fix to pvlib/spa.py for issue pvlib#2077

Author: dgapitts

pvlib/spa.py

@@ -413,8 +413,10 @@ def julian_day_dt(year, month, day, hour, minute, second, microsecond):
     frac_of_day = (microsecond / 1e6 + (second + minute * 60 + hour * 3600)
                    ) * 1.0 / (3600*24)
     d = day + frac_of_day
-    jd = (int(365.25 * (year + 4716)) + int(30.6001 * (month + 1)) + d +
-          b - 1524.5)
+    jd = int(365.25 * (year + 4716)) + int(30.6001 * (month + 1)) + d - 1524.5
+    if jd > 2299160.0:
+        jd += b
+
     return jd