And then I forgot the attachment!
On Wednesday, 23 December 2020 at 7:18:31 pm UTC+10 Cameron D wrote: > I should have looked a bit more closely before posting! I used the solrad > excel code from Uni Washington. > I had adjusted my B&H parameters to represent quite clean air but forgot > to match the Bras and RS code from default. > If I: > > 1. reset the BH turbidity params to default, > 2. adjust the Bras param down to 1.6 and > 3. adjust the RS param to 0.84, > > then the curves are close to normalised at peak. The RS curve is still a > somewhat poor representation at dawn and dusk, while Bras is probably close > enough to BH that it's not worth the extra effort. > The main advantage with B&H is the atmospheric moisture, which I think > contributes significantly, but differently from the atmospheric turbidity > parameters and changes the shape of the curve. So a single parameter cannot > account for all variables. > The safest bet might be to adjust the parameter for clear skies and then > say that is an upper limit. > > On Wednesday, 23 December 2020 at 6:31:47 pm UTC+10 Cameron D wrote: > >> 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/ef4b8a0b-110b-4e48-bb2e-50ebae8c8277n%40googlegroups.com.
