Solar Generation History

In previous blog posts I’ve explained about both my Solar Array and my Battery Install.

In these two articles I detail the specifications about the installs; size, direction of panels, photos etc.

Recently I’d been asked how much solar do I generate and how does the recent addition of battery and our EV impact the export numbers, so here you go.

As detailed in the Solar post, my system was installed in September 2019. But it took me a month or so to get my monitoring system all up and running. So the first full month data I have is November 2019 onwards.

I create all these stats and figures by using the data from my Open Energy Monitoring emonPi system. This CT clamp based is constantly monitoring the ins and out of my solar setup (and import/export, to/from battery and even EV).

Any device you attach a CT clamp to can be monitored individually.

You can read all about their open source hardware and software here: https://guide.openenergymonitor.org/applications/solar-pv/

If you’re into system stats I can’t recommend the emonPi system highly enough. It’s absolutely top notch.

I am also a big fan of the PVOutput platform: https://pvoutput.org/

Where you can create text based lists like the following. This shows my top 20 days of generation.

Now you shouldn’t plan your solar install and usage patterns around days like these, because they are rare. But these days are definitely when you want a hot water cylinder, battery or EV to put all the excess.


Installation Timeline

Here’s a quick summary of our hardware installation timeline.

  • Sep 2018 – 5.1kWh of Solar Installed on a 3.68kWh Solaredge inverter
  • Feb 2020 – Installed 4.8kWh Lux and Pylontech battery system (2 batteries)
  • Aug 2020 – Took delivery of EV and installed Myenergi Zappi Charger
  • Oct 2020 – Installed a third battery taking total capacity to 7.2kWh
  • Feb 2021 – Installed a further two batteries taking total capacity to 12kWh

Lots of tables and stats

Here’s a short description of the columns shown in the tables below. Note, all figures are kWh unless otherwise stated.

  • Gen – the total amount of solar generated (in kWh) for the whole month
  • Avg Gen – the amount generated divided by number of days in month to give a daily average

  • Cons – the total amount of electricity consumed within the home for the whole month (regardless whether from generation or solar)
  • Avg Cons – the total amount consumed divided by number of days in month to give a daily average

  • Import – the total amount imported from the grid for the whole month
  • Avg Import – the amount imported divided by number of days in month to give a daily average

  • Export – the total amount exported back to the grid for the whole month
  • Avg Export – the amount exported divided by number of days in month to give a daily average

  • Export % of Gen – the amount exported compared to generated shown as a percentage

Monthly Stats 2018

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
Nov-20181103.72939.82428.1592.054%
Dec-2018892.933110.72809.0381.243%

Monthly Stats 2019

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
Jan-20191193.831410.12558.2601.950%
Feb-20192549.129210.41906.81525.460%
Mar-201939812.833110.71876.02538.264%
Apr-201949416.52879.61264.233211.167%
May-201954517.62688.61123.639012.672%
Jun-201947615.92558.51083.633011.069%
Jul-201956018.12538.21103.541713.574%
Aug-201956218.12548.21073.541513.474%
Sep-201941113.72598.61394.62909.771%
Oct-20192467.92377.61595.11685.468%
Nov-2019832.831510.52668.9341.141%
Dec-2019963.134111.02859.2401.342%
Total424434062044288168%

First full year of the system generating 4244kWh through the year. I was delighted with that.

This was before batteries and the EV, so you can see that I exported a whopping 68% of what we generated, so only 32% used in the house? Grrrrr!!

Even in darkest December 50% of what I generated went back to the grid.


Monthly Stats 2020

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
Jan-20201143.731210.12548.2561.849%
Feb-20202057.332611.62187.8963.447%
Mar-202041113.338512.41113.61364.433%
Apr-202058619.538812.9782.62769.247%
May-202069422.440213.0371.232910.647%
Jun-202051417.140513.51364.52458.248%
Jul-202051516.641813.5672.21645.332%
Aug-202046815.145914.81133.61213.926%
Sep-202043214.448016.01264.2782.618%
Oct-20201866.059619.241913.590.35%
Nov-20201204.050716.938913.020.12%
Dec-2020792.562020.054617.650.26%
Total432452982494151735%

The second full year shows we generated another healthy 4324kWh, but we only exported 35% of it back to the grid.

So 65% used in the house because of the batteries and EV coming into play throughout the year.

But despite onsite usage going up, so did energy imported. This will be charging the EV at off peak times.

You can see this in the jump in consumption figures too.

Look at December this time around, just 5kWh sent back to the grid. That’s better!!


Monthly Stats 2021

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
Jan-2021953.159719.350416.320.12%
Feb-20211906.847617.029410.580.34%
Mar-202134911.356618.32708.7531.715%
Apr-202157119.049916.6411.41143.820%
May-202150016.159619.21705.5732.415%
Jun-202158519.555018.31003.31354.523%
Jul-202156818.361019.71143.7722.313%
Aug-202143213.950016.11063.4371.29%

Only part way through 2021 so far but you can see the impact the increased battery capacity and continued use of the EV have had on export figures.


Generation Summary through the months and years


January Comparison

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
Jan-20191193.831410.12558.2601.950%
Jan-20201143.731210.12548.2561.849%
Jan-2021953.159719.350416.320.12%

February Comparison

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
Feb-20192549.129210.41906.81525.460%
Feb-20202057.332611.62187.8963.447%
Feb-20211906.847617.029410.580.34%

March Comparison

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
Mar-201939812.833110.71876.02538.264%
Mar-202041113.338512.41113.61364.433%
Mar-202134911.356618.32708.7531.715%

April Comparison

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
Apr-201949416.52879.61264.233211.167%
Apr-202058619.538812.9782.62769.247%
Apr-202157119.049916.6411.41143.820%

May Comparison

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
May-201954517.62688.61123.639012.672%
May-202069422.440213.0371.232910.647%
May-202150016.159619.21705.5732.415%

June Comparison

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
Jun-201947615.92558.51083.633011.069%
Jun-202051417.140513.51364.52458.248%
Jun-202158519.555018.31003.31354.523%

July Comparison

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
Jul-201956018.12538.21103.541713.574%
Jul-202051516.641813.5672.21645.332%
Jul-202156818.361019.71143.7722.313%

August Comparison

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
Aug-201956218.12548.21073.541513.474%
Aug-202046815.145914.81133.61213.926%
Aug-202143213.950016.11063.4371.29%

September Comparison

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
Sep-201941113.72598.61394.62909.771%
Sep-202043214.448016.01264.2782.618%

October Comparison

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
Oct-20192467.92377.61595.11685.468%
Oct-20201866.059619.241913.590.35%

November Comparison

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
Nov-20181103.72939.82428.1592.054%
Nov-2019832.831510.52668.9341.141%
Nov-20201204.050716.938913.020.12%

December Comparison

Month & YearGenAvg GenConsAvg ConsImportAvg ImportExportAvg ExportExport % of Gen
Dec-2018892.933110.72809.0381.243%
Dec-2019963.134111.02859.2401.342%
Dec-2020792.562020.054617.650.26%

Summary

My Solar PV system is brilliant, I absolutely love it. I’m actively investigating if I can someone extend the system too.

But it was very tough through that first full year seeing oodles of generation go back to the grid.

Adding the batteries and then getting the EV has totally changed the way I view my solar now. In fact, I love it even more now.

For most of the summer I barely import more than a few kWh per day.

Each kWh generated in 2021 is saving me much more money than it did in 2020 because of the recent increases in import costs.

During the winter the batteries come into their own when we can load then up with off peak energy.

There are still times through the summer when I can have filled the batteries by lunchtime and if the EV is away from the house being driven we can be exporting back to the grid like billy oh all afternoon!

A water cylinder (and PV diverter) is the next obvious choice to make use of this spare generation.

So we still have some electrification to do in the house over the next few years too:

  • Install a Water Cylinder (stop using Combi boiler for direct hot water)
  • Induction and Electric Cooker (our gas cooker is showing its age)
  • Heat Pump (to fully replace the old Combi)

So the solar and battery setup should continue to pay dividends for many years to come.


Thinking of Solar? Where you gonna dump the excess?

If you’re thinking about owning solar then I’d suggest that you also have to consider where you are going to dump the excess.

No matter how hard you try to do the washing and cooking when the sun is shining you will not be able to use all electricity you generate, especially from March to October.

Yes, you could try and make some money by exporting via Octopus Energy Outgoing, especially the Agile version when energy prices are high.

But for an easy life and use the energy within your house (and not pay import costs) you’d need somewhere to divert your spare generation.

The more of your generation you can use in the house the better your return in investment (ROI) will be.

So where could you dump that excess?

Water Cylinder

Probably the best bang for your buck. At less than £400 a Myenergi Eddi PV diverter will dump any excess generation to the immersion in your hot water cylinder. This will likely pay for itself pretty quickly.

As well as a conventional water cylinder you could divert to a smart cylinder (like a Mixergy) or a Sunamp heat battery.

EV Charger

Very similar to the Eddi, the Myenergi Zappi EV charger will divert excess generation to your car.

The beauty of the Eddi is that it can put very small amounts of excess generation into the water cylinder, just a few 100W.

Whereas your EV needs 1.4kWh available to fire up the charging mechanism of the EV. This probably won’t be an issue on sunny days.

But don’t let that put you off as you can also part top up the Zappi with Grid (or battery) to get to the 1.4kWh minimum that your EV needs to fire up the charging mechanism (ie a mix of 900W Solar and 600W from grid or batteries for example).

Home Batteries

As detailed in my home battery blog post, batteries can be used two ways. Both for dumping excess PV into and also charging at off peak times for use later.

As you can see from the figures and stats above, the batteries have been a game changer for us.

Other options?

Bottom line is that any electrical device in your house could be used for dumping spare generation. But the ones listed above are the easiest and are sort of ‘fire and forget’ options that don’t need a great deal of user interaction.


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