Posted By: ikimikiThe Davis VP2 seems to be close to $600

N.B. If you want a wireless Davis then you can't buy direct from the US because the US unit uses radio frequencies that are not suitable for use in the UK.

There are several UK suppliers. I can personally recommend ProData (www.weatherstations.co.uk/).

am I right in thinking that it'll cost £600-ish in the UK?

Yes.

Wired "Extras" can however be imported at a considerable saving and plugged into a UK sourced main unit. I have a UK supplied wireless VP2 for wind, rain, temp & humidity. Then I added a solar sensor purchased from Archer Trading in the US at around half the price I might have paid from a UK supplier.

Also note that If you want a Davis VP2 to talk to a computer you must[1] also have one of the various flavours of "WeatherLink". "WeatherLink" is both software and hardware. I don't use the WeatherLink software, but the hardware bit of WeatherLink is essential whatever software you use (basically it sits between the console's connector and some other standard connnection).

PS. Have you come across OWFS (1 wire File System)? That is used by quite a few of the "open" Linux based weather projects.

PPS. Interface details are available for various of the weather stations, which is how come there are so many types of weather software available, but I'm assuming you don't want to get involved at such a low level. I could be wrong.

[1] I think there may now be a third party hardware interface, butI have no experience of it?

skyewright -- may I ask, what are the distinct advantages of the Davis VP2 over the alternatives ?

Is it just a matter of quality and reliability?

Posted By: ikimikiskyewright -- may I ask, what are the distinct advantages of the Davis VP2 over the alternatives ?
Is it just a matter of quality and reliability?

Mainly those. "build" quality as well as sensor quality.
If you held a VP2 sensor in one hand and the equivalent from one of the cheaper models in the other hand, you'd have no doubt as to which 'felt' better!
I started off with an Oregon Scientific WMR200. The anenometer on that "wore out" after about 18 months in our NW Scotland coastal location. I've also worn out an Oregon Scientific WMR928 (better build quality than the WMR200, but no longer available). I have friends who have worn out La Cosse's

The rain bucket on a VP2 is a good big 200mm one, with a resolution of 0.2mm. Many of the others have smaller buckets (typically 100mm) and lower resolutions (typically 1mm).

If you happen to be interested in solar radiation then the VP2 is pretty much the only game in town (there is a one wire sensor. I have one. It's no substitute.).

Oregon do a UV sensor for some of their stations. It is far cheaper than the Davis, but aside from any build quality issues it only has a resolution of 1 rather than 0.1.
UV isn't particularly important to me, so for me an Oregon UV unit has so far proved perfectly adequate.

It depends a bit on your location and what you want to measure. If you are in a mild location a cheaper model may do. If you are not sure how interested you are, then a cheapish station from, say, Maplin (make sure it's one with a PC interface) could be a starting point. If you prove to be are happy with that all well & good. If you decide to move up to a VP2, then you have a second string unit (maybe with the sensors in different places). If you are using suitable software you can continue logging from both sets of sensors (e.g. my 'old' WMR200 & WMR928 'outdoor' temp humidity sensors are no longer 'outdoors' but they are still logging useful temps [the humidity side of both failed ages ago] to Meteohub via the RFXCOM).

For the internal stuff you can use iButtons, they do just temperature ones (thermocrons) or temp and RH (better resolution but more expensive). My CurrentCost Envi also logs temperature as well as up to 9 electrical circuits (the newwer R version can do 10 with one being the Opto so that the unit can be accurately calibrated, I am thinking of getting one of these). There are other way of measuring internal temperatures, Hobo make loggers that are pretty good.
I also have a LabJack, this is a bit more specialised, but has a built in temperature sensor and can take several (can't quite remember how many) inputs and outputs.

Posted By: skyewrightI think I recall someone on the Weather-Watch forum attaching a very small 'educational' PV panel to a LabJack and using it as a solar sensor.

I did that a few years back, you have to put a resistor in parallel with it, works well.

As for the CC reading a degree over, I think mine does as well, but for comparative stuff that is fine for me.
Accuracy can become a red herring sometimes.
Just playing with that thermal mass data and accuracy and precision is going to be a problem there for the two days I had the stuff in the sun, mainly because it was only 2 days and the other test was for 26.

Posted By: skyewrightPossibly unit specific, but the temp reading from my CC Envi is nearly a degree out.

In my limited experience being within one degree counts as a direct hit. I had a CurrentCost, three DS18S20s, the two temperature sensors on my TriStar MPPT PV charge controller (heat sink and battery (though not actually on a battery)) and a mercury-in-glass (photographic) thermometer all on the same bench together. The best you could say was that the offsets between them all seemed pretty consistent if the temperature was stable (response times to changes were different).