Topic: Best way to get solar radiation data for computing evapotranspiration and THSW?

[NeverDie]

I hadn't realized until I dug into it deeper that, apparently, the UV data that an Oregon Scientific UVN800 can provide apparently isn't an especially good proxy for a more on-point direct solar radiation measurement.  Also, I hear OS doesn't make an add-on solar radiation measurement device.

So, what are the alternatives?  I've read about the solar-in-a-jar device.  However, rather than start yet another project, I'd prefer something a bit more off-the-shelf that "just works".  

Which other vendors have something wireless for measuring solar radiation that works in the 433Mhz range?
I'm using an RFXCOM to read the wireless data, so I'm somewhat brand indifferent as to which sensor I use as long as it transmits close to the neighborhood of 433Mhz.

Naturally, I am aware Davis has a solar sensor (model 6450).  However, getting an entire Davis setup (as nice as I'm sure it would be) just to get solar radiation data is overkill.  Short of that, would there be an easy way to acquire the data from a 6450?

I'll keep searching, but I'm hoping many others have already blazed the trail and can point the way.

Any suggestions would be welcome.

[aweatherguy]

The 6450 is an analog pyranometer that requires a 3V DC power supply and produces an output voltage linearly proportional to solar radiation levels. If you have some electronics skills, you could use something like an Arduino to read the 6450's output voltage, then add a 433MHz transmitter to send the results. Don't know easy it would be to make something like that have a reasonable battery life -- or you could power it from a small 5-volt wall-wart or the Arduino's USB cable.

AFAIK, none of the less expensive manufacturers make pyranometers. Most pyranometers I've seen advertised are not wireless units -- they are like the Davis unit and require additional electronics to get the data into a computer.

I think you might be looking at a project here. Let us know if you find something wireless.

[NeverDie]

Let us know if you find something wireless.

Other than the Davis (and a few others of comparable or greater price than the Davis), the only less expensive one I may have come across has been the Fine Offset WS3081 (http://fineoffset.com/wh3081.htm).  As indicated in the review, the light sensor has reportedly had problems.  One of the follow-up messages posted in May 2013 is suggestive that the problems might have been  fixed in 2013, but it's a bit ambiguous and I couldn't say for sure.  Also, I'm not even sure whether what it has qualifies as a true pyrometer.

Also, some of the irrigation controller companies (e.g. Hunter) seem to have their own version of a pyrometer as part of an ET package.  The Hunter one offers a wireless link, but it's unclear as to whether it is a closed system.

[wxtech]

This information may help:  http://www.lexingtonwx.com/techdata/Wp53SolarSensor.pdf
I have more information about the circuit and construction.  I'll post that when I find it.
Al