# pvl_sapmmoduledb

Retrieves a set of SAPM coefficients from an Excel spreadsheet.

## Contents

- Syntax
- Description
- Inputs
- Outputs
- Example
- References
- See Also

## Syntax

`SAPMparam = pvl_sapmmoduledb(Entry)`

`SAPMparam = pvl_sapmmoduledb(Entry, DBfile)`

## Description

Retrieves a set of Sandia Array Performance Model (SAPM) coefficients from an Excel spreadsheet. The workbook must be in the same format as the "SandiaModuleDatabase_20111114.xlsx" example file included with the PVLib toolbox. A description of each of the coefficients associated with SAPM is given in the Output section of this help document, along with the column numbers of the data within the Excel sheet.

## Inputs

- `Entry` - The entry number of the desired module. Entry is the numeric order of the PV modules in the spreadsheet, not including header rows. For example, if there is a single row of text-based header information in the spreadsheet, and the user desires the module in row number 35, then Entry = 34 = (35 - 1) where the "-1" accounts for the single text-based header row.
- `DBfile` - an optional argument which allows the user to select which "database" file should be read. A file path may also be necessary if the desired file is not in the MATLAB working path. If the input DBfile is not included, the user will be prompted to select a file using a browsing window. The file should be an Excel workbook with the module data in a sheet called "Data". Row 1 should be text headers. Rows 2-n contain the data specified below in columns 1 through 42 (A through AQ).

## Outputs

- `SAPMparam` - A struct of SAPM module performance parameters [1]. Note that the reference condition specified for most modules is Ee = 1, cell temperature = 25C, AMa = 1.5.

- `SAPMparam.name` = Module model name and manufacturer. Given in column 1
- `SAPMparam.vintage` = Module vintage, approximate year of manufacture or test. '(E)' denotes modules which have estimated parameters from testing of a similar module. Given in Column 2.
- `SAPMparam.material` = PV semiconductor material text found in column 4.
- `SAPMparam.area` = Area of module in m^2 measured to outside of frame. Numeric found in column 3.
- `SAPMparam.AlphaIsc` = Temperature coefficient of Isc in units of (1/C) at reference temperature (usually 25C). Numeric found in column 11.
- `SAPMparam.AlphaImp` = Temperature coefficient of Imp in units of (1/C) at reference temperature (usually 25C). Numeric found in column 12.
- `SAPMparam.Isc0` = Short circuit current at reference condition in units of amperes. Numeric found in column 7.
- `SAPMparam.Imp0` = Maximum power current at reference condition in units of amperes. Numeric found in column 9.
- `SAPMparam.Voc0` = Open circuit voltage at reference condition in units of volts. Numeric found in column 8.
- `SAPMparam.Vmp0` = Maximum power voltage at reference condition in units of volts. Numeric found in column 10.
- `SAPMparam.BetaVoc` = Open circuit voltage temperature coefficient at reference condition (V/C). Numeric found in column 15.
- `SAPMparam.BetaVmp` = Maximum power voltage temperature coefficient at reference condition (V/C). Numeric found in column 17.
- `SAPMparam.mBetaVoc` = Coefficient providing the irradiance dependence for the BetaVoc temperature coefficient at reference irradiance (V/C). Numeric found in column 16.
- `SAPMparam.mBetaVmp` = Coefficient providing the irradiance dependence for the BetaVmp temperature coefficient at reference irradiance (V/C). Numeric found in column 17.
- `SAPMparam.Ns` = Number of cells in series in a module's cell string(s), numeric found in column 5
- `SAPMparam.Np` = Number of parallel cell strings in the module, numeric found in column 6
- `SAPMparam.delT` = Temperature difference, in C, between module's backside and the cells at reference irradiance. Typically more associated with the array mounting configuration than the module's construction properties. Numeric found in column 33.
- `SAPMparam.fd` = Fraction of diffuse irradiance used by the module (unitless). Typically assumed to be 1 for flat-plate modules. For point-focus concentrator modules, a value of 0 is assumed, and for low-concentration modules a value between 0 and 1 can be determined. Numeric found in column 34.
- `SAPMparam.n` = Empirically determined "diode factor" (dimensionless). Numeric found in column 19.
- `SAPMparam.Ix0` = Current, in amperes, of the point at 0.5*Voc at reference conditions. Numeric found in column 39.
- `SAPMparam.Ixx0` = Current, in amperes, of the point at 0.5*(Voc+Vmp) at reference conditions. Numeric found in column 40.
- `SAPMparam.a_wind` = parameter for establishing the upper limit for module temperature at low wind speeds and high solar irradiance (unitless). This coefficient is strongly influenced by the array mounting configuration, and should be adjusted accordingly. Numeric found in column 35.
- `SAPMparam.b_wind` = parameter for establishing the rate at which the module temperature drops as wind speed increases (unitless). This coefficient is strongly influenced by the array mounting configuration, and should be adjusted accordingly. Numeric found in column 36.

- `SAPMparam.c` = a 1x8 vector of C values described in [1].

- `SAPMparam.c(1)` = C0, in column 13, value relating Imp to Ee (unitless).
- `SAPMparam.c(2)` = C1, in column 14, value relating Imp to Ee (unitless).
- `SAPMparam.c(3)` = C2, in column 20, value relating Vmp to Ee (unitless).
- `SAPMparam.c(4)` = C3, in column 21, value relating Vmp to Ee (1/V).
- `SAPMparam.c(5)` = C4, in column 37, value relating Ix to Ee (unitless).
- `SAPMparam.c(6)` = C5, in column 38, value relating Ix to Ee (unitless).
- `SAPMparam.c(7)` = C6, in column 41, value relating Ixx to Ee (unitless).
- `SAPMparam.c(8)` = C7, in column 42, value relating Ixx to Ee (unitless).

- `SAPMparam.a` = a 1x5 vector of polynomial coefficients relating module current response to absolute (pressure-corrected) airmass.
- `SAPMparam.a(5)` = A0, in column 22, constant coefficient of f1(AMa).
- `SAPMparam.a(4)` = A1, in column 23, 1st order coefficient of f1(AMa).
- `SAPMparam.a(3)` = A2, in column 24, 2nd order coefficient of f1(AMa).
- `SAPMparam.a(2)` = A3, in column 25, 3rd order coefficient of f1(AMa).
- `SAPMparam.a(1)` = A4, in column 26, 4th order coefficient of f1(AMa).

- `SAPMparam.b` = a 1x6 vector of polynomial coefficients relating module current response to incident angle (AOI).

- `SAPMparam.b(6)` = B0, in column 27, constant coefficient of f2(AOI).
- `SAPMparam.b(5)` = B1, in column 28, 1st order coefficient of f2(AOI).
- `SAPMparam.b(4)` = B2, in column 29, 2nd order coefficient of f2(AOI).
- `SAPMparam.b(3)` = B3, in column 30, 3rd order coefficient of f2(AOI).
- `SAPMparam.b(2)` = B4, in column 31, 4th order coefficient of f2(AOI).
- `SAPMparam.b(1)` = B5, in column 32, 5th order coefficient of f2(AOI).

## Example

    DBfile = 'SandiaModuleDatabase_20120925.xlsx';
    SAPMparam = pvl_sapmmoduledb(123, DBfile)

    SAPMparam =

            name: 'Canadian Solar CS5P-220M'
         vintage: 2009
        material: 'c-Si'
            area: 1.7010
        AlphaIsc: 3.9700e-04
        AlphaImp: 1.8100e-04
            Isc0: 5.0911
            Imp0: 4.5463
            Voc0: 59.2608
            Vmp0: 48.3156
         BetaVoc: -0.2170
         BetaVmp: -0.2355
        mBetaVoc: 0
        mBetaVmp: 0
              Ns: 96
              Np: 1
            delT: 3
              fd: 1
               n: 1.4032
             Ix0: 4.9760
            Ixx0: 3.1880
          a_wind: -3.4064
          b_wind: -0.0842
               c: [1.0128 -0.0128 0.2793 -7.2446 0.9964 0.0036 1.1554 -0.1554]
               a: [-6.9304e-05 0.0017 -0.0158 0.0681 0.9284]
               b: [-1.3590e-09 2.1120e-07 -1.2460e-05 3.1030e-04 -0.0024 1]

## References

[1] King, D. et al, 2004. Sandia Photovoltaic Array Performance Model, SAND2004-3535, Sandia National Laboratories, Albuquerque, NM. Web Link

## See Also

`pvl_sapm`, `pvl_sapmcelltemp`

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