Author Topic: Solar radiation sensor, why and what  (Read 6411 times)

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Offline cabud

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Solar radiation sensor, why and what
« on: April 25, 2018, 06:22:52 PM »
Hello, I joined to ask this question. New member, hopefully life member in the making. I am an industrial controls engineer, wanting to get into weather tracking. I have some projects at hydro-electric power stations that have me interested in weather telemetry.

My question at the moment is regarding the solar radiation and UV sensors available with some brands. I can't find what these are for, why they might be useful, and if I might appreciate having these sensors even if I don't understand them now. I am an avid gardener, would I use it for that?

Also, If I post to the CWOP, and other web services, are these Solar and UV sensors providing data that they would find useful, even if I don't? Thanks

Offline DaleReid

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Re: Solar radiation sensor, why and what
« Reply #1 on: April 25, 2018, 09:29:25 PM »
From my point of view, there are those who have mainly Davis stations with their easily available add-ons or more complete stations with at least the solar sensor on them.
Sometimes it seems like solar values are just one more thing about our weather to measure and record.  Other times it is used to help calculate evaporation losses, so I'm thinking the ag users would be more interested.  Other times it does help estimate hours of sunlight, for growing, solar power generation,and so on.

Me?  I glance at my graph and get a good idea of whether the skies were clear, partly cloudy, what time of day and all that. Just using as my 'sunshine indicator' for which there are other but not integrated devices. 

Hope it helps your awareness.
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Offline BeaverMeadow

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Re: Solar radiation sensor, why and what
« Reply #2 on: April 25, 2018, 10:45:03 PM »
...My question at the moment is regarding the solar radiation and UV sensors available with some brands. I can't find what these are for, why they might be useful, and if I might appreciate having these sensors even if I don't understand them now.......

Knowing UV is valuable as it is potentially carcinogenic.

Offline SLOweather

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Re: Solar radiation sensor, why and what
« Reply #3 on: April 25, 2018, 11:57:15 PM »
With the solar sensor, the console will calculate evapotranspiration (ET), or how much water evaporates from the soil, and how much is transpired by grass. With that number, especially summed over a week, it's easy to make informed watering decisions.

Offline Intheswamp

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Re: Solar radiation sensor, why and what
« Reply #4 on: April 26, 2018, 10:13:06 AM »
...My question at the moment is regarding the solar radiation and UV sensors available with some brands. I can't find what these are for, why they might be useful, and if I might appreciate having these sensors even if I don't understand them now.......

Knowing UV is valuable as it is potentially carcinogenic.
I agree with the danger of UV exposure, but most folks old enough to set up a PWS or to surf to a website and read UV data can pretty well tell if the UV index requires a hat, sunscreen, or whatever, without having to look at data on a PWS.  They're nice to have but I can't see that they will really help protect someone from UV exposure.  If you walk out and feel the sun hitting you significantly then a person needs to take precautions if they are so inclined.

Solar, as has been noted, is good for irrigation purposes and for solar electric uses.  I do believe that the more "bang for the buck" is the solar sensor.

cabud, if you are considering a Davis VP2 and are considering the solar and uv sensors I *strongly* recommend going ahead with the VP2+ that includes these two sensors.  You will never find the sensors as inexpensive as you will find them in the VP2+.  Adding them later *is definitely* more expensive. 

Best wishes,
Ed

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Offline DoctorKnow

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Re: Solar radiation sensor, why and what
« Reply #5 on: April 26, 2018, 11:11:27 AM »
cabud,

The Fine offset weather stations like a WH-2310, (mine is Excelvan) calculate UV/light and is very accurate. The station is very affordable as well. If you get it report back and I'll give you some pointers on it, or just look in Ambient weather folder on this site, as I wrote about it several times in there.

Offline PaulMy

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Re: Solar radiation sensor, why and what
« Reply #6 on: April 26, 2018, 11:13:26 AM »
Quote
With the solar sensor, the console will calculate evapotranspiration (ET), or how much water evaporates from the soil, and how much is transpired by grass. With that number, especially summed over a week, it's easy to make informed watering decisions. 
Quote
cabud, if you are considering a Davis VP2 and are considering the solar and uv sensors I *strongly* recommend going ahead with the VP2+ that includes these two sensors.  You will never find the sensors as inexpensive as you will find them in the VP2+.  Adding them later *is definitely* more expensive. 

As you may have seen on another thread, after 10 years I have decided to replace my VP2 ISS and have ordered the VP2 Plus w/24FARS ISS.  Looking forward to having it working, and do some sunshine comparison to my B-L sunrecorder and see if it will help my lawn watering schedule.

http://www.sunrecorder.net/sr-around-the-world/ and http://www.komokaweather.com/weather/sunrecorder/sunrecorder_display_v2_today.html

Enjoy,
Paul

Offline cabud

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Re: Solar radiation sensor, why and what
« Reply #7 on: April 26, 2018, 11:27:32 AM »
cabud,

The Fine offset weather stations like a WH-2310, (mine is Excelvan) calculate UV/light and is very accurate. The station is very affordable as well. If you get it report back and I'll give you some pointers on it, or just look in Ambient weather folder on this site, as I wrote about it several times in there.

Thanks for the recommendation. I am a mechanical and electrical engineer, and have qualms about the cheap units....doesn't mean the qualms are justified. I have been researching these for several years now.

We have a nearly constant very light breeze, I want something that will register that without having to lube it ar baby it. Do these cheap WS register very light breeze ?

Offline cabud

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Re: Solar radiation sensor, why and what
« Reply #8 on: April 26, 2018, 11:31:08 AM »
Quote
With the solar sensor, the console will calculate evapotranspiration (ET), or how much water evaporates from the soil, and how much is transpired by grass. With that number, especially summed over a week, it's easy to make informed watering decisions. 
Quote
cabud, if you are considering a Davis VP2 and are considering the solar and uv sensors I *strongly* recommend going ahead with the VP2+ that includes these two sensors.  You will never find the sensors as inexpensive as you will find them in the VP2+.  Adding them later *is definitely* more expensive. 

As you may have seen on another thread, after 10 years I have decided to replace my VP2 ISS and have ordered the VP2 Plus w/24FARS ISS.  Looking forward to having it working, and do some sunshine comparison to my B-L sunrecorder and see if it will help my lawn watering schedule.

http://www.sunrecorder.net/sr-around-the-world/ and http://www.komokaweather.com/weather/sunrecorder/sunrecorder_display_v2_today.html

Enjoy,
Paul

Paul, thanks for the practical use scenario, I am mostly interested in that exact unit, but need to understand the value before spending the cash. Can you explain how you would use the sun sensors for helping with the watering schedule? Wouldn't it also be useful to have soil temp and moisture sensors? I am mostly interested in this to augment our large vegetable gardens. Our lawn is another story, nothing to look at there  :?

Offline PaulMy

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Re: Solar radiation sensor, why and what
« Reply #9 on: April 26, 2018, 11:46:45 AM »
I was just quoting SLOweather and have no knowledge or experience as yet. 

I pride my lawn (1/2 Ac) and try to keep it green during the summer.  And during the dry summer months have been using a timer for watering 3 hours each morning and another 3 hours late afternoon which covers about 20% of the lawn each day (I manually change the sprinkler hoses twice a day) but have been considering getting a built-in sprinkler system.  Fortunately I don't use metered water for watering as we have fairly good ground water supply and use my own well - electricity cost is another thing!

Enjoy,
Paul 

Offline DoctorKnow

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Re: Solar radiation sensor, why and what
« Reply #10 on: April 26, 2018, 12:00:40 PM »
cabud,

The Fine offset weather stations like a WH-2310, (mine is Excelvan) calculate UV/light and is very accurate. The station is very affordable as well. If you get it report back and I'll give you some pointers on it, or just look in Ambient weather folder on this site, as I wrote about it several times in there.

Thanks for the recommendation. I am a mechanical and electrical engineer, and have qualms about the cheap units....doesn't mean the qualms are justified. I have been researching these for several years now.

We have a nearly constant very light breeze, I want something that will register that without having to lube it ar baby it. Do these cheap WS register very light breeze ?

I have never lubed mine, and it is the most sensitive anemometer I have used, and I have used Oregon Scientific, Acurite, and the wh-2310. Also look at the WH-3080 station if you want to upload to the internet sites. It works with Cumulus software, the WH-2310 works with meteobridge for sure. I do not like the software that comes with the stations themselves.

Offline SLOweather

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Re: Solar radiation sensor, why and what
« Reply #11 on: April 26, 2018, 02:07:28 PM »
RE: ET from a solar sensor and irrigation. There are 2 ways to use it.

The ET output from a Davis console is summed over 24 hours from midnight.



Sum the 7 day daily max ETs and get a good estimate of the amount of water you should irrigate next week in inches.

I developed that and called it the Irrigation Index.

Then I found that the California DWR had developed the Watering Index. To use it you need the above summed daily ETs, as well as the highest average weekly ET for your location, and an irrigation timer with a Percent adjustment.

Set your controller to water the amount of the highest average weekly ET.

Then, the current controller percentage setting = (Last 7 Days ET/highest average weekly ET) x 100. Note that for a hot, dry, windy week, the setting can be > 100%.

Also, I modified that DWR index to include last 7 days rain for SLOweather.com.  ((Last 7 Days ET-Last 7 days rain)/highest average weekly ET) x 100

Note that this modification can go negative. I wrote a PHP script to do those calcs for display on SLOweather.com. I think my Irrigation Index also includes the last 7 days rain as well.

Here's a grab of today's Indexes:




Offline cabud

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Re: Solar radiation sensor, why and what
« Reply #12 on: April 27, 2018, 07:05:35 PM »
Thank you all very much for the answers and replies, it is helpful.

I was going to purchase a Davis Vantage Pro, but now there is the member from Poland coming out with a WiFi interface for the Vantage, so I will wait until it is available for purchase.

Offline CW2274

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Re: Solar radiation sensor, why and what
« Reply #13 on: April 27, 2018, 07:20:30 PM »
I was going to purchase a Davis Vantage Pro, but now there is the member from Poland coming out with a WiFi interface for the Vantage, so I will wait until it is available for purchase.
Why wait? They have nothing to do with each other as they are a separate purchase, unless your guy is a Davis dealer. Get the WiFi when it becomes available and enjoy your VP2 in the mean time.

Offline CW2274

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Re: Solar radiation sensor, why and what
« Reply #14 on: April 27, 2018, 07:31:11 PM »
I was going to purchase a Davis Vantage Pro, but now there is the member from Poland coming out with a WiFi interface for the Vantage, so I will wait until it is available for purchase.
Why wait? They have nothing to do with each other as they are a separate purchase, unless your guy is a Davis dealer. Get the WiFi when it becomes available and enjoy your VP2 in the mean time.

Well....becuz....we have a small rented place, and the internet connection and router is in the garage, I have a wifi range extender in the house....the Davis hookup would involve extra equipment, since I want the console in the house, and there is only WiFi, and no PC or anything. This little device will solve my connection conundrum. Quite splendid.
The point I'm getting at is that you can still have your VP2 up and running for YOU. I owned mine for about 4 years before getting it on-line.

Offline Skywatch

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Re: Solar radiation sensor, why and what
« Reply #15 on: April 30, 2018, 10:27:12 PM »
I'm gonna throw my hat into this conversation.

I have both the Vantage Pro2 plus and Fine Offset (Excelvan) WH-2310 that Dr. Know mentioned. Honestly I can't imagine being without Solar or light intensity measurement. But I think newbies have a hard time understanding light intensity because it's not common meteorological measurement that the public is familiar with. They don't show solar on the news and they rarely show it on most weather sites.

To be honest I didn't realize how valuable the information is until I added solar radiation to my VP2 and now I wouldn't be without it. DaleReid pretty much summed up the same reasons I have.

I will say that as far as how it's read varies from station to station. The Davis VP2+ displays it in Watts per square meter (Wm/2). The Fine Offset stations change between Watts per square meter, Lux/Killolux, and Footcandles.

Some info on the unit usage,

Wm/2 Irradiance, https://en.m.wikipedia.org/wiki/Irradiance
Lux Illuminance https://en.m.wikipedia.org/wiki/Illuminance
Footcandles (fc) https://en.m.wikipedia.org/wiki/Foot-candle

As far as station models, like I said I have both Davis Vantage Pro2 plus and Fine Offset WH-2310 and both are great stations although you do get what you pay for in terms of longevity.

If you're on a budget of let's say less than 200$, the WH-2310 is an excellent weather station. Actually like Dr. Know I too have had Oregon Scientific, Lacrosse, and Acu-rite and I will say that the WH-2310 is probably the best budget level stations I've personally owned with or without solar data.

And of course the Vantage Pro2, there's no shortage of folks here who are happy owners myself included.

If you're looking for advice on weather stations I'd suggest visiting this part of the forum, https://www.wxforum.net/index.php?board=71.0

Hope this helps.
I live in an apartment and for the moment am not a home weather watcher.

I am a storm chaser.

Offline cabud

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Re: Solar radiation sensor, why and what
« Reply #16 on: May 01, 2018, 05:22:27 PM »
I'm gonna throw my hat into this conversation.

I have both the Vantage Pro2 plus and Fine Offset (Excelvan) WH-2310 that Dr. Know mentioned. Honestly I can't imagine being without Solar or light intensity measurement. But I think newbies have a hard time understanding light intensity because it's not common meteorological measurement that the public is familiar with. They don't show solar on the news and they rarely show it on most weather sites.



Hope this helps.

This is basically what you have? I don't see much other option to buy in USA

https://www.aliexpress.com/store/product/MISOL-professional-weather-station-wind-speed-wind-direction-rain-meter-pressure-temperature-humidity-UV/2024020_32790333971.html

This says it has the solar sensors

Offline Skywatch

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I live in an apartment and for the moment am not a home weather watcher.

I am a storm chaser.

Offline Skywatch

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Re: Solar radiation sensor, why and what
« Reply #18 on: May 01, 2018, 07:22:56 PM »
The oval item on top of the the temperature/humidity/transmitter (the pagoda looking thing) contains the solar sensor. To the right of the solar cell there's a little white bubble. That's the solar sensor. On the other side of the solar cell is a circle that appears to be melted in by the manufacturer. Under that is the UV sensor. On the display the solar and UV is displayed in the top right corner of the screen.
I live in an apartment and for the moment am not a home weather watcher.

I am a storm chaser.

Offline cabud

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Re: Solar radiation sensor, why and what
« Reply #19 on: May 02, 2018, 09:46:00 AM »
Thank you so much for all the info, I am looking at the unit you recommended, it's hard to believe it actually works.

I live in Northern Wisconsin, with harsh winters. I'm one of those people that regrets just about every cheap purchase I've made.

The reviews are so spotty for this device...Is this comment about the USB still the case?

https://www.wxforum.net/index.php?topic=32128.msg324292#msg324292

My main use for this is to upload to online site, need good connection, the USB issue has me concerned, as many have reported issues with it. Can you elaborate? Thanks!
« Last Edit: May 02, 2018, 10:04:19 AM by cabud »

Offline DoctorKnow

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Re: Solar radiation sensor, why and what
« Reply #20 on: May 02, 2018, 10:05:10 AM »
I put a ferrite choke on mine, adjusted the display and outdoor transmitter locations just a bit from where I had them originally placed, and the issue of USB hanging up went away. I don't think it was the USB at all actually, I think the signal was a little too weak and would not be received and that caused the loss of data. Those reviewers who gave poor results, I don't think they understood what they were doing... The directions are rather vague as to all the features and options for installation, also calibrations. The only thing I wish was different was the update interval on the wind reading, (48 sec) however, the transmitter is constantly taking a reading during that time, and sends out the steady wind speed and gusts of that interval every 48 secs along with temp/humidity and rain. Solar is around every 55 secs.

Here is my NWS feed. You can see it is working properly. I have it set for every 10 min. If the connection was dropping, it would be sending at shorter and longer periods,  and not exactly 10 min like you see here. Also where rain is 0.00 would be blank.

https://www.wrh.noaa.gov/mesowest/timeseries.php?sid=E5945&num=48


Offline cabud

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Re: Solar radiation sensor, why and what
« Reply #21 on: May 02, 2018, 03:30:51 PM »
https://www.amazon.com/Excelvan-Professional-Wireless-Internet-Temperature/dp/B01E36FXJ4
Try this.

Ordered one. Seems way too cheap to be any good, but this will be my initiation to weather stations!

I am a lifelong electrical and mechanical automation engineer, so I will have fun with it.

Where do you guys get replacement parts for these?

I plan to get up and running, then do a RasPi with Weewx / Cumulus MX for the net side of things. A bit of research yet for what software to use.

Perhaps we're getting off topic for the thread, it was about the solar sensors, and this unit has them.
« Last Edit: May 02, 2018, 05:59:43 PM by cabud »

Offline DoctorKnow

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Re: Solar radiation sensor, why and what
« Reply #22 on: May 02, 2018, 06:30:25 PM »
Let us know when you get going. You got this one for a good price. I paid 30 more.

Offline cabud

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Re: Solar radiation sensor, why and what
« Reply #23 on: May 03, 2018, 12:44:33 PM »
Let us know when you get going. You got this one for a good price. I paid 30 more.

I sure will! Excited about it

Can someone post a picture of the USB cable for these Fine Offset stations? I'd like to get a shielded cable with ferrites ordered ahead of time, need to know the type of USB ends it needs. Thanks

Offline DoctorKnow

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Re: Solar radiation sensor, why and what
« Reply #24 on: May 03, 2018, 01:58:15 PM »
It is the really small USB. I am using the cable from my old Oregon station.
« Last Edit: May 03, 2018, 02:01:48 PM by DoctorKnow »