|daily power generation by month|
|violin plot of daily power generation, showing notched box plots of mean (dot), median, quartiles, and outliers, overlaid on a density plot|
You can clearly see the effect of the year: much more in summer than winter. Interestingly, December, containing the winter solstice, was better than November, which, as usual, was a miserable month; December has some lovely sunny days.
No sun – no moon!
No morn – no noon –
No dawn – no dusk – no proper time of day.
No warmth, no cheerfulness, no healthful ease,
No comfortable feel in any member –
No shade, no shine, no butterflies, no bees,
No fruits, no flowers, no leaves, no birds!
— Thomas Hood, 1844
We can look at the energy generation across each day for the whole year, and can clearly see the changing sunrise and sunset times, and the darkness near the end of November.
|Each pixel represents the energy generation at the sample point, one every 5 minutes. Time is in GMT throughout. The colour indicates the energy generation in the relevant interval: darker colours indicate more energy.|
It’s even easier to see the effect of the seasons looking at the generation through the day. The curve gets higher and much broader.
Of that power generated, we use some, and export the rest to the grid. In March we got an extra device to measure this, too. (March was anomalous in that our hot water boiler was out of action for about a week, so we were using more electricity than usual.)
The situation is actually even greener than this implies: some of the orange usage of generated power is being used to heat our water, thereby saving gas consumption, too. That is why there is such a large oragnge lump in December: nearly all excess power is heating the water for the central heating. In the summer, the only water heating is for hot water, as the central heating is off.
Next year we’ll have data to compare across years, not just months. I’ll need to write more Python scripts for that. Great fun!