solar power generation stats

Graphs of the electricity generation statistics gathered from our solar PV generation system.

Power generation: annual summary

Our annual power generation in MWh (bars), with shading indicating the contribution of the respective months. (Generation started on 9 Jan 2014.)

Power generation: daily total and running averages

Our daily power generation in kWh (bars), along with minimum (dot-dashed), lower quartile (dashed), median (solid), upper quartile (dashed), maximum (dot-dashed) running averages over the previous 14 day sliding window.

On 29 April 2016 a quarter of the panels stopped generating. On 7 May 2016, a further quarter of the panels were taken offline for a short while around 11am, to help diagnose the fault. On 16 May the whole array was switched off for a short while, while panels were diagnosed and reconfigured; it was switched back on with all but one panel working. On 2 June 2016 the failed panel was replaced.

Power generation: daily generation by month

Our daily power generation in kWh, per month, using a jitter plot (some jitter is applied to the horizontal position, to prevent overlapping).

Our daily power generation in kWh, per month, using violin plots (a notched box and whisker plot—where the box shows the inter-quartile range, with 95% confidence interval notches; whiskers show data within 1.5*IQR—plus a kernel density plot). The final, partial, month tends to have larger notches, because it has less data.

Energy generation: daily stats (1)

The vertical time axis runs from 3:00am to 9:00pm GMT. There is one column of data per day. Data is gathered every 5 minutes.

Energy generation: instantaneous daily stats

Each pixel represents the energy generation at the sample point. The colour indicates the energy generation in the relevant interval: darker colours indicate more energy.

Energy generation: daily stats (2)

Data is gathered at 5 minute intervals. The horizontal time axis runs from 3:00am to 9:00pm GMT. The vertical axis runs from zero to 8kW. The orange regions indicate the minimum, lower quartile, median, upper quartile, and maximum generation at that time, over the month. The line indicates the actual generation at that time (or the monthly mean, for the monthly average plots). The number in the top right is the total generation in kWh that day (or the monthly mean, for the monthly average plots).

Monthly averages




September 2017

August 2017

July 2017

June 2017

May 2017

April 2017

March 2017

February 2017

January 2017

Half the panels were not generating on 7 Jan, and for the morning of 8 Jan (until the sun came out).

December 2016

November 2016

October 2016

September 2016

August 2016

July 2016

June 2016

The failed solar panel was replaced on 2 June, and the system returned to 100% capacity.

May 2016

A quarter of the panels were not generating from the start of the month. On 7 May 2016, a further quarter of the panels were taken offline for a short while around 11am, to help diagnose the fault. On 16 May the whole array was switched off for a short while, while panels were diagnosed and reconfigured; it was switched back on with all but one panel working.

April 2016

On 29 April 2016 a quarter of the panels stopped generating.

March 2016

February 2016

January 2016

The solar PV was switched off for several hours on the 15th, and a short while on the 28th, to investigate some issues. This was unfortunate, since they were both lovely sunny days!

December 2015

November 2015

October 2015

September 2015

Energy use and export: annual summary

Our annual power imported (red), generated and used (orange), and generated and exported (green), in MWh (bars), with shading indicating the contribution of the respective months. (Data collection started on 8 March 2014; 2014 Jan and Feb contributions have been estimated as the 2015 values, to aid comparison.)

Energy use and export: daily totals

Our daily power used and export, in kWh. The region above the axis represents our usage: blue is “surplus” generated power used by the immersion heater (data on this started being collected from 1 Jan 2015); orange is the remaining ordinary generated usage (or the total generated usage in 2014); red is the extra imported from the grid. The green region below the line is surplus generation exported to the grid.

There are three days of immersion data missing in early April 2015: the (lighter) orange here represents the total generated usage. There is a week of usage data missing in May 2015: the blue is the immersion heater usage, so total generation was at least this.

Energy use and export: daily use and export by month

Our daily power used and export, in kWh, by month, using a jitter plot (some jitter is applied to the horizontal position, to prevent overlapping).

The region above the axis represents our usage: orange is generated usage, red is the extra imported from the grid. The green region below the line is surplus generation exported to the grid.

Our daily power used and export, in kWh, by month, using violin plots (a notched box and whisker plot—where the box shows the inter-quartile range, with 95% confidence interval notches; whiskers show data within 1.5*IQR—plus a kernel density plot). The final, partial, month tends to have larger notches, because it has less data.

Energy use and export: daily stats

Data is gathered at half minute intervals from the Wattson meter. The horizontal time axis runs from midnight to midnight GMT/BST. The vertical axis runs from -8kW to 8kW. The region above the axis represents our usage: orange is generated usage, red is imported from the grid. The green region below the line is surplus generation exported to the grid. Numbers are in kWh; #orange + #green = the total generated. This is slightly different from the other power generation totals, since it is being recorded by a separate, and less accurate, meter.

On the daily plots, you can see specific usage. The big early morning generated usage is from the immersion heater. The early evening spike at the weekends is dinner being cooked in the electric oven; during the week we usually use the gas hob.

On “green date” days, the green area is greater than the red area (#green > #red), meaning we export more than we import, so are nett generators. The rest are days where we import more than we export, taking more from the grid than giving back. On “orange date” days, we still generate more than we import, but use enough of it that we are not nett exporters. On “red date” days we import more than we generate; but even so, may still export a little during the day.

The situation is actually greener than this implies: some of that orange usage of generated power is being used to heat our water, thereby saving gas consumption, too. From 1 Nov 2015 we started collecting data on how much power is being sent to the immersion heater during the day: this is shown as blue on the plots. So after 1 Nov 2015, orange represents generated usage in all but the immersion heater.

Monthly averages




September 2017

August 2017

July 2017

June 2017

May 2017

April 2017

March 2017

Febuary 2017

January 2017

December 2016

November 2016

October 2016

September 2016

August 2016

July 2016

June 2016

May 2016

April 2016

March 2016

February 2016

January 2016

December 2015

November 2015

October 2015

September 2015




Previous years data