Change Log

This page lists versions of SAM with significant changes for each version. You can download the current and legacy versions of SAM from the Downloads page.

For a detailed list of changes with potential impact on results, see the Release Notes, which are available on SAM's Help menu.

SAM 2014.1.14 January 2014

This is a maintenance update to version 2013.9.20.

  • Fixed a bug for the photovoltaic models with southern hemisphere weather files with the "Tilt=Latitude" option enabled that caused SAM to generate a simulation error message.
  • Fixed a bug for the PVWatts system model with 1-axis tracking. The bug caused the model to enable backtracking with a GCR of -1. This caused unrealistic results for a few hours of the year, but did not noticeably affect the system’s total annual output.
  • Corrected the Flat Plate PV model's inverter library entry for the Toshiba (TMEIC) 500U. The correct values for the voltage and current ratings are: Vdcmax = 600 V, Idcmax = 1600 A, MPPT low = 320 V, and MPPT high = 550 V.
  • Updated the CEC inverter library to the January 2014 version.
  • Fixed a mistake in the PDF report for photovoltaic models with Commercial PPA, Utility IPP, or Single Owner financing in "Specify PPA Price" mode to show meaningless symbols for the PPA price value. This issue does not affect values that appear in the SAM user interface -- it only affects the PDF report.
  • Changed the Flat Plate PV default assumption on the Array page for ground reflectance to not use the albedo value from the weather file by default because the albedo values in the standard weather files tend to be unreliable. By default, SAM uses the 0.2 value specified in the monthly albedo input table instead of reading hourly values from the weather file.
  • Fixed a bug in the energy loss diagram for concentrating solar power models (CSP) with a large portion of the thermal energy to the power block supplied by the fossil backup system that caused the energy loss diagram to display an incorrect value for the "System Output to Grid" quantity.
  • For the linear Fresnel model, fixed an issue with the the collector azimuth angle variable on the Solar Field page being disabled with the collector incidence angle table option on the Collector and Receiver page.
  • Fixed an issue that caused the power tower model with thermocline storage to report an incorrect warning about the storage fluid temperature being outside of its operating range.
  • For the physical trough model, fixed some problems that caused simulations to fail for low temperature applications. The evacuated tube convergence algorithm could fail to converge when the DNI is zero and the HTF is losing energy to its surroundings,  and some of the property lookup routines failed when field temperatures fell below zero degrees Celsius.
  • For the physical trough and generic solar system concentrating solar power models Thermal Storage page, fixed the units in the thermal storage capacity label. The correct units are MWht, not MWt. This is a mistake in the user interface label and does not affect simulations.
  • Fixed a mistake in the Linear Fresnel PDF report that showed aperture area of a single collector instead of the total aperture area.
  • Updated the TRNSYS source code files.
  • Fixed a bug for the residential and commercial financial models, that caused SAM to apply the "percent of annual output" factor from the Performance Adjustment page twice.
  • For the residential and commercial financial models with net metering, corrected the Sales/Purchases without System value for January. (The values for February through December were correct.) This caused the Net Savings with System value in the Metrics table to be incorrect.
  • For the residential and commercial financial model results, corrected the monthly "Energy Rate Charge in [mmm] ($)" label, and added the missing "Year 1 monthly sales/purchases without system ($)" variable is missing. The label should be "Energy Charge in [mmm] ($)."
  • For the residential and commercial financial models with the "Normalize supplied load profile to monthly utility bill data" option on the Electric Load page enabled, SAM used the original, non-normalized peak load to calculate monthly demand charges. With this update, SAM uses the normalized peak load values to calculate the demand charges. Although the old behavior is appropriate with 10- or 15-minute load data when the magnitude of the normalized data is similar to the original data and you want to preserve the original peak values, we decided to change it because it may be unexpected behavior, and is not appropriate when you normalize the load to much higher or lower magnitudes than the original data.
  • Fixed the formula in the cash flow spreadsheets with equations for residential and commercial financial models to correctly calculate state ITC amount. The formula in Cell B51 was incorrect.

SAM 2013.9.20 September 2013

  • Fixed an issue on OS X systems when editing the library and weather file search path.
  • Updated utility rate inputs to be compatible with Version 2 of the OpenEI Utility Rate Database. For each utility in the database, SAM groups rate structures by category to make it easier to find a specific structure.
  • Net metering algorithm now carries over monthly credits and applies an optional year end sell rate. (Older versions of SAM assumed used hourly accounting for net metering.)
  • Renamed hourly and monthly results variables, and removed duplicate and confusing variables.
  • Added two options to model photovoltaic inverters not in the Sandia inverter database: The "datasheet" option allows you to enter parameters from a manufacturer datasheet. The "part load curve" option allows you to enter part-load efficiency curve that is linearly interpolated across the range of operation.
  • For photovoltaic self-shading shading of 1-axis trackers, a new ground coverage ratio input replaces the row width and spacing inputs to avoid being able to model systems with inconsistent array layout inputs.
  • Added estimation of a photovoltaic system's output reduction due to self-shading of 1 axis trackers using an approximation that calculates geometric beam irradiance shading fraction from the GCR and assumes a “long” row. The diffuse sky and reflected irradiance is also reduced based on the view factor reduction to adjacent rows. Note: does not currently model nonlinear impact of electrical mismatch losses
  • Added additional detail in the photovoltaic energy loss diagram to better characterize the source of each loss: irradiance reductions due to shading, inverter operation and clipping, and others.
  • Improved labeling of photovoltaic model results variables.
  • Bug fix to photovoltaic backtracking algorithm for 1-axis trackers: The rotation angle limit is now applied correctly for backtracked systems.
  • Bug fix in photovoltaic fixed tilt system self-shading code: The diffuse irradiance view factor reduction calculations were modified slightly to more accurately characterize the light blocking on the array.
  • Added an option in PVWatts to change the mounting configuration of the PV array. The selection of an open rack or roof-standoff mounting system adjusts the installed nominal operating cell temperature (INOCT) of the modules in the system.
  • Replaced the solar water heating performance model with a faster model.
  • Concentrating solar power physical trough, power tower, direct steam tower and linear Fresnel: Fixed an error in the powerblock startup calculations. This isn't a problem for simulations where the startup time is less than the simulation timestep, so the default cases (direct steam power tower & linear Fresnel) that use this model are not affected. Models where the startup time is greater than the simulation time may have been underpredicting the required startup energy.
  • Concentrating solar power physical trough, power tower, direct steam tower and linear Fresnel: Corrected an error in the hybrid cooling model that decreases annual results using hybrid cooling model between by as much as 0.5% for the Molten Salt Tower and 1.75% for the Physical Trough model. These are worst case differences at small wet cooling fractions. Larger wet cooling fractions result in smaller differences.
  • Concentrating solar power dish Stirling: Fixed a significant bug that underestimated shading losses in the default dish Stirling model. The annual energy in the default case decreases by 6.5%. As the spacing between modules increases, the difference between the old and new codes decreases and eventually disappears.
  • Concentrating solar power empirical trough and the generic solar system model: the turbine startup energy calculation was not properly deducting energy for systems without thermal energy storage and with a large turbine thermal startup requirement. For these cases, the error in annual output could be greater than 12% (output went up after the fix), depending on the power block startup energy requirement. The impact for the default values in both the GSS and Empirical trough was minimal.
  • Concentrating solar power generic solar system model: the optical efficiency table is accompanied by a checkbox indicating whether the table should be interpolated or should simply return the nearest value. The checkbox values were backwards – i.e. checking “interpolate” actually caused the model to return the nearest value, and vice versa. This bug would be most significant in cases with significant optical efficiency variation over small changes in the angular inputs, or in tables with a small number of values that differ substantially from each other. For the default case, change in annual output was less than 1%.
  • The powerblock model for the concentrating solar power physical trough and molten salt power tower models was not correctly accounting for powerblock startup times greater than 1 hour (note the default is 0.5). The fix will cause annual energy output to decrease for these cases. For example, in the molten salt power tower, using the defaults and changing the powerblock startup time to 1.5 hours decreases the annual energy by about 4%. This bug will also affect custom simulations using timesteps less than the powerblock startup time.
  • Improved TRNSYS convergence of concentrating solar power molten salt power tower during periods when the solar field is off but storage and the powerblock are still operating. The default case shows around a 0.2% increase in annual energy, and an elimination of TRNSYS convergence errors reported in the log file.
  • Improved startup and pumping power calculations in concentrating solar power direct steam power tower. Default case annual energy increases around 0.8%.
  • Fixed bug in concentrating solar power air cooling model that caused fan parasitics to switch to 0 in some cases where it was operating. The fixed version reduces the default power tower models annual energy output around 1%.
  • Added function to import a user defined turbine layout for a wind farm.
  • Added two new wake effect models for wind farms: Park (WAsP) and Eddy-Viscosity.
  • Worked with Mistaya Inc to develop the capability for Windographer software to export data in SAM’s .srw wind resource file format.
  • Increased the maximum number of turbines that can be analyzed in a wind farm from 250 to 300.
  • Added a capability to display information about siting considerations for a particular location. SAM communicates with the NREL Wind Prospector online tool to obtain the information.
  • Fixed a bug in the geothermal model where certain calculation were not updated during parametric runs.
  • Fixed a bug in the geothermal model that caused SAM to calculate the temperature drop for an EGS resource incorrectly.

SAM 2013.1.15 January 2013

This version is an update to SAM 2012.11.30 and does not introduce any new features.

  • Fixed an issue that caused SAM to stop responding when viewing SRW wind data files with invalid format.
  • Updated Performance Adjustment variable group names so they appear correctly in lists of variables (parametrics, etc.).
  • Resized boxes on input pages to fit notes in orange font.
  • Fixed an issue with the advanced utility IPP financial models that prevented the model from converging when the LCOE was very small.
  • Fixed an issue with the cash flow Send to Excel feature that that caused percentages to be incorrectly displayed in Excel, and caused inaccurate escalation rate calculations.
  • Disable Excel Exchange by default.
  • Fixed a problem with TOU adjustment rates issues with net metering and load.
  • Made the utility rate database window resizable and added scrollbars to make it easier to see long names and descriptions.
  • Fixed a problem with cash flow graphs in reports for the advanced utility IPP financial models that caused multiple bars to appear on the graph.
  • Fixed a problem with the weather data reader so that it correctly exports data headings.
  • Fixed a problem with the Save with Hourly Options result that prevented SAM for saving data with unusual numbers of values (e.g., 200 values for statistical simulation).
  • SAM now prompts you for a folder to save reports, and uses the .zsam file location by default instead of automatically saving it in the user folder without any feedback.
  • SamUL PtOptimize() script function returns true/false depending on whether solar field optimization was successful.
  • Added SamUL PtGetOutput() script function to return all messages from running PTGen via PtOptimize()
  • Flat plate PV did not read shading inputs for Subarray 1.
  • Updated report templates for PV systems to correct formatting and logic issues.
  • Flat plate model now correctly imports azimuth angle value from files saved with SAM 2011.12.2.
  • Fixed HCPV system costs page icon in navigation menu.
  • Fixed tab order on photovoltaic input pages.
  • Removed parentheses in photovoltaic model results labels so they appear correctly in the time series data viewer.
  • Update TRNSYS source code files for all CSP models
  • Fixed a problem with the empirical trough model when the solar field stow angle was 180 degrees.
  • Fixed bug that results in Empirical trough model annual output error of 4%.
  • Improved input variable labels on Solar Field page for “exact area" and “actual aperture.”
  • Fixed issue with empirical trough model solar field initial temperature. This had a very small impact on the system's total annual output.
  • Fixed a problem for the wind cost model that caused values to be zero.
  • Corrected the wind PTC default value.
  • Added a limitation of 300 turbines to the total number of turbines in a system with an error message when more turbines are entered into the farm layout.
  • Fixed a problem with energy values shown in the Geothermal report.
  • Fixed a problem with the energy loss diagram that caused labels to overlap.

SAM 2012.11.30 November 2012

  • Automatically download incentive data from DSIRE database
  • SAM solar wizard for PVWatts, Empirical Trough, and Solar Water Heating models
  • Loss diagram
  • Export cash flow to Excel with formulas
  • More rates in utility rate database from OpenEI
  • New month by hour performance adjustment factors
  • New report templates
  • Reorganize navigation menu and input pages, especially for Financial models
  • Remove graph sliders and optimization analysis option (parametric option is a better way to show variation of results over a range of inputs)
  • Update default values, including changing default analysis period from 30 to 25 years
  • PVWatts: Force Tilt = Latitude option sets tilt angle to absolute value of latitude so it works for southern hemisphere
  • PVWatts: Generate error for invalid weather data
  • Flat Plate PV: Subarray modeling with up to four subarrays
  • Flat Plate PV: Report relative air mass in hourly results
  • Flat Plate PV: Calculate system performance factor consistently with CPV model
  • Flat Plate PV: Specify DC and AC derate factors as fractions instead of percentages to be consistent with PVWatts
  • Flat Plate PV: Update module and inverter databases
  • Flat Plate PV: Corrected issue where Single Point Efficiency inverter model reported system output equal to inverter nameplate capacity for some hours of zero radiation
  • Flat Plate PV: Sandia module model reports module temperature as equal to ambient temperature (instead of zero) during nighttime hours (no effect on results)
  • Flat Plate PV: Corrected issue with nighttime inverter parasitic losses not being correctly deducted from system's total output
  • High-X Concentrating PV: Specify tracker power as fraction of nameplate capacity instead of fixed power so tracker parasitic power scales with system size
  • High-X Concentrating PV: Update inverter database
  • CSP: Update HTF fluid library, and add Therminol 66 and 59 fluids for trough models
  • CSP: Allow heliostats on x axis for molten salt power tower model
  • CSP: Correct runner and header heat loss calculation
  • CSP: Change absolute pipe roughness in power tower models from 1.5E-5 to 4.5E-5 meters
  • CSP: DELSOL flux map uses normalized values at each node
  • Wind: Turbine input page allows choice between turbine library and turbine parameters
  • Wind: Location Lookup downloads data from NREL Eastern Wind Dataset in addition to Western Wind Dataset
  • Wind: New typical wind data files for representative locations in U.S.
  • Wind: System costs page uses NREL Capital Cost model for onshore and offshore wind farms
  • Biopower: Access to DOE Billion Ton update for dedicated energy crops
  • Biopower: New life-cycle emissions model
  • Geothermal Power: Plant cost estimates for binary geothermal units

SAM 2012.5.11 May 2012

  • Improved PV simulation engine for faster simulations
  • New High-X Concentrating PV (HCPV) model replaces CPV module model option
  • Rename "Component-based PV" model to "Flat Plate PV" model
  • Change azimuth angle convention for Flat Plate PV model to match PVWatts
  • Improved PV sun angle algorithm, and backtracking and self-shading models
  • New report templates for PV, wind, biomass power, and geothermal power models
  • New lifecycle impacts analysis for biomass power model
  • Combine wind utility-scale and small-scale model into a single model that uses wind resource data from the NREL Western Wind Dataset
  • CSP thermal storage model fixes to heater parasitic loss and tank freeze protection calculations
  • Modify CSP optical efficiency calculations to include cosine effects
  • Fix empirical trough model use of collector stow angle value and storage over-discharge condition
  • Fix physical trough and molten salt power tower field defocus algorithm
  • Fix physical trough freeze protection calculation

SAM 2011.12.2 December 2011

SAM 2011.12.2 is a maintenance update that addresses a few issues with the previous version including:

  • Error when opening zsam files by double-clicking the file name.
  • Issue with power tower models in Mac version.
  • Handling of PV soiling derating factors when opening files created in older versions.

For a full description of new features in this version, see the SAM 2011.11.29 description below.

2011.11.29 November 2011

SAM 2011.11.29 adds three new technologies and several tools and capabilities, in addition to bug fixes, usability improvements, and documentation revisions

New technologies

  • CSP Linear Fresnel
  • CSP Direct Steam Power Tower
  • Biomass Power

New capabilities

  • Model PV modules with spec sheet data
  • Monthly soiling derates for PV systems
  • P50/P90 analysis
  • Model a generic system using hourly or sub-hourly generation profile as input

New tools

  • Integrated time series data viewer
  • Report Generator
  • Case Compare

Photovoltaic Component-based

  • Removed ground reflectance with snow input (albedo w/ snow) from the Array page.
  • Tilted Surface Irradiation Models: Removed the Hay & Davies, and Perez 1988 diffuse irradiation models options from the Array page.
  • Irradiance Component Input Option: Removed the option on the Array page for using total (global) horizontal and diffuse components of irradiation. The current options are total and beam, and beam and diffuse. By default, SAM uses beam and diffuse from the weather file.
  • Soiling: Added an option for entering monthly soiling derates. The derate is applied equally to all components of the calculated plane-of-array (POA) irradiance before the DC module power is calculated.
  • Shading: Added an option to import Solar Pathfinder Month x Hour or Obstruction table shading input files.
  • PV Module Model: Added a “CEC Performance Model with User Entered Specifications” option on the Module page. This model allows the user to enter module datasheet specifications directly into SAM, which calculates coefficients to drive the CEC performance model. The coefficients are calculated using a method detailed in the SAM help system.
  • PV Databases: The CEC PV Module, Sandia Module, and Sandia Inverter databases were updated to the latest available versions./
  • Monthly Soiling Derates: The PV Component-based model includes an option to specify 12 monthly values for the soiling derate factor on the Array page.
  • Backtracking: The backtracking option in SAM was temporarily removed for this version because the SAM team did not have confidence that it was working correctly in all configurations. We are developing an updated algorithm and expect it to be faster and easier to use for future versions of SAM.

Photovoltaic PVWatts

  • Cell Temperature: PVWatts in SAM now reports cell temperature as equal to ambient temperature (dry bulb) when the sun is down.
  • Handling of Snow Depth: PVWatts in SAM now uses the snow depth data in a TMY2 weather file (if available) to adjust the ground reflectance (albedo) from 0.2 (no snow) to 0.6 (with snow cover). This change makes the results match the online PVWatts V.1 exactly for TMY2 files.

Physical Trough System

  • Improved the iterative solution algorithm for solar field mass flow rate.
  • Adjusted the design-point mass flow rate in the solar field to more correctly calculate the absorbed thermal energy and thermal losses from the loop at design.
  • Updated pipe diameter sizing algorithm to correctly handle systems where the number of SCA’s in the loop is 1 or 2 (8 is the default value).
  • Potential impacts include: Addresses a bug causing the simulation to crash in this scenario.

  • Correction to header piping length calculation.
  • Added an algorithm to the solar field model that avoids recalculating the solar field during multiple iterations if the inputs to the module do not change.
  • Correction to the calculation of optical efficiency during the first and last hour of the day in which the solar field operates.
  • Optical “end loss” (light reflected at an angle off the end of the last collector in a row that is not absorbed) was previously applied as an average optical loss to each collector in the loop. The code was updated to apply this loss to only the relevant collectors in the loop.
  • Improved the solar field freeze protection algorithm.
  • Updated pressure loss calculation in the hot and cold headers to scale more accurately with mass flow rate. Potential impacts include: Reduced pumping parasitic requirement at part-load operation.
  • Improved evacuated tube receiver thermal loss model to account for the temperature gradient across the SCA instead of calculating the thermal losses at an average temperature only.
  • Potential impacts include: Improved accuracy in thermal loss calculations for the solar field receivers.

  • Removed the minimum power cycle restart requirement. The functionality of this value was compromised by the turbine startup time requirement and the turbine startup energy requirement, and thus is no longer necessary.
  • Corrected a bug in the thermal storage system that allowed a negative mass in the tank under some conditions. This caused the simulation to crash.
  • Corrected the calculation for thermal load into the power block during standby mode operation. The previous release underestimated the thermal requirement to maintain standby operation.
  • Improved steam property lookup accuracy.

Empirical Trough System

  • No changes

Power Tower System

  • Implemented a bug fix for calculating heliostat efficiency at negative solar azimuth angles. The previous release used the heliostat field component from the TRNSYS STEC library to interpolate solar field efficiency from a matrix defined by solar azimuth and zenith angles which artificially limited the solar azimuth angle to zero. The TRNSYS definition for solar azimuth angles applies a range of -180° to +180° (North to North, clockwise), thus the solar field efficiency was incorrectly interpolated at an azimuth angle of 0° for all solar azimuth angles less than zero (morning hours).
  • Added outputs to report HTF pressure drop across the receiver.
  • Removed the minimum power cycle restart requirement. The functionality of this value was compromised by the turbine startup time requirement and the turbine startup energy requirement, and thus is no longer necessary.
  • Corrected a bug in the thermal storage system that allowed a negative mass in the tank under some conditions. This caused the simulation to crash.
  • Corrected the calculation for thermal load into the power block during standby mode operation. The previous release underestimated the thermal requirement to maintain standby operation.
  • Improved steam property lookup accuracy.

Dish Stirling System

  • No changes

Generic Solar System

  • Updated the optical table interpolation algorithm to allow simultaneous interpolation of multiple tables. This change was made to support the Linear Fresnel system, which also uses the algorithm developed within the GSS model. Potential impacts include: No performance impacts are expected.
  • Improved performance calculations to determine the design-point solar field optical efficiency based on the actual solar zenith at solar noon on the summer solstice. This allows the model to choose a more representative design-point mass flow rate.

Generic System

  • SAM's Generic System model now allows you to provide either hourly generation data or sub-hourly data with up to one-minute resolution as input, which makes it possible to use results from an external performance model with SAM's financial models.

Solar Water Heating

  • Collector Specification: Updated simulator to correctly use number of collectors specified by user. Also made collector database on user interface searchable.
  • Draw Profile: Added option to scale hourly draw profile to an average daily hot water draw of kg/day.

Wind Small Scale

  • None

Wind Utility Scale

  • None

Geothermal Power

  • Removed some unnecessary inputs, and updated default values.
  • Allow pump work as input.
  • Added the power block component, which to allow for modeling of a geothermal system using SAM's power block component.

Geothermal Co-production

  • None

Biomass Power

  • The utility-scale biopower model was developed by the SAM team with internal funding from NREL. The model accesses online NREL databases of biomass resource to model a biopower plant.


  • Integrated time series data viewer. SAM's new Time Series Data Viewer replaces DView for displaying graphs of time series data. The new viewer is integrated into the user interface, and runs on both Windows and Mac OS versions of SAM. DView is still available in SAM via the Results menu.
  • Report Generator. The new report generator allows you to design and generate reports in PDF format with tables of both input data and results, along with text, and images. Once you design a report template, you can use it with different SAM files. This should facilitate generating reports for project reports.
  • Case Compare. The Case Comparison window shows inputs and results from all of the cases in a file in a single, editable table. You can quickly identify differences between cases, and update values of inputs directly from the window.
  • Search Box: For inputs that use a list to populate values (weather file, PV modules and inverters), a search box makes it possible to type a few characters of the input name.

Cost and Financing

  • Land Cost for Solar Systems: The land cost category on the System Costs page for PV and CSP systems is now linked to the land area input on the Array or Solar Field page.

Weather Files

  • Location lookup allows for choosing specific year or "typical DNI year" file. Previous versions only downloaded the typical year file.

2011.6.30 June 2011

This version includes updated default input values across all technologies and several bug fixes. Financing

  • Reorganize and rename financing options in the Technology and Market window: The Utility Independent Power Producer (IPP) option is equivalent to the Utility IPP options in pre-2011.5.4 versions of SAM, and the new utility financing options are listed under the "Advanced Utility IPP Options" heading.
  • Removed the mid quarter MACRS depreciation option from the Utility IPP and Commercial PPA options.
  • Added a custom depreciation option for the new utility financing options to facilitate analysis of depreciation schedules other than those typically available under U.S. tax law.
  • Corrected a problem with the units in the Production Tax Credit calculation that affected analyses involving the PTC. SAM 2011.5.23 and earlier incorrectly overestimated the PTC amount by a factor of 1000.
  • Fixed convergence issues in the PPA price calculation algorithm in the Utility IPP and Commercial PPA models when used with Wind, Generic, and PVWatts system models.


  • Updated CEC PV Module and Updated Sandia PV Inverter databases.
  • Corrected a problem with reading Solmetric SunEye shading files.
  • For the advanced Multiple Systems simulation option, corrected the PV capacity factor and system performance factor calculation.


  • Updated default input values across all technologies.
  • Added PDF export for single graphs.
  • Corrected a problem with SAM window placement on a multiple monitor setup.
  • Corrected a problem with axis labels in graphs of parametric results that included variable linkages. SAM now displays the value of one of the linked variables instead of using long labels that include all variable names and values.
  • Added a search box to selection windows such as the Choose Parametrics window. You can now type a few characters of a variable name to find it in the list.
  • Fixed a problem with the Mac version on some older 32-bit Mac OS systems.

Weather Data

  • Improved error checking for weather files, and in the TMY3 weather file creator

Power Tower

  • Fixes issue in power tower model and north field calculations.
  • Corrected units for DNI in hourly results.


  • Added the No Financials option for the Utility Scale Wind technology option.

Changes in version 2011.5.23 (since 2011.5.4)


  • Updated PV operation and maintenance default cost values
  • Update CEC PV module database to latest version
  • Updated Commercial PPA and Independent Power Producer financial models to handle sales tax and insurance in the same way as the new utility scale financial models
  • Revised the GetOutput function in SamUL to return on an error, instead of halting script execution
  • Additional cash flow line items for Sale-Leaseback financial structure
  • Receiver and tower cost equations updated in the Power Tower optimization module
  • Fixed calculation of system performance factor for combined systems (weighted by annual output)
  • Bug fix for temperature correction variable not being used correctly in the Generic Solar System model (CSP)
  • Utility scale wind users are now allowed to select a particular year of data to pull from server


Changes in version 2011.5.4


  • Improved default values for photovoltaic operation and maintenance costs
  • New Utility Scale Financing Options including All Equity Partnership Flip, Leveraged Partnership Flip, Sale-Leaseback, and Single Owner.
  • Improved usability and merged existing financial models into Residential, Commercial, Commercial PPA, and Independent Power Producer
  • Added backtracking algorithm for one axis tracking PV systems
  • Generic power model can accept hourly energy production input, calculated by an external model.
  • Added enhanced temperature correction algorithms for CEC PV module mounting options
  • Utility scale wind model with access to hourly wind datasets at various hub heights
  • Added Geothermal Co-Production model for coproducing geothermal power at the site of an oil or gas well
  • More detailed breakout of PV cost inputs
  • Numerous bug fixes and usability improvements throughout.


Changes in version SAM 2010.4.12


  • New solar water heating model for residential systems.
  • Tax credits and incentives can be defined as annual schedules.
  • Location lookup option automatically downloads NREL Solar Prospector weather data for U.S. locations using an address or latitude and longitude.
  • Simple load and storage models added to all photovoltaic models.
  • New physical model for parabolic trough systems.
  • Improved graphing capabilities and input pages.


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