The Solar Advisor Model Version SAM 2009 provides a consistent framework for analyzing and comparing power system costs and performance across the range of solar technologies and markets, from photovoltaic systems for residential and commercial markets to concentrating solar power and large photovoltaic systems for utility markets.
The Solar Advisor Model can be downloaded for free from the Solar Advisor website https://www.nrel.gov/analysis/sam/.
Solar Advisor is based on an hourly simulation engine that interacts with performance, cost, and finance models to calculate energy output, energy costs, and cash flows. The software can also account for the effect of incentives on project cash flows. Solar Advisor's spreadsheet interface allows for exchanging data with external models developed in Microsoft® Excel. The model provides options for parametric studies, sensitivity analysis, optimization, and statistical analyses to investigate impacts of variations and uncertainty in performance, cost, and financial parameters on model results.
Solar Advisor models system performance using the TRNSYS software developed at the University of Wisconsin combined with customized components. TRNSYS is a validated, time-series simulation program that can simulate the performance of photovoltaic, concentrating solar power, water heating systems, and other renewable energy systems using hourly resource data. TRNSYS is integrated into Solar Advisor so there is no need to install TRNSYS software or be familiar with its use to run Solar Advisor.
The Department of Energy's Solar Energy Technologies Program (SETP) initially developed Solar Advisor for analysis to support the implementation of the SETP Systems Driven Approach. The model also has applications for the solar industry for planning research and development programs, and developing project cost and performance estimates. Solar Advisor is being used as part of the solicitation and evaluation process for SETP funding programs.
The current version of the Solar Advisor Model models photovoltaic and concentrating solar power technologies for electric applications in several markets. Solar Advisor also includes a simple model of fuel-based electric generation that can be used to model baseline systems for comparison with the solar technologies. The current version of the Solar Advisor Model does not model solar heating and lighting technologies.
Photovoltaic Systems
Photovoltaic systems in Solar Advisor can be based on flat-plate system or concentrating photovoltaic modules. Solar Advisor offers several options for modeling flat-plate modules, and one option for concentrating photovoltaic modules.
Table 1. Current status of photovoltaic modeling
Technology
|
Module
|
Inverter
|
Storage and Loads
|
Flat-plate photovoltaic
|
| • | Sandia PV Array Performance Model |
|
| • | Sandia Performance Model for Grid-Connected PV Inverters |
|
| • | A prototype model is available for testing with the PVWatts Solar Array model. |
|
Concentrating photovoltaic
|
|
| • | Sandia Performance Model for Grid-Connected PV Inverters |
|
|
The efficiency models are simplified representations of either modules or inverters based on rated capacities in Watts or kilowatts and efficiency values. The flat-plate PV simple efficiency model also includes a simple representation of module temperature effects. The Sandia and CEC models include parameter libraries for commercially available PV modules and inverters maintained by Sandia National Laboratories and the California Energy Commission (CEC), respectively. Modules and inverters only recently introduced to the market may not be available in the parameter libraries.
Concentrating Solar Power Systems
Solar Advisor models parabolic trough, power tower, and dish-Stirling concentrating solar power systems. The trough model is based on NREL's Excelergy model. The dish-Stirling and power tower models are based on research at the University of Wisconsin.
Table 2. Current status of Concentrating Solar Power modeling
Technology
|
Solar Field
|
Collector and Receiver
|
Power
Block
|
Storage
|
Parasitics
|
Parabolic trough
|
| • | Layout as multiple of design point or specified area |
| • | List of heat transfer fluid options |
|
| • | Library of collector types |
| • | Library of receiver types and condition |
|
| • | Library of power cycle types |
|
| • | Storage capacity defined in number of hours at full load |
|
| • | Library of parameter sets for parasitic losses |
|
Dish-stirling
|
| • | Field area defined by number of collectors and separation |
|
| • | Mirror area reflectivity parameters |
| • | Conduction, convection, and radiation parameters |
|
| • | Stirling engine part-to-full load efficiency curve |
| • | Engine operating parameters |
|
|
| • | Pump and fan motor loss parameters |
|
Power tower
|
| • | Heliostat positions defined either in radial zones or individual x-y coordinates |
| • | Solar field optimization wizard |
|
| • | Molten-salt external Receiver |
| • | Eight options for heat transfer fluid flow through the receiver |
|
| • | Polynomial regression model using design electric output, cycle efficiency, inlet and outlet temperatures, and mass flow rate |
|
| • | Storage capacity defined in number of hours at full load |
|
| • | Library of parameter sets for parasitic losses |
|
Generic (Fuel-based) Systems
The generic model is a simple, linear, efficiency-based representation of the performance of a fuel-based electricity generator coupled to Solar Advisor's cost model.
Table 3. Current status of Generic fuel-based electric generation modeling
Technology
|
Configuration
|
Generic
|
First year annual output calculated as a function of nameplate capacity, heat rate, capacity factor and other performance factors.
|
Financial and Incentive Models
Solar Advisor calculates economic metrics including the levelized cost of energy for a project based on the system's annual electric output and annual cash flow that captures installation and operating costs, taxes, incentives, and the cost of debt. The model includes a set of sample templates that contain default cost values that can be used as a starting point for analyses. The default cost values are representative of average U.S. costs at the time of the model's release, but of course do not capture the actual costs for any specific project. For more information about the financing options available in Solar Advisor, see Technology and Market.
