Re: [weewx-development] Where does the crt extension get the value for SolarMax?

['John Kline' via weewx-development]

Search for: Ryan-Stolzenbach vs. Bras for estimating clear sky solar radiation On Dec 1, 2025, at 9:21 PM, John Smith <deltafoxtrot...@gmail.com> wrote:  Any idea what the difference between the 2 formulas in weeWX would be? wxformulas.py links to a page with an excel spreadsheet which seems to use macros instead of just formulas, but LibreOffice blocked them on security grounds. The spreadsheet seems to have 4 models Searching for solar radiation maximum "bras" didn't exactly turn up anything relevant... On Tue, 2 Dec 2025 at 15:38, 'John Kline' via weewx-development <weewx-development@googlegroups.com> wrote: maxSolarRad defaults to hardware preferred.  Assuming it is not supplied by the driver, it is calculated in wxxtypes.py The function is below.  Note that the default for maxSolarRad_algo is ‘rs’.     def calc_maxSolarRad(self, key, data, db_manager):         altitude_m = weewx.units.convert(self.altitude_vt, 'meter')[0]         if self.maxSolarRad_algo == 'bras':             val = weewx.wxformulas.solar_rad_Bras(self.latitude_f, self.longitude_f, altitude_m,                                                   data['dateTime'], self.nfac)         elif self.maxSolarRad_algo == 'rs':             val = weewx.wxformulas.solar_rad_RS(self.latitude_f, self.longitude_f, altitude_m,                                                 data['dateTime'], self.atc)         else:             raise weewx.ViolatedPrecondition("Unknown solar algorithm '%s'"                                              % self.maxSolarRad_algo)         return ValueTuple(val, 'watt_per_meter_squared', 'group_radiation') wxformulas.py: solar_rad_RS:    from weewx.almanac import Almanac     if atc < 0.7 or atc > 0.91:         atc = 0.8     if ts is None:         ts = time.time()     sr = 0.0     try:         alm = Almanac(ts, lat, lon, altitude_m)         el = alm.sun.alt  # solar elevation degrees from horizon         R = alm.sun.earth_distance         z = altitude_m         nrel = 1367.0  # NREL solar constant, W/m^2         sinal = math.sin(math.radians(el))         if sinal >= 0:  # sun must be above horizon             rm = math.pow((288.0 - 0.0065 * z) / 288.0, 5.256) \                  / (sinal + 0.15 * math.pow(el + 3.885, -1.253))             toa = nrel * sinal / (R * R)             sr = toa * math.pow(atc, rm)     except (AttributeError, ValueError, OverflowError):         sr = None     return sr On Dec 1, 2025, at 8:19 PM, John Smith <deltafoxtrot...@gmail.com> wrote:  On Tue, 2 Dec 2025 at 14:14, 'Peter Fletcher' via weewx-development <weewx-development@googlegroups.com> wrote: No. The logic of the crt code implies that it is a theoretical max value, and the actual values reported in realtime.txt are consistent with this. What's it based on, latitude?  -- You received this message because you are subscribed to the Google Groups "weewx-development" group. To unsubscribe from this group and stop receiving emails from it, send an email to weewx-development+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/weewx-development/CAGTinV4dWNWAJixkt1CUoumcoDXwFEQow-s-nR7Hq5bdBUxPgA%40mail.gmail.com. -- You received this message because you are subscribed to the Google Groups "weewx-development" group. To unsubscribe from this group and stop receiving emails from it, send an email to weewx-development+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/weewx-development/73AA04EB-0937-407C-A00E-F577D49A79EA%40johnkline.com. -- You received this message because you are subscribed to the Google Groups "weewx-development" group. To unsubscribe from this group and stop receiving emails from it, send an email to weewx-development+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/weewx-development/A3B77189-16D4-420D-9DB4-CA8C976E917E%40johnkline.com.