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 comment:

  1. From yedterday:
    Here is the link