VP2 solar sensor

[TokKiwi]

Propanol or Iso-Propyl-alcohol would do as well (sometimes used as whiteboard cleaner) and I think Aardvarks know the stuff... Counting down hmmm, four weeks is it?

Yes, I have fun coming sometime in the future with a solar cell  (no rush Dave - its cloudy wet winter here so I have to wait till at least September before i could get a full solar reading (well they do come but fior 20 mins at a time )

[aardvark]

Davis specifically say Ethanol,    I think it may be some denaturing item added to the isopropanol.   Now denatured alcohol is ethanol with a bit of Methanol to make it toxic.  hmmmm

4 weeks, no, no ..less than that.   Ah   2 weeks for aardvark.. ok..  If you don't count workshops on  the 7,8,9 and 17....  then it is now...


arghhhhhhh

[daveq]

I called Davis today about the height of the diffuser compared to the housing.  Unfortunately I didn't get much info.  I had to wait on hold for a few minutes and when they got to me I was rushed to get off the line. 

I asked about the height of the diffuser and was told that was the way it was designed and that it would read the sun just fine.  Any other questions?  No.  Thanks for calling, good bye.  So I guess that's the way it is. 

Hopefully I'll get the mount completed this weekend.  Won't be putting it on the roof for a few days at least.  Temps are supposed to be in the high 90s with dew points in the upper 70s.  Also too easy to damage asphalt shingles in those temps.

--Dave

[aardvark]

at least you can go up on the roof.. I have metal shingles now, looks great,but the installer said it gets slick quick up there ...   I looked at my solar/uv sensors and it appears that the diffuser is above the housing.. I recall vaguely when I was having issues with the UV sensor reading 0.7 at night with the vp1,  (davis sent new sensors),  I mounted it and the diffuser fit just fine above the housing...

[daveq]

Well the top of the diffuser is just below the top of the housing but there is a step about 1/8" (3mm) below the outside edge.  You can see it in one of pics I posted earlier.  The bottom of the diffuser is even with that step.  Davis has sold thousands of these so I guess the design is sound.

Just finished my mounting shelf.  I made the hole in the shelf just under a 1 1/2" but now that I've got it finished I find the hole could have been about an inch in diameter.  I was assuming that the housing would sit on the shelf but the sensor would have to clear it.  But.... the whole thing floats on the springs so the hole only has to be large enough to clear the compression nut and allow some room for adjustment.

If I were going to make another I'd make the large hole diameter just a little larger than the top of the sensor.  That way you could turn the sensor over, the ears will then sit directly on the mount, and using a centering drill bit you could get the location of the mounting screws very accurately.  This is what I actually did but due to the size of the center hole the screw holes are closer to the edge of the hole than I would like.  May make another tomorrow.

BTW... as someone else asked.  Now what model of Davis do I have?  Not a VP2+ because I don't have a UV sensor.  VP2- VP2\ VP2> ??  I'm leaning toward  VP2* 

--Dave

[Clanger]

Hi Dave,
           Be good if you could post a pic of your mounting shelf. I don't think i will change mine now but you never know. I made the centre hole just big enough for the nut. It still floats on the springs as I found some longer bolts.
Strange that the doc that comes with the solar sensor seems to presume that you will be using their shelf. But the instructions that come with the UV sensor, on the Davis site, have a template and directions for mounting it on your own hand made wooden shelf.
            I to thought it was a little strange that it does not stick up higher but looks like it works fine.

[daveq]

I didn't realize that Davis had a template unfortunately the pdf viewer I'm using doesn't display several of the images and the template happens to be one of them.

Here's what I have.  The shelf is the end cap for plastic guttering.  The metal bracket with the 'V' is something I had lying around; needed something to extend past the lip on the shelf.  The backing plate part of the u-bolt will be inside the shelf which will sandwich the shelf between the two.  Haven't drilled all the holes yet but this should work.

The shelf is fairly thick so I just drilled undersized holes and drove the threaded bolts through them.  I was thinking of epoxying nuts on the underside but the whole thing is very solid and will skip that.

--Dave

[Clanger]

That's a good idea, thanks. I may have a go at making one like that. Unfortunately i didn't take any pictures of mine before it went up  . But here is a screen grab of yesterdays sun  Not sure what happened between 6&7 as i thought we had a perfectly clear day.

[broadstairs]

That's a good idea, thanks. I may have a go at making one like that. Unfortunately i didn't take any pictures of mine before it went up  . But here is a screen grab of yesterdays sun  Not sure what happened between 6&7 as i thought we had a perfectly clear day.

Are you sure that there is nothing which could cast a shadow over the sensor. When I first placed my solar sensor I had not thought that the TV aerial could cast a shadow over it, how wrong I was. My sensor is now above the TV aerial. My problem was that I had not thought about how far N in the NW sky the sun sets either side of mid-summers day.

Stuart

[aardvark]

could have been a cloud

[Weather Display]

notice how the dew point changed during that time
i would say that you had an airmass change, and the change in moisture in the air and or as well pollutants decreased the amount of solar radiation arriving
was there a wind direction change at the same time?

having solar is neat....another whole dimension 

[Clanger]

Thanks for your replies. I didn't post back straight away as i wanted to check if the same thing would happen again.
I did not think it was anything getting in the way mainly because of the curve, it was a  very smooth down ward turn and a very smooth upward curve back. When a cloud goes in front its often a sudden drop.
Brain your suggestion was interresting, i didn't think for one moment that these things were that sensitive. I now have no regrets about getting it, took long enough, so much more information just from one sensor.

But the same thing happened yesterday    so i need to find out what is happening. I,ll try and find out in the next 2 days or so. Its not the easyest place to get to. PLEASE DAVIS MAKE A TRANSMITTER FOR THESES THINGS.
Looks like August will have to go down as a test month 

[Clanger]

Never found out what was causing this. I have taken it down and will move it slightly and give it a clean. Think also i am going to try and make a better support / bracket. One like daveq or nikos see if i can find some perspex.
I will also make a better connection with the cable.  Now have a tube of silicone to fill up the plastic sleeve.
How long does this silicone take to set? It says on the tube tack free in 30 Min's. So do I wait until that time before putting the sleeve back together or just do it up straight away. Thanks.

[daveq]

I put mine up right away.  Just be a little gentle.

I did download the UV installation instructions from Davis but when I printed it out the image was just a slight bit smaller than the actual sensor.  Most likely the fault of the printer.

--Dave

[niko]

IIRC the "template" in the pdf has no dimensions