Solar readings from Ecowitt WS68

Hardware Weather Station Equipment
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1

First decent blue-sky day since I installed my WS68. . . beautiful graphs:

ecowitt
ecowitt610×295 13.8 KB

WU
WU597×201 8 KB

PWS
PWS566×168 7.98 KB

Only problem is Ecowitt says max 506, WU and PWSweather say 452 W/m2.

WD (which is uploading to WU and PWSweather) calculated max 434, and a VP2 (admittedly an old one) about half a mile away has 570 W/m2.

VP2
VP2596×208 10.5 KB

So why the difference between ecowitt.net and WD uploads? WD gets the same readings from the GW2000 as ecowitt.net

2

Comparing Ecowitt and Davis solar sensors is iffy to start with as all the Ecowitt ones actually calculate W/m² from a sensor outputting a Lux reading! I was lucky with my WS80 as I ran in parallel with my VP1 for some months in summer and was able to adjust the WS80 calibration factor to compare reasonably with my Davis solar sensor. The UV levels are also an approximation from Ecowitt using the solar sensor!

As I’m sure you know WD has some fudge factors as well for solar which can again confuse things if both WD and the WS68 have adjustments!

I no longer run WD so cannot comment on how it handles solar now!

Stuart

3

Thanks, Stuart.

I must admit I was pleasantly surprised that the Ecowitt figure was not even higher, because I have seen well over 1,000 W/m2 on “fine-weather-cloud” days, much higher than I would expect from cloud enhancement and theoretically impossible here.

I didn’t know solar was calculated from lux. . . I did know that UV was calculated, and I have a “calibration” factor of 0.6 for that: I was able to compare it with a nearly-new WMR200 sensor.

But the problem remains: WD and ecowitt get the same readings from the GW2000 and WD seems to send different numbers to WU and PWSweather.

4

Well I can’t explain that but my views about WD and solar are that in recent years I didn’t trust it and it seems like there is an issue!

Stuart

5

I set a “calibration” factor of 0.9 for solar. . . but I have to admit that was based on WD calculations of max solar.

I’d forgotten your calculator, Stuart :roll_eyes:

Not so important now as we head towards the solstice, when the sun only crawls 11° above the horizon here.

BTW I got this from Ecowitt support: “The gain setting of solar won’t affect the UV, they are independent, thus you can set each without considering the relation between them.”