Sunshine recorder

[apenwith]

Hi
Cumulus has a facility to import solar data - does anyone know of a reasonably priced sunshine recorder or a DIY project to make one.
Regards

[Gina]

That's something I've wondered too. It would be a nice addition

[steve]

I don't know how you would get a sunshine recorder to work with Cumulus. I don't know what the import facility is.

Steve

[skyewright]

I don't know how you would get a sunshine recorder to work with Cumulus.

'Temp in a jar' (i.e. a temp sensor placed in a small glass jar in an open position) can be a quite effective solar tool, especially if it is just a matter of sunshine hours.
The software would need to be able to calculate the difference between the jar temp and a standard temp (e.g. the main outdoor temp sensor). That difference can then be turned into a percentage using a user defined "difference for 100%", and sunshine hours counted as time when the %age is above some user defined level.

The user would need to tweak the "difference for 100%" occasionally through the year (greater in summer than in winter); though I have wondered if a software controlled "biggest difference in the last, say, 2 weeks" might be a neat way of automating that?

[apenwith]

Hi
There was a device (I forget who invented it) that consisted of a spherical glass flask silvered on the inside mounted above a tube aligned to the pole star. In the tube was some sort of light sensitive thingy. Presumably when the sun shone a bright spot would be refected down the tube. So I wondered about a silver Christmas bauble and maybe a light sensitive diode or photocell. Are there any electronics wizards out there ? Feasible ??
Regards
Alan

[broadstairs]

First you need to decide what you are trying to measure, there are two methods of measuring the output of the sun in w/m² (watts/sq metre). Either direct radiation which requires a motorised detector which tracks the sun across the sky as the day progresses or total global radiation which measure direct and reflected radiation and which is what a Davis VP type solar sensor measures. Using the temp in a jar method is a very approximate method of the latter.

Next if you want to calculate sunshine hours you need a method of comparing the readings with an expected level and deciding upon what % of the expected is 'sunny' and therefore add up the total minutes which are 'sunny'. I know that Davis use a value of 100w/m² to represent sunny conditions but I just dont get how that works since global radiation can very between 0 at night and 900+ w/m² at high summer with full sun.

Even with a Davis sensor comparing to a Campbell Stokes sunshine recorder (the classic 'standard') its not very accurate....

Stuart