Merge branch 'JrtPec-solar-irradiance' into develop

Author: saroele

opengrid/library/solarmodel.py

@@ -0,0 +1,253 @@
+__author__ = 'Jan Pecinovsky'
+
+import geocoder
+import astral
+import math
+import pandas as pd
+
+class SolarInsolation(object):
+    """
+        Module to calculate Solar Insolation (direct intensity, global intensity, air mass) and
+        basic solar parameters (angle) based on a location and a date.
+        Formulas from pveducation.org
+    """
+    def __init__(self, location):
+        """
+            Parameters
+            ----------
+            location: String
+        """
+        self.location = geocoder.google(location)
+        self.elevation = geocoder.google(self.location.latlng, method='Elevation').elevation
+        self.astral = astral.Astral()
+
+    def _airMass(self, angleFromVertical):
+        """
+            Raw formula to calculate air mass
+
+            Parameters
+            ----------
+            angleFromVertical: float
+                in radians
+
+            Returns
+            -------
+            float
+        """
+        denom = math.cos(angleFromVertical) + 0.50572 * (96.07995 - angleFromVertical) ** -1.6364
+        if denom >= 0:
+            return 1 / denom
+        else:
+            return -1
+
+    def airMass(self, datetime):
+        """
+            Calculate air mass for a given date and time
+
+            Parameters
+            ----------
+            datetime: datetime.datetime
+
+            Returns
+            -------
+            float
+        """
+        angleFromVertical = (math.pi/2) - self.solarElevation(datetime)
+        return self._airMass(angleFromVertical)
+
+    def _directIntensity(self, elevation, airMass):
+        """
+            Raw Formula to calculate direct solar beam intensity
+
+            Parameters
+            ---------
+            elevation: float
+                in meters
+            airMass: float
+
+            Returns
+            -------
+            float
+                in W/m**2
+        """
+        elevation = elevation / 1000 #formula uses km
+        di = 1.353 * ((1 - 0.14*elevation) * 0.7**airMass**0.678 + 0.14*elevation)
+        return di*1000 #formula output is kW/m**2
+
+    def directIntensity(self, datetime):
+        """
+            Calculate direct solar beam intensity for a given date and time
+
+            Parameters
+            ----------
+            datetime: datetime.datetime
+
+            Returns
+            -------
+            float
+                in W/m**2
+        """
+        airMass = self.airMass(datetime)
+        if airMass == -1:
+            return 0
+        return self._directIntensity(self.elevation, airMass)
+
+    def _backgroundIrradiance(self, directIntensity):
+        """
+        Calculate the background irradiance, which is 10% of the direct intensity
+        :param directIntensity: float
+        :return: float
+        """
+
+        return 0.1 * directIntensity
+
+    def _globalIrradiance(self, directIntensity):
+        """
+            Raw formula to calculate global solar irradiance
+
+            Parameters
+            ----------
+            directIntensity: float
+                in W/m**2
+
+            Returns
+            -------
+            float
+                in W/m**2
+        """
+        return directIntensity + self._backgroundIrradiance(directIntensity)
+
+    def globalIrradiance(self, datetime):
+        """
+            Calculate global solar irradiance for a given date and time
+
+            Parameters
+            ----------
+            datetime: datetime.datetime
+
+            Returns
+            -------
+            float
+                in W/m**2
+        """
+        directIntensity = self.directIntensity(datetime)
+        return self._globalIrradiance(directIntensity)
+
+    def solarElevation(self, datetime):
+        """
+            Calculate angle of the sun above the horizon
+
+            Parameters
+            ----------
+            datetime: datetime.datetime
+
+            Returns
+            -------
+            float
+                in radians
+        """
+        deg = self.astral.solar_elevation(dateandtime = datetime,
+                                          latitude = self.location.lat,
+                                          longitude = self.location.lng)
+        return math.radians(deg)
+
+    def df(self, start, end):
+        """
+            Creates a dataframe with the insolation in W/m**2 in hourly resolution
+
+            Parameters
+            ----------
+            start, end: datetime.datetime
+
+            Returns
+            -------
+            Pandas Dataframe
+        """
+
+        hours = pd.date_range(start=start, end=end, freq='h')
+        gis = []
+        for hour in hours:
+            gis.append(self.globalIrradiance(hour))
+
+        df = pd.DataFrame(gis, index=hours, columns = ['insolation'])
+        return df.tz_localize('UTC')
+
+    def solarAzimuth(self, datetime):
+        """
+        Calculate the azimuth of the sun
+
+        :param datetime: datetime.datetime
+        :return: float
+            in radians
+        """
+
+        deg = self.astral.solar_azimuth(dateandtime=datetime,
+                                        latitude=self.location.lat,
+                                        longitude=self.location.lng)
+        return math.radians(deg)
+
+class PVModel(SolarInsolation):
+    """
+        Module that models a theoretically perfect PV installation,
+        extending the Solar Insolation Model, but adding PV orientation and tilt.
+    """
+
+    def __init__(self, location, orient=180, tilt=35):
+        """
+            Parameters
+            ----------
+            location: String
+            orient: number (optional, default=180 (south))
+                degrees (0-360)
+            tilt: number (optional, default=35)
+                degrees
+        """
+
+        super(PVModel, self).__init__(location = location)
+        self.orient = math.radians(orient)
+        self.tilt = math.radians(tilt)
+
+    def directIntensity(self, datetime):
+        """
+            Calculate the direct solar beam intensity for a given date and time,
+            but compensate for the PV orientation and tilt
+
+            Parameters
+            ----------
+            datetime: datetime.datetime
+
+            Returns
+            -------
+            float
+                in W/m**2
+        """
+        di = super(PVModel, self).directIntensity(datetime)
+        a = self.solarElevation(datetime)
+        b = self.tilt
+        c = self.orient
+        d = self.solarAzimuth(datetime)
+
+        PVdi = di * (math.cos(a)*math.sin(b)*math.cos(c-d) + math.sin(a)*math.cos(b))
+
+        #PVdi cannot be negative
+        return max(0, PVdi)
+
+    def globalIrradiance(self, datetime):
+        """
+            Calculate global solar irradiance for a given date and time
+            needed to override, because background irradiance is not influenced by PV orientation and tilt
+
+            Parameters
+            ----------
+            datetime: datetime.datetime
+
+            Returns
+            -------
+            float
+                in W/m**2
+        """
+        #calculate the direct intensity without influence of tilt and orientation
+        di = super(PVModel, self).directIntensity(datetime)
+
+        #add the tilted and oriented direct intensity to the background irradiance
+        return self.directIntensity(datetime) + self._backgroundIrradiance(di)

requirements.txt

@@ -16,4 +16,6 @@ python-coveralls
 coverage 
 pint
 beautifulsoup4
-iso8601
+iso8601
+geocoder
+astral