Merge pull request #537 from NREL/feb_29_hacky_fix

Enable leap day to be included in PV simulations using weather data

shared/lib_util.cpp

@@ -902,15 +902,19 @@ size_t util::hour_of_year(size_t month, size_t day, size_t hour)
 	size_t h = 0;
 	bool ok = true;
 	std::vector<size_t> days_in_months = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
+    //first add the days from all the preceding completed months
 	if (month >= 1 && month <= 12)
 	{
 		for (size_t m = 0; m < (month - 1); m++)
 			h += days_in_months[m] * 24;
 	}
 	else ok = false;
-	if (day >= 1 && day <= days_in_months[month - 1])
-		h += (day - 1) * 24;
-	else ok = false;
+    //then add days in the current month up to the current day
+    if (day >= 1 && day <= days_in_months[month - 1])
+        h += (day - 1) * 24;
+    else if (month == 2 && day == 29) //special check for leap day present in data
+        h += (27 * 24); //for leap day, repeat Feb 28 in annual indexes, because hour_of_year is used to index 8760 non-leap-year arrays.
+    else ok = false;
 	if (hour >= 0 && hour <= 23)
 		h += hour;
 	else ok = false;

ssc/common.cpp

@@ -1222,28 +1222,39 @@ double shading_factor_calculator::dc_shade_factor()
 //HOWEVER, the year value may vary (i.e., TMY) so only checking month, day, hour, minute timesteps, not actual year vector
 bool weatherdata::check_continuous_single_year(bool leapyear)
 {
+    //first, set up some timestep variables
 	int ts_per_hour = 0; //determine the number of timesteps in each hour
 	if (leapyear)
 		ts_per_hour = (int)(m_nRecords / 8784);
 	else
 		ts_per_hour = (int)(m_nRecords / 8760);
 	double ts_min = 60. / ts_per_hour; //determine the number of minutes of each timestep
+
+    //next, check if the data has leap day (feb 29). need to do this because some tools pass in 8760 data that contains feb 29 and not dec 31
+    bool has_leapday = false;
+    int leapDayNoon = 1429 * ts_per_hour; //look for the index of noon on leap day. noon on leap day is hour 1429 of the year
+    if (this->m_data[leapDayNoon]->month == 2 && this->m_data[leapDayNoon]->day == 29) //check noon on what would be feb 29 if it's in the data
+        has_leapday = true;
+
+    //last, go through each index in order and make sure that the timestamps all correspond to a single, serially complete year with even timesteps
 	int idx = 0; // index to keep track of where we are in the timestamp vectors
-	// now, check that the month, hour, day, and minute vectors are consistent with a single, continuous year with an
-	// even timestep that starts on jan 1 and ends dec 31
 	for (int m = 1; m <= 12; m++)
 	{
 		int daymax = util::days_in_month(m - 1);
-		if (m == 2 && leapyear) daymax = 29; //make sure to account for leap day in Feb
+		if (m == 2 && has_leapday) daymax = 29; //make sure to account for leap day in Feb if it's in the data
+        if (m == 12 && has_leapday && !leapyear) daymax = 30; //if the data is 8760 but has Feb 29, then it won't have Dec 31
 		for (int d = 1; d <= daymax; d++)
 		{
 			for (int h = 0; h < 24; h++)
 			{
 				double min = this->m_data[idx]->minute;
 				for (int tsph = 0; tsph < ts_per_hour; tsph++)
 				{
-					min += tsph * ts_min;
-					//if any of the month, day, hour, or minute don't line up with what we've calculated, then it doesn't fit our criteria for a continuous year
+                    //first check that the index isn't out of bounds
+                    if (idx > m_nRecords - 1)
+                        return false;
+                    //if any of the month, day, hour, or minute don't line up with what we've calculated, then it doesn't fit our criteria for a continuous year
+                    min += tsph * ts_min;
 					if (this->m_data[idx]->month != m || this->m_data[idx]->day != d || this->m_data[idx]->hour != h
 					    || this->m_data[idx]->minute != min)
 						return false;