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Weather Station Hardware => What Weather Station Should I Buy? => Topic started by: s435weather on September 18, 2021, 09:12:15 PM

Title: Recommendation for adding UV and Solar Radiation sensor
Post by: s435weather on September 18, 2021, 09:12:15 PM
I currently own a Texas Weather Station (TWI) which does not measure UV and Solar Radiation. I would like to add the ability to monitor UV and Solar Radiation.  I know at some point my TWI is going to stop and it is unsupported except for this forum, but it still keeps chugging along after many years.

Any suggestion what I can purchase to just read those 2 readings without getting into a new PWS?  I thought about getting an Ecowitt just to add those readings, but seems a little overboard to add an entire station and maybe not quite accurate for reading UV and Solar Radiation at it's price point. Maybe someone sells UV standalone or separate add on?

Thanks
Title: Re: Recommendation for adding UV and Solar Radiation sensor
Post by: s435weather on September 18, 2021, 10:54:36 PM
I just realized that Ecowitt makes an almost standalone light sensor?
WS68 Wireless Solar Powered Anemometer with Light & UV Sensor
https://www.ecowitt.com/shop/goodsDetail/43 (https://www.ecowitt.com/shop/goodsDetail/43)

Paired along with a GW1000 to integrate with my TWI would give me an option at just over $100

Any comments on reliability or accuracy of the sensor?
Title: Re: Recommendation for adding UV and Solar Radiation sensor
Post by: Timbouk1 on September 20, 2021, 06:52:30 AM
Hi,
I've had a WS68 with the updated GW1100 installed here in the UK for just under a month and am very pleased with the reliability. If you went that route then when your TWI does pack up you just need to get the stand alone Ecowitt WH40 rain gauge (only £40 here) plus a WS32 temp & humidty sensor (£25) and you have the full array of instruments back up and running  :grin:
Title: Re: Recommendation for adding UV and Solar Radiation sensor
Post by: s435weather on September 20, 2021, 09:50:53 PM
I like that approach, that is a good idea. As I loose instruments from the  TWI, just add them to the Ecowitt. As inexpensive as the  Ecowitt  is, I might add the the gauges sooner then latter. I am replacing the humidity sensor on my TWI, good way to see if it is still working accurately.  Not sure about the longevity of the  Ecowitt , I guess time will tell.
Title: Re: Recommendation for adding UV and Solar Radiation sensor
Post by: Mandrake on September 30, 2021, 08:31:42 AM
The ecowitt stuff is latest generation and is getting better year on year.
They also have excellent support so if you do get unlucky they will usually look after you.
They are a rock solid company!

My own kit has been in field now several years without too much problem (only the soil moisture sensors have been a bit rough and they have mostly solved that issue)
Title: Re: Recommendation for adding UV and Solar Radiation sensor
Post by: davidefa on September 30, 2021, 09:59:35 AM
I have a ws65 ( so not sure this is 100% true for ws68 ).
The solar sensor of ws65 is a  lux-meter, the lux value is converted in W/m2, this is 'acceptable', but it is not a true solar radiation sensor.
There is no UV sensor, the UV reading is directly derived from the lux reading, I'd define this 'less than acceptable' for an 'UV sensor' ( I mean there is no 'uv information' in this value ).
Title: Re: Recommendation for adding UV and Solar Radiation sensor
Post by: Mandrake on October 12, 2021, 06:10:56 AM
Ecowitt/Fine Offset are thinking about a genuine UV sensor, but no promises or timelines.
Title: Re: Recommendation for adding UV and Solar Radiation sensor
Post by: davidefa on October 12, 2021, 09:43:01 AM
Yes not super easy to find such an uv sensor ( a low cost one ).
Those generally found on the market are narrow band one and using these to estimate uv on a wide band sounds like a gamble ( at least to me ).
The weatherflow tempest should use this sensor ( which has a light and a uv sensor ):
APDS-9200 ( obsoleted )
LTR-390UV ( replacement )
Title: Re: Recommendation for adding UV and Solar Radiation sensor
Post by: s435weather on October 19, 2021, 08:41:33 PM
Ecowitt/Fine Offset are thinking about a genuine UV sensor, but no promises or timelines.

I am not sure what you mean by a genuine UV sensor. Is the Ecowitt Light and UV Sensor not a genuine UV sensor?
Title: Re: Recommendation for adding UV and Solar Radiation sensor
Post by: Mandrake on October 22, 2021, 01:32:46 PM
No the majority of sensors are simply light meters that derive the theoretical UV value from an algorithm from the Lux value.
There is sensor parts that can actually measure true UV values but none that I am aware have been made into consumer grade weather enthusiast equipment....yet!
Title: Re: Recommendation for adding UV and Solar Radiation sensor
Post by: johnd on October 22, 2021, 02:06:00 PM
No the majority of sensors are simply light meters that derive the theoretical UV value from an algorithm from the Lux value.

In my book, trying to get away with deriving a UV value from a solar/light intensity value is close to fraud and demeans the whole product. It makes you wonder how many other corners have been cut in such toy/gadget stations.

Quote
There is sensor parts that can actually measure true UV values but none that I am aware have been made into consumer grade weather enthusiast equipment....yet!

Certainly there are sensor elements that have separate visible and UV photodiodes and that are available very cheaply, though they do need extra circuitry to generate photometric or radiometric values for their parent station. The spec sheets look good, but I've no idea how accurate or robust they actually are in the field. But as Mandrake says, for whatever reason these do not yet seem to be appearing in any products, whether consumer gadgets, prosumer for serious hobbyists or genuine professional sensors.
Title: Re: Recommendation for adding UV and Solar Radiation sensor
Post by: fkapp on October 22, 2021, 03:19:18 PM
No the majority of sensors are simply light meters that derive the theoretical UV value from an algorithm from the Lux value.

In my book, trying to get away with deriving a UV value from a solar/light intensity value is close to fraud and demeans the whole product. It makes you wonder how many other corners have been cut in such toy/gadget stations.

Quote
There is sensor parts that can actually measure true UV values but none that I am aware have been made into consumer grade weather enthusiast equipment....yet!

Certainly there are sensor elements that have separate visible and UV photodiodes and that are available very cheaply, though they do need extra circuitry to generate photometric or radiometric values for their parent station. The spec sheets look good, but I've no idea how accurate or robust they actually are in the field. But as Mandrake says, for whatever reason these do not yet seem to be appearing in any products, whether consumer gadgets, prosumer for serious hobbyists or genuine professional sensors.

If this is the case, what type of sensor does Davis use in the UV 6490?
Not a cheap sensor and now has me curious how this sensor measures and calculates UV, or if this is expensive sensor using similar method to calculate off solar.

Title: Re: Recommendation for adding UV and Solar Radiation sensor
Post by: johnd on October 22, 2021, 04:26:38 PM
Davis 6490 does indeed use an appropriate UV sensor. I don't know the exact sensor part number, but the description in the data sheet says: 'The transducer is a semiconductor photodiode that responds only to radiation in the region of interest (ie the Erythema Action Spectrum). The diffuser provides an excellent cosine response. With multiple hard-oxide coatings, the interference filter provides the Erythema Action spectral response. It is stable in the presence of heat and humidity.

It works well in the UV, but TBH is a relatively old sensor now (used to be part 7841 I think before it was reworked) and a newer, simpler and cheaper version would be good to see.
Title: Re: Recommendation for adding UV and Solar Radiation sensor
Post by: mcrossley on October 22, 2021, 05:52:02 PM
It is expensive, but a wide band interference filter will probably not be cheap either. I know the narrow band interference filters I have bought for astro use in the past are not cheap.
Title: Re: Recommendation for adding UV and Solar Radiation sensor
Post by: fkapp on October 22, 2021, 06:05:57 PM
Thanks for answering and confirming is good sensor.
Am happy with it as got this spring and helps on those days when is a bit overcast or on peak sun summer days remind that is higher than think in AM to remind the kids to put on sun screen.

I have not done a data side by side, but my some nearby ecowitt stations appear that a divide solar intensity by 100 is what is used for UV.  like i said havent done side by side data compare but typically how the uv and solar compare.