and interconnection hardware + installation? Or rather should I include this additional cost as part of the 'grid interconnection' input under the indirect costs? Is this input meant to reflect the cost of the interconnection only, exclusive of the necessary hardware? 

I don't see any other place to include the hardware cost of a substation explicitly in the SAM model. The details in Table 3 of the cost benchmark report don't clearly list the transformers, feeders, or control room needed for the substation. I want to avoid double counting the cost of the substation in the model. This may be a better question for the authors of the benchmark study. 

Hi Lawrence,

You're on the right track to research the cost studies for an answer to this question. SAM's cost categories are at a relatively high level, so don't include details like interconnection hardware. You can decide how you want to assign different costs to the categories. In the end, it's the total installed cost that SAM uses in the cash flow calculations.

SAM's default costs are intended as a starting point for your analysis, so you should modify the costs as appropriate based on your research.

Best regards,
Paul.

Best regards,
Paul.