Just to add this,
http://www.clearskycalculator.com
Is a very useful tool to check the solar radiation output from any solar sensor. On a clear, pollution free day (which I am sure you get plenty of in Picton) your sensor should read no more than the figure the calculator calculates on any given day of the year, latitude etc. and an offset applied to the readout if it does.
http://www.clearskycalculator.com
Is a very useful tool to check the solar radiation output from any solar sensor. On a clear, pollution free day (which I am sure you get plenty of in Picton) your sensor should read no more than the figure the calculator calculates on any given day of the year, latitude etc. and an offset applied to the readout if it does.

