The SAM web site will be upgrading Monday, May 23 from 4:00-5:00pm (Denver/mountain time). 

After doing a major change to our infrastructure, we have found a minor issue that we have corrected but will need to reboot the web site for it to take affect.

To make it as convenient as possible, we have scheduled it for Monday, May 23rd at 4:00pm (mountain). The process takes 15-20 minutes, but the site will only be unavailable for a short time. However, your session information will be lost (eg if you're writing a post, what you have written could be lost). 

Detailed Photovoltaic Model

Photovoltaic Reference Manual

Gilman, P.; Dobos, A.; DiOrio, N.; Freeman, J.; Janzou, S.; Ryberg, D. (2018) SAM Photovoltaic Model Technical Reference Update. 93 pp.; NREL/TP-6A20-67399. (PDF 1.8 MB)

Gilman, P. (2015). SAM Photovoltaic Model Technical Reference. National Renewable Energy Laboratory.  59 pp.; NREL/TP-6A20-64102. (PDF 1.8 MB)

Errata for 2015 Edition of PV reference manual, 4/7/2017 (PDF 111 KB)

Module Models

CEC Module Model

Dobos, A. P. (2012). An Improved Coefficient Calculator for the CEC Photovoltaic Module Model. ASME Journal of Solar Energy Engineering. 6pp. Volume 134 No.2.

De Soto, W.L. (M.S. 2004). Improvement and Validation of a Model for Photovoltaic Array Performance. University of Wisconsin-Madison. (ZIP 1.8 MB)

Sandia Module Model

King, D.L.; Boyson, W.E.; and Kratochvil, J.A. (2004). Photovoltaic Array Performance Model. 41 pp.; Sandia Report No. 2004-3535. (PDF 1.8 MB)

IEC 61853 Module Model

Dobos, A.; Freeman, J. (2017) Significant Improvement in PV Module Performance Prediction Accuracy using a New Model Based on IEC-61853 Data. Photovoltaic Specialist Conference (PVSC), 2017 IEEE PVSC-44. (PDF 272 KB)

Dobos, A. P. (2015).  Procedure for applying IEC-61853 test data to a single diode mode. Photovoltaic Specialist Conference (PVSC), 2014 IEEE 40th.

Simple Efficiency Module Model

See Gilman (2015) PV reference manual cited above.

Inverter Models

Inverter CEC Database Inverter Model (Sandia Inverter Model)

King, D.L.; Gonzalez, S.; Galbraith, G.M.; and Boyson, W.E. (2007). Performance Model for Grid Connected Inverters. 47 pp.; Sandia Report No. 2007-5036. (PDF 1.3 MB)

Inverter Datasheet and Inverter Part Load Curve Models

See Gilman (2018) PV reference manual cited above.

Plane-of-array (POA) Irradiance

Bifacial Modules

DiOrio, N.; Deline, C. (2018). Bifacial Simulation in SAM. Presented at Bifi PV 2018 Workshop, Lakewood Co. NREL/PR-6A20-72360 (PDF 1 MB)

Marion, B.; MacAlpine, S.; Deline, C.; Asgharzadeh, A.; Toor, F.; Riley, D.; Stein, J.; Hansen, C. (2017). A Practical Irradiance Model for Bifacial PV Modules. NREL/CP-5J00-67847 (PDF 1 MB)

One-axis Tracking

Marion, W.; Dobos, A. (2013). Rotation Angle for the Optimum Tracking of One-Axis Trackers. National Renewable Energy Laboratory. 10 pp.; NREL/TP-6A20-58891. (PDF 388 KB)

Partial Shading of Photovoltaic Array

MacAlpine, S.; Deline, C. (2015) Simplified Method for Modeling the Impact of Arbitrary Partial Shading Conditions on PV Array Performance. National Renewable Energy Laboratory. 8 pp.; NREL/CP-5J00-64570. (PDF 699 KB)

Deline, C.; MacAlpine, S.; Hanson, A.; Stauth, J.; Sullivan, C. (2015) Partial-Shading Assessment of Photovoltaic Installations via Module-Level Monitoring. National Renewable Energy Laboratory. 7 pp. NREL/CP-5J00-63765. (PDF 816 KB)

POA Irradiance as Input

Freeman, J.; Freestate, D.; Hobbs, W.; Riley, C. (2016). Using Measured Plane-of-Array Data Directly in Photovoltaic Modeling: Methodology and Validation. National Renewable Energy Laboratory. 6 pp. NREL//CP-6A20-66465. (PDF 1.4 MB)


The NREL Soiling Map provides information about soiling parameters in the United States with a list of publications describing NREL research on soiling of photovoltaic modules.

Terrain Slope

Anderson, K.; Mikofski, M. (2020) Slope-aware Backtracking for Single-axis Trackers. National Renewable Energy Laboratory. 24 pp. NREL/TP-5K00-76626. (PDF 783 KB)

Module/Cell Temperature Models

Prilliman, M.; Stein, J. S.; Riley, D.;  Tamizhmani, G. (2020). Transient Weighted Moving-Average Model of Photovoltaic Module Back-Surface Temperature. IEEE Journal of Photovoltaics. 8 pp. Volume 10 No. 4. 

Neises, T. (M.S., 2011). Development and Validation of a Model to Predict the Temperature of a Photovoltaic Cell. University of Wisconsin-Madison. (ZIP 4.4 MB)

DC Losses

Self Shading

Deline, C.; Dobos, A.; Janzou, S.; Meydbrey, J.; Donoval, M. (2013). A Simplified Model of Uniform Shading in Large Photovoltaic Arrays. Solar Energy Vol 96, October 2013, pp 274-282. Draft Preprint (PDF 1.3 MB)

Subarray Mismatch

Dobos, A. P. (2012). Modeling of Annual DC Energy Losses due to Off Maximum Power Point Operation in PV Arrays. [Proceedings] 38th IEEE Photovoltaic Specialists Conference (PVSC '12), 3-8 June 2012, Austin, Texas. Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE) pp. 002967-002969; NREL Report No. CP-6A20-55362.

Snow Coverage

Ryberg, D.; Freeman, J. (2017).  Integration, Validation and Application of a PV Snow Coverage Model in SAM. National Renewable Energy Laboratory. 33 pp. TP-6A20-68705. (PDF 3.1 MB) This is an update to the 2015 paper.

Ryberg, D.; Freeman, J. (2015). Integration, Validation and Application of a PV Snow Coverage Model in SAM. National Renewable Energy Laboratory. 21 pp. TP-6A20-64260. (PDF 2.1 MB)

Power Electronics

Freeman, J. (2015). Modeling Photvoltaic Module-Level Power Electronics in the System Advisor Model. National Renewable Energy Laboratory. 2 pp. FS-5400-64113 (273 KB)

Model Comparison

Yates, T.; Hibberd, B. (2010). Production Modeling for Grid-Tied PV Systems. SolarPro (Issue 3.3 Apr/May).


Note: The PVWatts website uses a different version numbering system than the PVWatts model. For example, the website "Version 6" uses the PVWatts Version 5 model.

Dobos, A. (2014). PVWatts Version 5 Manual. 20 pp.; NREL Report No. TP-6A20-62641. (PDF 714 KB)

Dobos, A.; (2013). PVWatts Version 1 Technical Reference. 11 pp.; NREL Report No. TP-6A20-60272. (PDF 487 KB)

Marion, B.; Adelstein, J.; Boyle, K.; Hayden, H.; Hammond, B.; Fletcher, T.; Canada, B.; Narang, D.; Shugar, D.; Wenger, H.; Kimber, A.; Mitchell, L.; Rich, G.; Townsend, T. (2005). Performance Parameters for Grid-Connected PV Systems. 9 pp.; NREL Report No. CP-520-37358. (PDF 816 KB)

Fuel Cells

DiOrio, N.; Janzou, S. (2019). DRAFT. Fuel Cells in SAM: User Guide. (PDF 466 KB)