So the weewx python code says it is using the Ryan and Stolzenbach model, which has a few approximations that don't work well in some cases, and it looks like this is one of them.
I've attached a plot comparing 3 insolation models predicting global horizontal irradiation. Bird and Hulstrom 1991 Bras 1992 and Ryan and Stolzenbach 1972 B&H has a lot more parameters to account for, but I have just thrown in the date/location for Boston, using whatever parameters were in the spreadsheet, and come up with the following comparison. I used the B&H predictions for modelling my solar PV system and found it gives very close results - or at least it did before my system got a bit older. However R&S also gives results that aren't too bad in my location. I have the code in php, but no spare time at the moment to convert to python. On Tuesday, 22 December 2020 at 2:19:29 am UTC+10 t...@tom.org wrote: > kk, glad you corroborated my observations. I am no expert in this for > sure. I am just tired of all of the comments I get from visitors to the > website about how my readings exceed theoretical max. I could remove the > max, but that doesn't seem fun. > > I do not have the expertise to validate the way weewx calculates it nor am > I even competent in Python, but for those who may, here is a link to the > code: > > > https://github.com/weewx/weewx/blob/d91635f3bc429f906d1f084c6a6bc8ee09fa1a27/bin/weewx/wxformulas.py#L332 > > > > On Sunday, December 20, 2020 at 1:26:31 PM UTC-5 kk44...@gmail.com wrote: > >> I found that thread interesting, so I added the column "maxSolarRad", >> too. >> >> [image: dayradiation.png] >> Readings of the console and the WeatherLinkLive device are quite the >> same. And the readings of "radiation" are higher than "maxSolarRad". The >> values I upload to the local weather network are well in the range of other >> stations nearby. >> >> >> Greg Troxel schrieb am Sonntag, 20. Dezember 2020 um 17:58:01 UTC+1: >> >>> >>> Greg Troxel <g...@lexort.com> writes: >>> >>> > Can someone share how to add maxSolarRad (when it is in the db) to the >>> > graphs for the traditional skin? Can I graph radiation, max >>> (observed), >>> > and theory all at once, having three? >>> >>> The answer is to just add it and label it; it comes out in green after >>> radiation in blue and max in red. Pro Tip: add it after radiation_max, >>> which is the max of local observations, and don't stick the line after >>> the radiation_max header and the 4 lines defining how max should be. >>> >>> >>> [[[dayradiation]]] >>> [[[[radiation]]]] >>> [[[[radiation_max]]]] >>> data_type = radiation >>> aggregate_type = max >>> aggregate_interval = 3600 >>> label = max >>> [[[[maxSolarRad]]]] >>> label = theory >>> >> -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to weewx-user+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/weewx-user/1bf064d3-bac9-4ed0-928c-5730d7af051bn%40googlegroups.com.
