Estimate panel temperature from ambient temperature and radiation

Additional parameter: temperature coefficient
Adapt efficiency according to these values
Bugfix input filter
Prepare V1.2

Author: woheller69

app/build.gradle

@@ -12,8 +12,8 @@ android {
         applicationId "org.woheller69.solxpect"
         minSdkVersion 26
         targetSdkVersion 31
-        versionCode 11
-        versionName "1.1"
+        versionCode 12
+        versionName "1.2"
 
         buildConfigField "String", "BASE_URL", "\"https://api.open-meteo.com/v1/\""
         buildConfigField "String", "GITHUB_URL","\"https://github.com/woheller69/solxpect/\""

app/src/main/assets/help/help-de.html

@@ -28,8 +28,11 @@ <h3>Zellen max. Leistung [W]</h3>
 <h3>Zelleneffizienz [%]</h3>
 Energieanteil in Form von Sonnenlicht, der von der Solarzelle in Strom umgewandelt werden kann.
 
+<h3>Temperaturkoeffizient  [%/K]</h3>
+Abhängigkeit der Leistung der Solarmodule von der Temperatur (normalerweise im Bereich von -0.4%/K).
+
 <h3>Zellenfläche [m<sup>2</sup>]</h3>
-Größe der aktiven Fläche Ihres Solarpanels.
+Fläche Ihres Solarpanels.
 
 <h3>Diffuse Strahlungseffizienz [%]</h3>
 Wirkungsgrad Ihres Solarkraftwerks bei diffuser Strahlung. Bei der Ausrichtung nach oben sollte er etwa 100 % betragen, bei der Ausrichtung zum Horizont etwa 50 %.

app/src/main/assets/help/help-en.html

@@ -28,8 +28,11 @@ <h3>Cells max power [W]</h3>
 <h3>Cells efficiency  [%]</h3>
 Portion of energy in the form of sunlight that can be converted into electricity by the solar cell.
 
+<h3>Temperature coefficient  [%/K]</h3>
+Dependence of the cell power on temperature (usually in the range of -0.4%/K).
+
 <h3>Cell area [m<sup>2</sup>]</h3>
-Size of the active area your solar panel.
+Size of your solar panel.
 
 <h3>Diffuse radiation efficiency  [%]</h3>
 Efficiency of your solar power plant for diffuse radiation. When pointing up it should be around 100%, when pointing to the horizon it may be around 50%.

app/src/main/java/org/woheller69/weather/SolarPowerPlant.java

@@ -14,6 +14,7 @@ public class SolarPowerPlant {
     double cellsMaxPower;
     double cellsArea;
     double cellsEfficiency;
+    double cellsTempCoeff;
     double diffuseEfficiency;
     double inverterPowerLimit;
     double inverterEfficiency;
@@ -22,7 +23,7 @@ public class SolarPowerPlant {
     private int[] shadingElevation;
     private int[] shadingOpacity;
 
-    public SolarPowerPlant(double latitude, double longitude, double cellsMaxPower, double cellsArea, double cellsEfficiency, double diffuseEfficiency, double inverterPowerLimit, double inverterEfficiency, double azimuthAngle, double tiltAngle, int[] shadingElevation, int[] shadingOpacity ) {
+    public SolarPowerPlant(double latitude, double longitude, double cellsMaxPower, double cellsArea, double cellsEfficiency, double cellsTempCoeff, double diffuseEfficiency, double inverterPowerLimit, double inverterEfficiency, double azimuthAngle, double tiltAngle, int[] shadingElevation, int[] shadingOpacity ) {
         this.latitude = latitude;
         this.longitude = longitude;
         this.cellsMaxPower = cellsMaxPower;
@@ -35,10 +36,11 @@ public SolarPowerPlant(double latitude, double longitude, double cellsMaxPower,
         this.tiltAngle = tiltAngle;
         this.shadingElevation = shadingElevation;
         this.shadingOpacity = shadingOpacity;
+        this.cellsTempCoeff = cellsTempCoeff / 100;
 
     }
 
-    public float getPower(double solarPowerNormal, double solarPowerDiffuse, long epochTimeSeconds) {
+    public float getPower(double solarPowerNormal, double solarPowerDiffuse, long epochTimeSeconds, float ambientTemperature) {
         Instant i = Instant.ofEpochSecond(epochTimeSeconds); //currentTimeMillis is in GMT
         ZonedDateTime dateTime = ZonedDateTime.ofInstant(i, ZoneId.of("GMT"));
 
@@ -70,10 +72,23 @@ public float getPower(double solarPowerNormal, double solarPowerDiffuse, long ep
                 }
             }
         }
-        double dcPower = (solarPowerNormal * efficiency + solarPowerDiffuse * diffuseEfficiency )* cellsEfficiency * cellsArea;
+
+        float totalRadiationOnCell = (float) (solarPowerNormal * efficiency + solarPowerDiffuse * diffuseEfficiency);  //flat plate equivalent of the solar irradiance
+        float cellTemperature = calcCellTemperature(ambientTemperature,totalRadiationOnCell);
+
+        double dcPower = totalRadiationOnCell * cellsEfficiency * (1+(cellTemperature - 25)*cellsTempCoeff) * cellsArea;
 
         double acPower = Math.min(dcPower * inverterEfficiency, inverterPowerLimit);
 
         return (float) acPower;
     }
+
+    public static float calcCellTemperature(float ambientTemperature, float totalIrradiance){
+        //models from here: https://www.scielo.br/j/babt/a/FBq5Pmm4gSFqsfh3V8MxfGN/  Photovoltaic Cell Temperature Estimation for a Grid-Connect Photovoltaic Systems in Curitiba
+        //float cellTemperature =  30.006f + 0.0175f*(totalIrradiance-300f)+1.14f*(ambientTemperature-25f);  //Lasnier and Ang  Lasnier, F.; Ang, T. G. Photovoltaic engineering handbook, 1st ed.; IOP Publishing LTD: Lasnier, France, 1990; pp. 258.
+        //float cellTemperature = ambientTemperature + 0.028f*totalIrradiance-1f;  //Schott Schott, T. Operation temperatures of PV modules. Photovoltaic solar energy conference 1985, pp. 392-396.
+        float cellTemperature = ambientTemperature + 0.0342f*totalIrradiance;  //Ross model: https://www.researchgate.net/publication/275438802_Thermal_effects_of_the_extended_holographic_regions_for_holographic_planar_concentrator
+        //assuming "not so well cooled" : 0.0342
+        return cellTemperature;
+    }
 }

app/src/main/java/org/woheller69/weather/activities/ManageLocationsActivity.java

@@ -187,6 +187,7 @@ private void editCityToWatch(CityToWatch city) {
         EditText editCellsMaxPower = (EditText) dialogView.findViewById(R.id.EditLocation_Cell_Max_Power);
         EditText editCellsArea = (EditText) dialogView.findViewById(R.id.EditLocation_Cells_Area);
         EditText editCellsEfficiency = (EditText) dialogView.findViewById(R.id.EditLocation_Cell_Efficiency);
+        EditText editCellsTempCoeff = (EditText) dialogView.findViewById(R.id.EditLocation_Cell_Temp_Coeff);
         EditText editDiffuseEfficiency = (EditText) dialogView.findViewById(R.id.EditLocation_Diffuse_Efficiency);
         EditText editInverterPowerLimit = (EditText) dialogView.findViewById(R.id.EditLocation_Inverter_Power_Limit);
         EditText editInverterEfficiency = (EditText) dialogView.findViewById(R.id.EditLocation_Inverter_Efficiency);
@@ -204,6 +205,8 @@ private void editCityToWatch(CityToWatch city) {
         editCellsArea.setText(Float.toString(city.getCellsArea()));
         editCellsEfficiency.setText(Float.toString(city.getCellsEfficiency()));
         editCellsEfficiency.setFilters(new InputFilter[]{ new InputFilterMinMax(0, 100)});
+        editCellsTempCoeff.setText(Float.toString(city.getCellsTempCoeff()));
+        editCellsTempCoeff.setFilters(new InputFilter[]{ new InputFilterMinMax(-100, 100)});
         editDiffuseEfficiency.setText(Float.toString(city.getDiffuseEfficiency()));
         editDiffuseEfficiency.setFilters(new InputFilter[]{ new InputFilterMinMax(0, 100)});
         editInverterPowerLimit.setText(Float.toString(city.getInverterPowerLimit()));
@@ -237,6 +240,7 @@ public void afterTextChanged(Editable editable) {
                     Float.parseFloat(editCellsMaxPower.getText().toString().isEmpty() ? "0" : editCellsMaxPower.getText().toString()),
                     Float.parseFloat(editCellsArea.getText().toString().isEmpty() ? "0" : editCellsArea.getText().toString()),
                     Float.parseFloat(editCellsEfficiency.getText().toString().isEmpty() ? "0" : editCellsEfficiency.getText().toString()),
+                    Float.parseFloat(editCellsTempCoeff.getText().toString().isEmpty() ? "0" : editCellsTempCoeff.getText().toString()),
                     Float.parseFloat(editDiffuseEfficiency.getText().toString().isEmpty() ? "0" : editDiffuseEfficiency.getText().toString()),
                     Float.parseFloat(editInverterPowerLimit.getText().toString().isEmpty() ? "0" : editInverterPowerLimit.getText().toString()),
                     Float.parseFloat(editInverterEfficiency.getText().toString().isEmpty() ? "0" : editInverterEfficiency.getText().toString()),

app/src/main/java/org/woheller69/weather/database/CityToWatch.java

@@ -17,6 +17,7 @@ public class CityToWatch {
     private float cellsMaxPower;
     private float cellsArea;
     private float cellsEfficiency;
+    private float cellsTempCoeff;
     private float diffuseEfficiency;
     private float inverterPowerLimit;
     private float inverterEfficiency;
@@ -36,14 +37,15 @@ public CityToWatch(int rank, int id, int cityId, float lon, float lat, String ci
         this.id = id;
         this.cityId = cityId;
         this.cityName = cityName;
-        this.cellsMaxPower=650;
-        this.cellsArea=3.18f;
-        this.cellsEfficiency=19.3f;
-        this.diffuseEfficiency=40;
-        this.inverterPowerLimit =600;
-        this.inverterEfficiency =95;
-        this.azimuthAngle=170;
-        this.tiltAngle =90;
+        this.cellsMaxPower = 650;
+        this.cellsArea = 3.18f;
+        this.cellsEfficiency = 19.3f;
+        this.cellsTempCoeff = -0.4f;
+        this.diffuseEfficiency = 40;
+        this.inverterPowerLimit = 600;
+        this.inverterEfficiency = 95;
+        this.azimuthAngle = 170;
+        this.tiltAngle = 90;
 
     }
 
@@ -182,4 +184,12 @@ public String getShadingElevationString() {
     public String getShadingOpacityString() {
         return Arrays.toString(shadingOpacity).replaceAll("\\[|\\]|\\s", "");
     }
+
+    public float getCellsTempCoeff() {
+        return cellsTempCoeff;
+    }
+
+    public void setCellsTempCoeff(float cellsTempCoeff) {
+        this.cellsTempCoeff = cellsTempCoeff;
+    }
 }

app/src/main/java/org/woheller69/weather/database/SQLiteHelper.java

@@ -20,7 +20,7 @@
  */
 public class SQLiteHelper extends SQLiteOpenHelper {
 
-    private static final int DATABASE_VERSION = 1;
+    private static final int DATABASE_VERSION = 2;
     private Context context;
 
     private List<City> allCities = new ArrayList<>();
@@ -53,6 +53,7 @@ public class SQLiteHelper extends SQLiteOpenHelper {
     private static final String CITIES_TO_WATCH_TILT_ANGLE = "tilt_angle";
     private static final String CITIES_TO_WATCH_SHADING_ELEVATION = "shading_elevation";
     private static final String CITIES_TO_WATCH_SHADING_OPACITY = "shading_opacity";
+    private static final String CITIES_TO_WATCH_CELLS_TEMP_COEFF = "cells_temp_coeff";
 
     //Names of columns in TABLE_FORECAST
     private static final String FORECAST_ID = "forecast_id";
@@ -135,7 +136,8 @@ public class SQLiteHelper extends SQLiteOpenHelper {
             CITIES_TO_WATCH_AZIMUTH_ANGLE + " REAL NOT NULL," +
             CITIES_TO_WATCH_TILT_ANGLE + " REAL NOT NULL," +
             CITIES_TO_WATCH_SHADING_ELEVATION + " VARCHAR(255) NOT NULL," +
-            CITIES_TO_WATCH_SHADING_OPACITY + " VARCHAR(255) NOT NULL)";
+            CITIES_TO_WATCH_SHADING_OPACITY + " VARCHAR(255) NOT NULL," +
+            CITIES_TO_WATCH_CELLS_TEMP_COEFF + " REAL NOT NULL)";
 
     public static SQLiteHelper getInstance(Context context) {
         if (instance == null && context != null) {
@@ -160,6 +162,12 @@ public void onCreate(SQLiteDatabase db) {
 
     @Override
     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+        switch(oldVersion) {
+            case 1:
+                db.execSQL("ALTER TABLE "+TABLE_CITIES_TO_WATCH+" ADD COLUMN "+CITIES_TO_WATCH_CELLS_TEMP_COEFF+" REAL DEFAULT 0");
+                // we want both updates, so no break statement here...
+        }
+
     }
 
 
@@ -185,6 +193,7 @@ public synchronized long addCityToWatch(CityToWatch city) {
         values.put(CITIES_TO_WATCH_TILT_ANGLE,city.getTiltAngle());
         values.put(CITIES_TO_WATCH_SHADING_ELEVATION,city.getShadingElevationString());
         values.put(CITIES_TO_WATCH_SHADING_OPACITY,city.getShadingOpacityString());
+        values.put(CITIES_TO_WATCH_CELLS_TEMP_COEFF,city.getCellsTempCoeff());
 
         long id=database.insert(TABLE_CITIES_TO_WATCH, null, values);
 
@@ -218,6 +227,7 @@ public synchronized CityToWatch getCityToWatch(int id) {
                         ", " + CITIES_TO_WATCH_TILT_ANGLE +
                         ", " + CITIES_TO_WATCH_SHADING_ELEVATION +
                         ", " + CITIES_TO_WATCH_SHADING_OPACITY +
+                        ", " + CITIES_TO_WATCH_CELLS_TEMP_COEFF +
                         ", " + CITIES_TO_WATCH_COLUMN_RANK +
                         " FROM " + TABLE_CITIES_TO_WATCH +
                         " WHERE " + CITIES_TO_WATCH_CITY_ID + " = ?", arguments);
@@ -240,7 +250,8 @@ public synchronized CityToWatch getCityToWatch(int id) {
             cityToWatch.setTiltAngle(Float.parseFloat(cursor.getString(12)));
             cityToWatch.setShadingElevation(cursor.getString(13));
             cityToWatch.setShadingOpacity(cursor.getString(14));
-            cityToWatch.setRank(Integer.parseInt(cursor.getString(15)));
+            cityToWatch.setCellsTempCoeff(Float.parseFloat(cursor.getString(15)));
+            cityToWatch.setRank(Integer.parseInt(cursor.getString(16)));
 
             cursor.close();
         }
@@ -271,6 +282,7 @@ public synchronized List<CityToWatch> getAllCitiesToWatch() {
                         ", " + CITIES_TO_WATCH_TILT_ANGLE +
                         ", " + CITIES_TO_WATCH_SHADING_ELEVATION +
                         ", " + CITIES_TO_WATCH_SHADING_OPACITY +
+                        ", " + CITIES_TO_WATCH_CELLS_TEMP_COEFF +
                         ", " + CITIES_TO_WATCH_COLUMN_RANK +
                         " FROM " + TABLE_CITIES_TO_WATCH
                 , new String[]{});
@@ -295,7 +307,8 @@ public synchronized List<CityToWatch> getAllCitiesToWatch() {
                 cityToWatch.setTiltAngle(Float.parseFloat(cursor.getString(12)));
                 cityToWatch.setShadingElevation(cursor.getString(13));
                 cityToWatch.setShadingOpacity(cursor.getString(14));
-                cityToWatch.setRank(Integer.parseInt(cursor.getString(15)));
+                cityToWatch.setCellsTempCoeff(Float.parseFloat(cursor.getString(15)));
+                cityToWatch.setRank(Integer.parseInt(cursor.getString(16)));
 
                 cityToWatchList.add(cityToWatch);
             } while (cursor.moveToNext());
@@ -325,6 +338,7 @@ public synchronized void updateCityToWatch(CityToWatch cityToWatch) {
         values.put(CITIES_TO_WATCH_TILT_ANGLE,cityToWatch.getTiltAngle());
         values.put(CITIES_TO_WATCH_SHADING_ELEVATION,cityToWatch.getShadingElevationString());
         values.put(CITIES_TO_WATCH_SHADING_OPACITY,cityToWatch.getShadingOpacityString());
+        values.put(CITIES_TO_WATCH_CELLS_TEMP_COEFF,cityToWatch.getCellsTempCoeff());
 
         database.update(TABLE_CITIES_TO_WATCH, values, CITIES_TO_WATCH_ID + " = ?",
                 new String[]{String.valueOf(cityToWatch.getId())});

app/src/main/java/org/woheller69/weather/ui/Help/InputFilterMinMax.java

@@ -5,27 +5,40 @@
 
 public class InputFilterMinMax implements InputFilter {
 
-    private int min, max;
+    private float min, max;
 
-    public InputFilterMinMax(int min, int max) {
+    public InputFilterMinMax(float min, float max) {
         this.min = min;
         this.max = max;
     }
 
 
     @Override
     public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
-        String oldString = dest.toString();
-        String insertString = source.toString();
-        String newString = new StringBuilder(oldString).insert(dstart,insertString).toString();
-        float input = Float.parseFloat(newString);
-        if (isInRange(min, max, input))
-            return null;
-        else
-            return "";
+        try {
+            String oldString = dest.toString();
+            String insertString = source.toString();
+            String newString = oldString.substring(0, dstart) + oldString.substring(dend);
+            newString = newString.substring(0, dstart) + insertString + newString.substring(dstart);
+            float input = Float.parseFloat(newString);
+
+            if (isInRange(min, max, input)) {
+                return null;
+            } else {
+                if (source.equals("") && dest.toString().length() != 1) {
+                    //backspace was clicked, do not accept that change, unless user is deleting the last char
+                    return dest.subSequence(dstart, dend);
+                } else {
+                    return "";
+                }
+            }
+        } catch (NumberFormatException e) {
+            e.printStackTrace();
+        }
+        return "";
     }
 
-    private boolean isInRange(int a, int b, float c) {
+    private boolean isInRange(float a, float b, float c) {
         return b > a ? c >= a && c <= b : c >= b && c <= a;
     }
 

app/src/main/java/org/woheller69/weather/ui/RecycleList/ItemViewHolder.java

@@ -23,6 +23,7 @@ public class ItemViewHolder extends RecyclerView.ViewHolder {
     public TextView cellsMaxPower;
     public TextView cellsArea;
     public TextView cellsEfficiency;
+    public TextView cellsTempCoeff;
     public TextView diffuseEfficiency;
     public TextView inverterPowerLimit;
     public TextView inverterEfficiency;
@@ -41,6 +42,7 @@ public ItemViewHolder(View itemView) {
         this.cellsMaxPower = (TextView) itemView.findViewById(R.id.city_cells_max_power);
         this.cellsArea = (TextView) itemView.findViewById(R.id.city_cells_area);
         this.cellsEfficiency = (TextView) itemView.findViewById(R.id.city_cells_efficiency);
+        this.cellsTempCoeff = (TextView) itemView.findViewById(R.id.city_cells_temp_coeff);
         this.diffuseEfficiency = (TextView) itemView.findViewById(R.id.city_diffuse_efficiency);
         this.inverterPowerLimit = (TextView) itemView.findViewById(R.id.city_inverter_power_limit);
         this.inverterEfficiency = (TextView) itemView.findViewById(R.id.city_inverter_efficiency);

app/src/main/java/org/woheller69/weather/ui/RecycleList/RecyclerOverviewListAdapter.java

@@ -63,6 +63,7 @@ public void onBindViewHolder(ItemViewHolder holder, int position) {
         holder.tiltAngle.setText(context.getString(R.string.edit_location_hint_tilt) +": "+ cities.get(position).getTiltAngle());
         holder.cellsMaxPower.setText(context.getString(R.string.edit_location_hint_cells_max_power) +": "+ cities.get(position).getCellsMaxPower());
         holder.cellsEfficiency.setText(context.getString(R.string.edit_location_hint_cells_efficiency) +": "+ cities.get(position).getCellsEfficiency());
+        holder.cellsTempCoeff.setText(context.getString(R.string.edit_location_hint_cells_temp_coeff) +": "+ cities.get(position).getCellsTempCoeff());
         holder.cellsArea.setText(context.getString(R.string.edit_location_hint_cells_area) +": "+ cities.get(position).getCellsArea());
         holder.diffuseEfficiency.setText(context.getString(R.string.edit_location_hint_diffuse_efficiency) +": "+ cities.get(position).getDiffuseEfficiency());
         holder.inverterPowerLimit.setText(context.getString(R.string.edit_location_hint_inverter_power_limit) +": "+ cities.get(position).getInverterPowerLimit());
@@ -114,7 +115,7 @@ public void onItemMove(int fromPosition, int toPosition) {
     public CityToWatch getCitytoWatch(int position){
         return cities.get(position);
     }
-    public void updateCity(CityToWatch cityToWatch, String cityName, float latitude, float longitude, float azimuth, float tilt, float cellsMaxPower, float cellsArea, float cellsEfficiency, float diffuseEfficiency, float inverterPowerLimit, float inverterEfficiency, int[] shadingElevation, int[] shadingOpacity) {
+    public void updateCity(CityToWatch cityToWatch, String cityName, float latitude, float longitude, float azimuth, float tilt, float cellsMaxPower, float cellsArea, float cellsEfficiency, float cellsTempCoeff, float diffuseEfficiency, float inverterPowerLimit, float inverterEfficiency, int[] shadingElevation, int[] shadingOpacity) {
         cityToWatch.setCityName(cityName);
         cityToWatch.setLatitude(latitude);
         cityToWatch.setLongitude(longitude);
@@ -123,6 +124,7 @@ public void updateCity(CityToWatch cityToWatch, String cityName, float latitude,
         cityToWatch.setCellsMaxPower(cellsMaxPower);
         cityToWatch.setCellsArea(cellsArea);
         cityToWatch.setCellsEfficiency(cellsEfficiency);
+        cityToWatch.setCellsTempCoeff(cellsTempCoeff);
         cityToWatch.setDiffuseEfficiency(diffuseEfficiency);
         cityToWatch.setInverterPowerLimit(inverterPowerLimit);
         cityToWatch.setInverterEfficiency(inverterEfficiency);