PySAM

7.1.1.post1 verified Fri May 01 auth: no python

PySAM is a Python wrapper for the National Renewable Energy Laboratory's System Advisor Model (SAM), enabling simulation of renewable energy systems including PV, wind, battery storage, and CSP. Version 7.1.1.post1 supports SAM version 2024.11.21. Release cadence follows SAM releases (2-3 per year).

pip install nrel-pysam

Common errors

error ModuleNotFoundError: No module named 'PySAM' ↓

cause Package not installed or installed as 'nrel-pysam' but import as 'PySAM' (case-sensitive).

fix

Run pip install nrel-pysam and ensure import uses capital 'P' and 'S': import PySAM.

error AttributeError: 'PySSC' object has no attribute 'execute' ↓

cause Direct call to PySSC object instead of a module (e.g., Pvwattsv8) that has execute().

fix

Create a module via default() or new() and call execute on that module, not on PySSC.

error TypeError: 'NoneType' object is not subscriptable ↓

cause Accessing outputs before calling execute().

fix

Ensure system_model.execute() is called before accessing system_model.Outputs.

error KeyError: 'solar_resource_file' ↓

cause Trying to assign to an input using legacy string-based method like `module.value('solar_resource_file', 'path')` which is no longer supported.

fix

Use proper attribute access: module.SolarResource.solar_resource_file = 'path'.

Warnings

gotcha PySAM modules have two layers: the DataSet (inputs) and the Outputs (results). Direct attribute assignment on the module object after `execute()` may override inputs instead of reading outputs; always access outputs via `module.Outputs`. ↓

fix Use `system_model.Outputs.annual_energy` not `system_model.annual_energy`.

gotcha Calling `module.value('param')` or `module.assign('param', val)` is legacy and fails in v7+. Use property access: `module.SolarResource.solar_resource_file = 'path'`. ↓

fix Use dot notation for inputs: `module.SolarResource.solar_resource_file = 'path'`.

gotcha The `default()` method does not automatically call `execute()`. Many users forget to call `execute()` and then inspect outputs that are still None. ↓

fix Call `system_model.execute()` after setting inputs.

breaking In PySAM v7, the `pvwattsv7` module was removed. Code using `import PySAM.pvwattsv7 as pv7` will fail. ↓

fix Migrate to `Pvwattsv8` (note capital P). See migration guide in docs.

deprecated The `Singleowner` and `Thirdpartyownership` financial models are deprecated in favor of the unified `Cashloan` model. ↓

fix Use `Cashloan` instead: `from PySAM.Cashloan import Cashloan`.

Imports

PySSC
wrong
```
import PySSC
```
correct
```
import PySAM.PySSC as PySSC
```
PySSC is a submodule of PySAM
Pvwattsv8
wrong
```
import Pvwattsv8
```
correct
```
import PySAM.Pvwattsv8 as Pvwattsv8
```
Modules are nested under PySAM package

Battery

wrong

from PySAM.Battery import Battery as BatteryModel

correct

from PySAM.Battery import Battery

Class name matches module name, collision avoided via direct import

CustomGeneration

wrong

import PySAM.CustomGeneration

correct

from PySAM.CustomGeneration import CustomGeneration

Must import the class, not just the module

Quickstart

Run a default PVWatts simulation and print annual energy. Replace 'file.csv' with a solar resource file.

import PySAM.Pvwattsv8 as pv
# Create default system
system_model = pv.default('FlatPlatePV-NoSDK')
# Modify parameters
system_model.SolarResource.solar_resource_file = 'file.csv'
system_model.execute()
print(system_model.Outputs.annual_energy)