Sensitivity Analysis

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Macro "Subarray Layout Optimization" Question


I'm simulating a system on SAM for a desired array size of 6362.35 kWdc. If I check the button "Estimate subarray 1 configuration", the resulting system (33 panels in series x 838 in parallel) has a size that I know does not fit in my area, because of the number of strings in parallel.

I found out that the macro "Subarray Layout Optimization" could optimize the layout given my area constraint. However, when I try running it the following error occurs:

Macro did not finish.
[810] referencing unassigned variable:modules_per_string_npv

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Jan Gershoj
ReOpt (Lite) functionality into SAM


Any plans to get the functionality of ReOpt into SAM?
In other words, the possibility of directly simulating optimal PV Size based on uploaded load profile.


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Offshore BOS variables for statistical analysis

Hello, I have some question regarding offshore balance of system variables for statistical analysis as listed below.

1. Are offshore BOS variables not available for input to parametric/stochastic analysis?

2. most of offshore BOS variables shows non-relevance to tornado chart output such as levelized costs and total installed costs even with extreme change (up to 100%) of input variables, is this already known problem and any way to fix it?


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Solar + Storage Optimization


Looking to design a solar + solar system around meeting a particular building load. I have the specs for the storage device/pv plant/location and load profile. Is there a way to optimize such that I can figure out the most appropriate pv and storage size and dispatch characteristics?Currently I am just seeing the ability to size each system myself - looking for the system size to be optimized (to minimize total cost). While there may be a few extreme situation to buy power from market - looking for joint system to be able to supply 100% of the load.

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Tower height not reported in parametric study

I put together a basic 100MWe power tower. I checked the boxes for Always Optimize and Always layout automatically.

When I run specific cases of various mirror slope errors, the system optimizes and the tower height changes, due to the need of more heliostats (larger field) when poor slope error.

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Impact of “analysis period’ on “required PPA” results

Modeling a PV system
I’ve been surprised by the new version of SAM determining that a higher PPA rate is required to solve for a given IRR when the analysis period is longer.
All other things being equal, I expect a lower required PPA rate to meet financial requirements when the initial costs are constant and the income is derived over a longer period. I find the expected result using the previous version of SAM (2013.9.20), but I get the opposite result from the current version (2015.1.30).

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Constant weather inputs but non-steady state gross output

Hello Paul

Could you help with the following query please regarding constant weather inputs but non-steady state gross power output?

Table 1 below shows the input for SAM that is kept constant for every hour. Table 2 shows a sample of a daily cycle from SAM's output that is the Gross Power Output.

I assume that SAM recognises the constant inputs and adjusts the DNI to follow an idealised daily cycle based on the time, latitude, longitude and elevation of the site.

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Sun tracking for static PV


What is the sun tracking value for a static PV system. I know that in the help file it says 100% is for no tracking but it is not correct. It has no sense because if you lower the value then you get a more aproximate value.

You can see this by using other PV simulation softwares.

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Anonymous Jerk
Is there a clear explanation of Packing Factor (an option in the solar Array page)?

Hi all,

In SAM's PV simulation, the Array page has a section on Land Area, which is largely determined by a packing factor. The default on SAM is 2.5, but this explanation (p6) seems counter to the default.

How does SAM consider the packing factor value? And how should we calculate it for a simple, fixed-axis roof mount?

Many thanks!

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