Merge pull request #1128 from NREL/snow-slide-coeff

Expose snow slide coefficient in ssc
NREL · Feb 29, 2024 · 936dd95 · 936dd95
2 parents 5599c03 + 58e2bcc
commit 936dd95
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Showing 7 changed files with 14 additions and 10 deletions.
diff --git a/shared/lib_pv_io_manager.cpp b/shared/lib_pv_io_manager.cpp
@@ -505,7 +505,7 @@ Subarray_IO::Subarray_IO(compute_module* cm, const std::string& cmName, size_t s
             if (trackMode == irrad::SEASONAL_TILT)
                 throw exec_error(cmName, "Time-series tilt input may not be used with the snow model at this time: subarray " + util::to_string((int)(subarrayNumber)));
             // if tracking mode is 1-axis tracking, don't need to limit tilt angles
-            if (snowModel.setup(selfShadingInputs.nmody, (float)tiltDegrees, (trackMode != irrad::SINGLE_AXIS))) {
+            if (snowModel.setup(selfShadingInputs.nmody, (float)tiltDegrees, cm->as_double("snow_slide_coefficient"), (trackMode != irrad::SINGLE_AXIS))) {
                 if (!snowModel.good) {
                     cm->log(snowModel.msg, SSC_ERROR);
                 }

diff --git a/shared/lib_snowmodel.cpp b/shared/lib_snowmodel.cpp
@@ -62,7 +62,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 pvsnowmodel::pvsnowmodel()
 {
 	mSlope = -80;
-	sSlope = (float)1.97;
+	//sSlope = (float)1.97;
 	deltaThreshold = 1.00;
 	depthThreshold = 1.00;
 	previousDepth = 0;
@@ -76,11 +76,11 @@ pvsnowmodel::pvsnowmodel()
 
 }
 
-bool pvsnowmodel::setup(int nmody_in, float baseTilt_in, bool limitTilt){
+bool pvsnowmodel::setup(int nmody_in, float baseTilt_in, float snow_slide_coeff, bool limitTilt){
 
 	nmody = nmody_in;
 	baseTilt = baseTilt_in;
-
+    sSlope = snow_slide_coeff;
 	if(limitTilt && (baseTilt>45 || baseTilt < 10)){
 		good = true;
 		msg = util::format("The snow model is designed to work for PV arrays with a tilt angle between 10 and 45 degrees, but will generate results for tilt angles outside this range. The system you are modeling includes a subarray tilt angle of %f degrees.", baseTilt);

diff --git a/shared/lib_snowmodel.h b/shared/lib_snowmodel.h
@@ -41,7 +41,7 @@ class pvsnowmodel
 	pvsnowmodel();
 
 	// limitTilt requires tilt to be between 10 and 45 degrees
-	bool setup(int, float, bool limitTilt = true);
+	bool setup(int, float, float snow_slide_coeff = 1.97, bool limitTilt = true);
 
 	bool getLoss(float poa, float tilt, float wspd, float tdry, float snowDepth, int sunup, float dt, float &returnLoss);
 
@@ -63,4 +63,4 @@ class pvsnowmodel
 							//  if an error has occured
 };
 
-#endif
+#endif
diff --git a/ssc/cmod_pvsamv1.cpp b/ssc/cmod_pvsamv1.cpp
@@ -63,6 +63,8 @@ static var_info _cm_vtab_pvsamv1[] = {
 
         // misc inputs
         {SSC_INPUT, SSC_NUMBER,   "en_snow_model",                        "Toggle snow loss estimation",                         "0/1",    "",                                                                                                                                                                                      "Losses",                                                "?=0",                                "BOOLEAN",             "" },
+        { SSC_INPUT,        SSC_NUMBER,     "snow_slide_coefficient",		"Snow Slide Coefficient",			"",					"",					"Losses", "?=1.97",           "",                             "" },
+
         {SSC_INPUT, SSC_NUMBER,   "system_capacity",                      "DC Nameplate capacity",                               "kWdc",   "",                                                                                                                                                                                      "System Design",                                         "*",                                  "",                    "" },
         {SSC_INPUT, SSC_NUMBER,   "use_wf_albedo",                        "Use albedo in weather file if provided",              "0/1",    "0=user-specified,1=weatherfile",                                                                                                                                                        "Solar Resource",                                        "?=1",                                "BOOLEAN",             "" },
         {SSC_INPUT, SSC_NUMBER,   "use_spatial_albedos",                  "Use spatial albedo values",                           "0/1",    "0=no,1=yes",                                                                                                                                                                            "Solar Resource",                                        "?=0",                                "BOOLEAN",             "" },

diff --git a/ssc/cmod_pvwattsv7.cpp b/ssc/cmod_pvwattsv7.cpp
@@ -600,7 +600,7 @@ class cm_pvwattsv7 : public compute_module
             // if tracking mode is 1-axis tracking,
             // don't need to limit tilt angles
             if (snowmodel.setup(pv.nmody,
-                (float)pv.tilt,
+                (float)pv.tilt, 1.97, 
                 pv.type == FIXED_RACK || pv.type == FIXED_ROOF)) {
 
                 if (!snowmodel.good) {

diff --git a/ssc/cmod_pvwattsv8.cpp b/ssc/cmod_pvwattsv8.cpp
@@ -657,7 +657,7 @@ class cm_pvwattsv8 : public compute_module
             // if tracking mode is 1-axis tracking,
             // don't need to limit tilt angles
             if (snowmodel.setup(pv.nmody,
-                (float)pv.tilt,
+                (float)pv.tilt, 1.97,
                 pv.type == FIXED_RACK || pv.type == FIXED_ROOF)) {
 
                 if (!snowmodel.good) {

diff --git a/ssc/cmod_snowmodel.cpp b/ssc/cmod_snowmodel.cpp
@@ -70,7 +70,8 @@ static var_info _cm_vtab_snowmodel[] =
 	{ SSC_INPUT,        SSC_NUMBER,     "subarray1_nmody",			"Number of Modules in a Row","",				"",					"PV Snow Model", "*",           "",                             "" },
 	{ SSC_INPUT,        SSC_NUMBER,     "subarray1_tilt",			"Base tilt",				"Degrees",			"",					"PV Snow Model", "*",           "",                             "" },
 	{ SSC_INPUT,        SSC_NUMBER,     "subarray1_track_mode",		"Tracking Mode",			"",					"",					"PV Snow Model", "*",           "",                             "" },
-
+    { SSC_INPUT,        SSC_NUMBER,     "snow_slide_coefficient",		"Snow Slide Coefficient",			"",					"",					"PV Snow Model", "?=1.97",           "",                             "" },
+
 	{ SSC_OUTPUT,       SSC_ARRAY,      "hourly_energy_before_snow","Hourly Energy Without Snow Loss","kwh",		"",                 "Time Series",		"*",           "",			"" },
 	{ SSC_OUTPUT,       SSC_ARRAY,      "monthly_energy_before_snow","Monthly Energy Without Snow Loss","kwh",		"",                 "Monthly",			"*",           "",			"" },
 	{ SSC_OUTPUT,       SSC_NUMBER,     "annual_energy_before_snow","Annual Energy Without Snow Losses","kwh",		"",                 "Annual",			"*",           "",								"" },
@@ -111,7 +112,8 @@ class cm_snowmodel : public compute_module
 		int nmody = as_integer("subarray1_nmody");								// The number of modules in a row
 		int baseTilt = as_integer("subarray1_tilt");							// The tilt for static systems
 		//int trackMode = as_integer("subarray1_track_mode");						// The systems tracking mode (0 -> static, 1 -> 1 axis tracking)
-
+        double snow_slide_coeff = 1.97;
+        if (is_assigned("snow_slide_coefficient")) snow_slide_coeff = as_double("snow_slide_coefficient");
 		// Define output arrays and variables
 		ssc_number_t *hrEn_b4Snow = allocate( "hourly_energy_before_snow", num_steps);	// Hourly Energy with Snow Modeld