2023 Review in Numbers

2023 Review in Numbers

In this post, 2023 Review in Numbers, we will look at the all facts and figures behind my renewables for the whole of 2023.

Summarising how the solar and heat pump performed as well as some of the financial benefits and calculations.

System Overview

A quick reminder of what equipment I have in play:

• 5.1kW of solar panels on a 3.68kW Solaredge Inverter
• Lux AC 3600 inverter connected to 5 x 3.2kWh (16kWh total) of Hanchu batteries
• 5kW Vaillant Arotherm air source heat pump
• 250L Mixergy water cylinder in a custom built plant room
• Myenergi Eddi solar diverter
• Myenergi Zappi EV charger (and solar diverter)
• Octopus time of use tariffs (Go and Intelligent Go used in 2023)
• Investment in Ripple Windfarm

Most of these items have their own blog entry.

Blog Summary

And the house is a regular 3 bedroom, 3 storey (loft conversion) 1930’s semi detached. 98sqm of floor space, EPC D rating at last inspection.

Solar Performance

You can find more detailed monthly and yearly breakdowns of my solar performance going back to late 2018 in the following post.

My Solar Generation History

From that page we’ll pull out the month by month stats for 2023.

As well as how 2023 compared to previous full years.

As you can see, total solar generation was down in 2023 versus previous years.

If I dig into the monthly stats I can see that March, April and July were the main culprits.  March being over 100 kWh down on previous 4 year average for example.

But the system still produced over 4,000 kWh, with the grand total now being over 21,000 kWh across the 5 full years.

ASHP Performance

In a similar vein to the solar performance stats I’ve been keeping monthly records for my 5kW Vaillant Air Source Heat pump.

You can find all the breakdown here:

Heat Pump Performance History

As 2023 was my first full calendar year with the heat pump I only have a single year of data to this point.

So we achieved a full year SCOP of 3.75 for both heating and hot water.

Happy enough?  Well sort of.  But I know 2024 is going to be much better.  You can see the hints of this in December 2023 where I achieved a COP of 4.12

How this was all achieved will all come in my “second winter with my ASHP” article which I should post sometime around the end of the April 2024.

But without giving too much away; fully open system using weather compensation, no 3rd party controls, no zoning or closing rads off and enabling more efficient hot water production.

You can find lots of information about last winter (2022/2023) in this article.

First winter with my air source heat pump

You can also find minute by minute stats of my running heat pump here:

https://emoncms.org/energystatsuk

Electricity Breakdown

• Complete year consumption: 10,297 kWh

This has topped 10,000 kWh for two years now.  It was 3412 kWh (9.3 kWh per day in 2019) before I embarked on migrating to electric.

• Solar Generation: 4,065 kWh
• Exported Surplus: 310 kWh (7.6% of generated)

10,297 kWh consumed minus 4,065 kWh solar = 6,538 kWh

• Electricity Imported: 6,538 kWh

Because of the solar we were able to drastically reduce the amount of electricity that we had to buy from the grid.

• To EV: 1,006 kWh (10% of consumption)

This is lower than previous years as the car was in the garage for a while and the loan car was a petrol.

• To Eddi: 570kWh (6% of consumption)

In spring/summer 2023 I continued to divert surplus solar PV to the Mixergy water cylinder using the Myenergi Eddi diverter.

Towards the end of the summer I gave up on this and just used the ASHP for hot water to make use of the warmer outside temperatures to get good COP on hot water runs.

I don’t think I will be using the Eddi in 2024.  I will consider 15p exports instead and use the ASHP for hot water.

• To Battery: 4,494 kWh

This is posted just to show how much use the batteries got across the year, from both direct grid charging and surplus solar.

Round trip efficiencies show around 82% (in versus out), but I did add an extra battery in the middle of the year, so not sure if that skewed anything?

One to keep and eye on.

• To Mixergy Immersion: 451 kWh (4.5% of consumption)

This was more experimenting.

I was using the ASHP to take the hot water to around 50C overnight and then using the immersion within the Mixergy to take the tank the rest of the way to 65C.  Giving way more usable hot water.

COP really drops off once you get past 50C using the heat pump.  And with the overnight rate on Go (and now Intelligent) only being around 8p per unit, it didn’t quite matter as much that the immersion was only 100% efficient (COP of 1).

If you are desperate to leave yourself with a good COP but you still want lots of hot water, this could be a worthwhile strategy.

• To ASHP: 2,856kWh (28% of consumption)

As per the ASHP section above, more than a quarter of my electricity needs went to the heat pump this year.

• Everything else: 4,935 kWh (13.5 kWh day) (48% of consumption)

I’ve got a NAS box, two little microserver, lad has his Xbox (that seems to be never off), we have an old Plasma TV, a couple of POE Wi-Fi access points and some POE surveillance cameras.  It all add ups.

We are a house of 4 with two teenagers, so we are constantly washing and drying.

Also, working from home is now a thing, so we do spend more time at home in the week than previously working on the computer etc.

My overnight baseload is around 260 watts, which in itself is 6.25 kWh per day.

Back in 2018 my overnight baseload was around 100 watts less.  So lots of new kit added (and about 3 kWh per day to go with it!).

I might have to hunt all that extra stuff down and looking to reduce, LOL.

Financial Breakdown

In this section I’m going to try and show in financial terms how the various renewables and things like time of use tariffs helped.

I’m going to use 29p per unit as the price for electricity comparison as that is what I’ve been paying off peak on Go / Intelligent tariff as well as this being the price point on a standard tariff / price cap.

• Total Electricity Consumed: 10,297 kWh (£2,986 if all bought at 29p)

As we generated over 4,000 kWh of solar we only needed to buy 6,538 kWh of electricity.

• Total Electricity Imported: 6,538 kWh (£1,896 if all bought at 29p)

As we make heavy use of Time of Use tariffs (Octopus Go and Intelligent) our average import cost across the whole of 2023 was 12.5p per unit.

• Total Electricity Imported: 6,538 kWh (£817 when bought at 12.5p)

As I’m on old Feed In Tariff (FIT) terms for my solar, I get paid for what I generate and what I export.  In 2023 this totalled £346.

• Total cost after taking away FIT payments: £817 – £346 = £471

And finally I have a small investment in the first Ripple energy windfarm which provided a saving of £75 in 2023.

• Total cost after taking away Ripple benefit: £471 – £75 = £396

So from an initial theoretical bill of almost £3,000, the renewable investments and time of use tariffs bring that down to just £400 for the year.

I’m really happy with that.

Yes, I appreciate that solar, batteries, EV all require financial investment and the return on those investments will take many years.

But the savings are there if you are fortunate enough to be able to make that investment.

Note: regardless of how you get your electricity you will need to pay the daily standing charge.  This would have totalled around £185 as it’s currently 50p per day for electricity.

One further point on the ASHP.

• That used 2,856 kWh x 12.5p = £357 to run for the year (excluding solar contribution).
• Which would have been 2,856 kWh x 29p = £828 at standard rates.

I wrote an article where I try to help demystify the relationship between heat pump COP/SCOP and the amount you would pay for your heating and hot water.

Peak / Off-Peak Breakdown

Using the reports feature of Octopus Watch I am able to see the average usage breakdown across the whole of 2023 as well as a percentage split of peak and off peak usage.

The report also tells me (amongst a whole host of other things) how imports are broken down.

• Peak Imports: 25%
• Off-Peak Imports: 75%

By scheduling big tickets items overnight like hot water runs, charging the EV and filling the batteries I am able to make a significant reduction in average unit price paid.  Just 12.5p across the whole of 2023.

Gas Usage

As mentioned earlier in the post, the only gas device we have left is the 60cm wide gas cooker and hob.

My goal for 2024 is to replace this with an induction model and then get the gas meter capped off.

• Total Gas Used: 641 kWh
• Gas Cost: £55
• Standing Charges: £96
• Total Cost: £151

So almost 64% of my gas bill was standing charges.  By moving to the induction hob and getting the gas meter capped off I can save almost £100 in gas standing charges.

That will be a good day!

Credits and Mentions

I was able to pull this report together because of the amazing apps and tech that is out there.  I’m going to mention what I used below.

• Open Energy Monitor (https://openenergymonitor.org/)

I’ve been using their solar and electrical monitoring package for over 5 years now and it has been flawless.  This is how I get the breakdown of EV, Eddi, Mixergy usage etc as I’ve got CT clamps around all these devices.

Then just when you think they couldn’t surpass themselves they create their heat pump monitoring package and https://heatpumpmonitor.org/

I’m on there every day, It is truly amazing.

• Octopus Watch by Smarthound  (https://octopus.smarthound.uk/)

This is my go to app for Octopus Energy tariff pricing.  It not only does pricing but it creates some amazing reports like the one I’ve shown above.