Recent and planned improvements to the System Advisor Model (SAM)

1. NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.
Recent and Planned Improvements
to the System Advisor Model (SAM)
4th Photovoltaics Modeling Workshop
Aron P. Dobos
23 October 2015

2. 2
System Advisor Model (SAM)
• Combines detailed performance and financial models to estimate the cost
of energy for systems
• Free: http://sam.nrel.gov/download
• Models are country-agnostic

3. 3
What’s new in SAM for PV?
• PV-coupled battery energy storage for lithium
ion and lead acid systems
• Lifetime simulations of PV systems for 30 years
at subhourly timesteps
• Diffuse shading losses calculated from 3D scene
• PV module model using IEC-61853 test data

4. 4
New Battery Model
• Designed for behind-the-meter analysis (residential and
commercial scale systems)
• Lithium ion and lead acid chemistries including submodels
for cell voltage, capacity, thermal, degradation, and
replacements
• Highly configurable manual dispatch controller
• Integrated with PV system lifetime analysis to capture
economic effects of capacity degradation and costs of
replacement
• Incentives, complex utility tariff structures, and financing
costs included in analysis.
• Validated with laboratory measured test data for two
systems.

5. 5
Storage Dispatch and Degradation
Battery meets portion of load
during peaks
4 kW PV system
2 kW peak load
Battery replacements
result in additional costs
User input degradation with
cycling and depth-of-discharge

6. 6
Lifetime Simulations
In this mode, PV system degradation is (correctly) applied to the DC output of the PV
modules, and so can be used to assess inverter clipping levels as the system effective
sizing ratio changes in time.
When the system is new, much more DC power is generated than inverter capacity,
resulting in significant clipping. As the modules degrade and produce less power,
clipping is reduced in the later years of the system
DC power
AC power
(30 years)

7. 7
3D Shading Model
• Fully integrated into SAM
• Calculates linear beam shading
losses and sky diffuse view factor
loss
• Imports 2D mapping underlays
from Bing maps
• Diurnal or hourly/subhourly time
series shade simulation
Upcoming new features:
• Estimation of nonlinear losses for
shaded parallel strings
• Scripting to automate panel layout
and import/export geometry data

8. 8
IEC-61853 Module Model
Dobos, A.; MacAlpine, S. Procedure for Applying IEC-61853 Test Data to a Single Diode Model.
Proc. IEEE 40th PVSC Conf. Denver CO, June, 2014

9. 9
Other Recent SAM Improvements
• New user interface (November 2014)
and native Linux version
• Added various metering (net, non-net,
etc) options for complex utility bill
calculations
• Batch simulations run in parallel on
multiple processors for parametric and
stochastic options
• Added a simplified LCOE calculator
based on a FCR
• 1600+ weather files included by
default in CSV format
• Expanded scripting capabilities and
new language support in SDK for PHP
Linux x86-64 !

10. 10
Planned Upcoming Capabilities
• Option to input measured POA data for PV simulation
(matched reference cell or broadband options)
• Automatic dispatch strategies for battery model
including peak shaving, power limiting, others.
• Multiple input MPPT inverters
• New options for transient PV thermal models appropriate
for short timestep modeling
• Calculation of nonlinear shading losses in systems with
parallel strings based on method of Deline & MacAlpine
(PVSC 2015)
• Validation and intercomparison of various 3D shading
loss models

11. 11
Questions
SAM Team 2015
Aron Dobos – Technical lead and project management
Nate Blair – Emeritus lead, on assignment to the World Bank
Janine Freeman – Photovoltaics, validation, and wind systems
Nick DiOrio – Battery systems
Paul Gilman – User support and documentation
Steve Janzou – Programming and financial models
Ty Neises – CSP models
Mike Wagner – CSP models
Severin Ryberg – Intern
This work is supported by the US Department of Energy SunShot program.
http://sam.nrel.gov/download