Thursday, 7 September 2017

Confidence Trick

Regulars will remember I had a plan for identifying the probability of good weather on each day of the year by charting the average solar energy production of our Solar PV system over the last 4 years.

The issue was that using the average wouldn't necessary show the level of confidence as there could be a wide disparity in the readings. So what I did was to include a column showing the standard deviation. However, the SD works counter-intuitively, in that a low number equates with high confidence and a high number a low confidence. To overcome this I divided the SD into 1 and plotted this figure, which shows a more intuitive value for confidence.

You have to click on the image to see it in any detail, but the red line is the average solar generation over 4 years for each day of the year and the blue is the level of confidence in that average - anything in excess of 0.5 (on the right hand scale) is a high confidence. As can be seen from the chart, confidence, whether that be of sunny or dull weather, is highest at the start and end of the year. I suppose that's to be expected in cooler weather, when the air is more stable.

5th of August has a high confidence, here at least, of being a crap day.


  1. From yedterday:
    Here is the link

    1. while the link shows all evidence of the offer still being valid, there's nowhere to actually subscribe, which makes me suspect it's finished.

    2. Found it eventually - it was to do with the link you provided be for a mobile, as opposed to a laptop.