Topic: VP2/ISS adding UV and solar sensors

[JRHill]

I've had the equipment for 12 years and have really enjoyed the hardware. Weatherlink not so much in the past but a month ago I installed the latest rev and it is working much better than before. A year ago I sent the ISS in for the refresh and what a wonderful service. The wind speed and direction were acting up and the battery would go low because the Solar screen was so UV fogged. They did an excellent rebuild!

So because the unit has run so well over the years I decided to add the solar sensor. I purchased the bracket and sensor and shortly afterward realized I ordered the UV sensor in error. Oops. So I ordered the solar sensor and now have both. I'll be mounting the add-ons today when it quits raining....

My question(s): I have learned that the these sensors drift over time. Particularly the UV? So why the drift that will require an expensive calibration after over a year? Is it a slow degeneration of the sensor? If so, what is the lifespan before its out of calibration range? I understand this would vary by location - I'm asking generally. Also, I believe the calibration is a corrective offset for the sensor. How does a single offset correct the whole range between low to high? I am just trying to plan for the future as it does no good to compare year to year when there is that error. Please help me understand what I have gotten myself into.

BTW, we are off grid and power is 3kw of solar. So in a way I already have a solar sensing but it is not correlated to weather and when the batteries are full the charge controller shuts down and so goes any sensing. It'll be interesting to compare the readings with the weather.

TIA, JRH

[TraderGary]

My plan is to purchase a second set of sensors, both Solar and UV, at the end of my second year of ownership. I am now 9 months into my original purchase.

Then at the end of the second year, I will swap out my Solar and UV sensors and send in the old sensors for recalibration.

Every two years I will do the same swap exercise. This way I will never be without Solar and UV sensors.

[JRHill]

That would seem an expensive proposition considering the cost to celebrate the sensors vs just sending the ISS in for a rebuild? It seems they recalibrate them at a ISS rebuild. Maybe not with certifications but I doubt there is much difference.

So again I ask, how do they drift?

[JRHill]

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[JRHill]

Sorry about the duplicate. I tried to fix it. The satellite connection is constipated.

[azchrisf]

There is likely some component inside the sensor that deteriorates due to the UV or electricity itself, or the lens. What, exactly, I don't think many of us know.
I don't believe there is any real "recalibration" per say, they just replace the sensor and send you a new one.
They would need some form of a reprogrammable controller chip inside the unit to store a calibration and drift table, and I am unsure if it even has one but doesn't seem like it. Even if it's the lens that's soldered too. Probably one of those $10 units they charge $300 for....case in point the FARS board - has connectors, 2 resistors, and a diode. Costs maybe a quarter to make. And they charge you $40.

I had mine out in strong Arizona sun for about 2 and a half years before I started to notice degradation. It just depends bud, some see many years some see as little as a year. Davis actually recommends sending it in for recalibration every year (or is it two? Someone correct me...).

But either way, having another on hand for quick change outs if you are a weather buff or interested in always sending correct data to CWOP, is a good idea.

Also, I believe I posted the cost (email from Davis) on sending in just the sensors. I dunno if it's less than a full system refurb.

[JRHill]

TY Sir. Just gathering info. I am not uploading to CWOP yet. Thinking about it.

So the closest weather facility is Pendleton, OR. Its a few hours away. But on a clear day can't I use their readings for an offset? I haven't looked into the details but why not?

[azchrisf]

Absolutely not - never use any offsets for UV or Solar. It will not be correct ever, if it's even possible...
For example, just using one point in time: There may be cloud cover (even on a relatively clear day, high level cloud cover) above the other sensor, and not at yours. Well your now +/- your correction factor vs. true reading +/- the degradation (of which we can't be sure is even x) for this point in time at your location. Same goes for a average. We also may (this is beyond my area of expertise) have differences in the Ozone layer, etc. allowing more or less UV at your location, etc. vs theirs, even with a mile, a pocket/density can make much difference even if it's non-linear and changing.

Weather is very complex science.

You have to replace or refurb the sensor. No way around it.

[JRHill]

OK, I understand. It would seem that at some intervals the ISS goes in for a refurb. I already know that is a great deal and they recal the sensors too. Thanks for your input.

[azchrisf]

No prob. Always good to ask questions my friend!
Not exactly "intervals", it's a good idea if you have the financial ability to stay ahead of any degradation and failures, or you can just when you notice a degraded component. Most do it when one fails, but if you are interested in "correct" data as I am, and as I feel anyone who owns a Weather Station AND reports to CWOP should, always monitor their station every day and check data over time for any problems.

[JRHill]

We are so off and remote I'm not sure anyone cares about our weather except for us. The one thing is the wildfire stuff. That's a whole other issue.

[archae86]

I added solar and UV sensors in January 2012. The solar sensor is now 10 years old and has not shown meaningful degradation. Yes I could tell if there were, with the clear skies in New Mexico here I get a chance to observe the year-round error in the correction that Cumulus makes for annual variation in the expected clear sky insolation. I tuned the Cumulus solar correction so that the error is about zero in near both equinoxes.  While it stays there I deem that sensor not degraded.

My original UV sensor lost sensitivity over the years. It was not a steady degradation and became pretty severe (something like 40%) in the last year or two before I replaced it. That was four years ago and the replacement has not yet changed sensitivity meaningfully.  At that time Davis offered me a hot-swap "refurbished" (looked new to me) unit for much less than the new unit price.

I suspect a constant degradation rate is not a very good model for the real-world behavior.  Monitoring is not only possible, but necessary.

[jerryg]

Let me tell you about my little experience with a new UV sensor, i wanted to get one to go with my solar and finally got enough money saved to order one along with the mounting kit for both sensors. Well i got it in and mounted and was a happy camper until i found a used station for sell at a great price. I knew it was pretty old and probably needed to be sent in for refurb but i had a spare fars iss so just wanted the console for a spare. Well when the station got here it had the UV and solar sensors with it, wow a bonus. I sent the sensors into Davis for refurb and when i got them back i put them in use with the backup station with the old mounting kit and to my surprise the refurb UV was reading 1.8 higher than the new one, i called Davis and asked why the refurb i just got back was reading higher and they told me to send the new one to them and they would check the calibration on it. Well after a couple of weeks i got it back and to my surprise it read the same as the refurb, so a new sensor was out of calibration out of the box. Just shows new does not mean it is right.

[azchrisf]

Let me tell you about my little experience with a new UV sensor, i wanted to get one to go with my solar and finally got enough money saved to order one along with the mounting kit for both sensors. Well i got it in and mounted and was a happy camper until i found a used station for sell at a great price. I knew it was pretty old and probably needed to be sent in for refurb but i had a spare fars iss so just wanted the console for a spare. Well when the station got here it had the UV and solar sensors with it, wow a bonus. I sent the sensors into Davis for refurb and when i got them back i put them in use with the backup station with the old mounting kit and to my surprise the refurb UV was reading 1.8 higher than the new one, i called Davis and asked why the refurb i just got back was reading higher and they told me to send the new one to them and they would check the calibration on it. Well after a couple of weeks i got it back and to my surprise it read the same as the refurb, so a new sensor was out of calibration out of the box. Just shows new does not mean it is right.

Same goes for the rain gauges from what we've seen...

[JRHill]

I've been uploading to WeatherLink for two months now. Everywhere I look I can not find any place what is utilizing my data. There still is not something I'm understanding about the setup. My goals are 1) to have my data be cloud based so there is a history, and 2) a source for neighbors to see the weather real time as the area forecasts are often well off for our canyon.

Recap: round about this time in April I added the SR and UV sensors. I was off line before that and I installed WeatherLink 6.0.5. I have the WeatherLink profile set up and can see my data there. But why am I wasting bandwidth on this if the data goes nowhere from WeatherLink?

I thought it might be a quality issue but viewing the Quality Spread Distribution Page, I'm mostly within the range but there are also micro-climates around (canyons and elevation). I don't think its quality.

I'd appreciate a hand if anyone has any ideas.

TIA, J

[dupreezd]

@jerryg, I have a 6163 with UV and Solar since February 2018. It might be time to have them calibrated as well. What was the cost if I may ask?

Thanks

Dries

[JRHill]

@jerryg, I have a 6163 with UV and Solar since February 2018. It might be time to have them calibrated as well. What was the cost if I may ask?

Thanks

Dries

My input? Send the whole outside unit in for R&R. The cost for the UV & SR cal is not cheap but included with the rebuild/test of the whole ISS if I understand the program. I think they charge a bit more for the 'Plus' unit but still, you get the whole thing redone and they did a wonderful job on my ISS a year ago.

[TraderGary]

I might have to rethink my original idea of buying spare UV and Solar sensors.

Now I'm entertaining the idea of buying an entire spare VP2+. That way I should never be without a working system.

[PaulMy]

I've been uploading to WeatherLink for two months now. Everywhere I look I can not find any place what is utilizing my data. There still is not something I'm understanding about the setup. My goals are 1) to have my data be cloud based so there is a history, and 2) a source for neighbors to see the weather real time as the area forecasts are often well off for our canyon.

If you are uploading to weatherlink.com then there are settings to upload to CWOP and WU and from those sites your neighbours can see your data.
Weatherlink.com saves your data history but you need a paid subscription Pro account to view and access that saved data.




Enjoy,
Paul

[JRHill]

I've been uploading to WeatherLink for two months now. Everywhere I look I can not find any place what is utilizing my data. There still is not something I'm understanding about the setup. My goals are 1) to have my data be cloud based so there is a history, and 2) a source for neighbors to see the weather real time as the area forecasts are often well off for our canyon.

If you are uploading to weatherlink.com then there are settings to upload to CWOP and WU and from those sites your neighbours can see your data.
Weatherlink.com saves your data history but you need a paid subscription Pro account to view and access that saved data.

Enjoy,
Paul

Yes, this is true I'm sure. But to date I haven't found any instruction to do so. (WU/CWOP). I've looked and looked but maybe link titles are misleading me.

[PaulMy]

But to date I haven't found any instruction to do so. (WU/CWOP). I've looked and looked but maybe link titles are misleading me.

In your weatherlink.com site select Share & Uploads > Upload > Add Upload > click on the Select a service to upload to > select CWOP or Weather Underground > enter your account information, and interval.

Enjoy,
Paul

[JRHill]

Thanks Mr. Paul. Its all set up!

[jmello65]

Ive still have my Davis Weather Monitor II since about 1992/93 --still working --  bought a vantage -- vantage pro  --  thinking bout doing some upgrades ----  i have uv/solar sensors on other brands -----  question is   is the davis uv/solar sensors really worth getting --- bit expensive

[TraderGary]

Ive still have my Davis Weather Monitor II since about 1992/93 --still working --  bought a vantage -- vantage pro  --  thinking bout doing some upgrades ----  i have uv/solar sensors on other brands -----  question is   is the davis uv/solar sensors really worth getting --- bit expensive

The reason that Davis UV and Solar Sensors are so expensive is that they actually ARE real, professional, calibrated, individual, UV and Solar Sensors. The inexpensive UV/Solar Sensors that you see from other vendors are nothing more than a single cheap light meter that uses an algorithm to only guess what the actual UV and Solar values are.