Saturday 11 November 2023

Greta Gets Diverted

As many of you will know,  we have done quite a lot to our house over the past 3 years in order to increase it's energy efficiency, it's eco credentials and most recently it's size with the addition of a new room / extension complete with underfloor heating (my heat pump was already sized for this when we bought it) and the house is now toasty and warm.

So, we now have heat pump heating,  solar panels, solar batteries, improved insulation, so what's next? Well my latest foray has been solar diversion.  What, I hear you say, you want to divert the sun ?  Not really,  what I am talking about here is that, like many of you, we have solar panels.  We generate electricity for the house and any surplus you then sell (well the rate is so poor, you almost give) it to the grid.  The concept of diversion,  is to find mechanisms to self consume as much as possible,  reducing costs in the process and generally avoiding the cheap rates being paid back to you.  

I thought this was a relatively new concept,  however, may I first introduce you to Solar Diverter 1.0. It's over 50 years old, maybe older than solar panels themselves and is in the form of my wife,  or, the Rebel.  I tell you,  when she's around, everything electrical gets used.  If she is home,  she totally destroys any opportunity for other diversion technologies to be used.  She max’s out the solar panels and the grid.

Solar Diverter 1.0

In fact,  when she is home,  I feel that the electricity board has to be a little like the US Electricity Board in Lampoons Christmas Vacation.  All of the wind, solar, nuclear and gas energy generation is likely to be ramped up.

But enough,  what have I really done to our house to reduce electricity being exported to the grid.

Battery Storage - GivEnergy

The first real solar diversion tech we got when we first started our eco journey was a battery.  We then extended it by getting a second battery earlier this year.  We have almost 18 kWh of Electricity storage in terms of batteries.  They get charged by the solar (and in winter we charge them up overnight when electricity is only 7.5p / kWh) and then use it if the solar isn't generated during the day.

When the sun shines,  the house uses the electricity any excess is then stored in the batteries, which power the house overnight,  or when the weather is particularly poor.  We also have an Emergency Power Supply (EPS) which will kick in and run from batteries in the event of a power cut.  Once the batteries are charged we hand over to the next step in the chain.

EDDI - By MyEnergi

So when batteries are fully charged,  EDDI gets to intervene.  Having a heat pump is great,  it's really efficient and saves us a lot in heating and hot water costs.  However,  the heat pump still has a hot water cylinder.  The cylinder also has an immersion heater to get the water to over 60 degrees once a week to prevent salmonella. 

So what EDDI does, is divert any excess electricity into the water tank and heat our hot water.  It's taking away any need for the heat pump to kick in and do it.  It means for maybe 9 months of the year, most of our hot water is heated for free.
MYENERGI Zappi Eco-Smart 2.1 EV Charger 7KW WIFI/Ethernet Tamperproof Tethered (White)

ZAPPI - By MyEnergi

In the same way as EDDI, Zappi also diverts electricity.  But this time,  it charges up the car.  Yes that's right,  we have two electric powered cars now and what we are able to do is place any excess energy into the car.  

There is nothing like feeling so smug, driving somewhere, on free electricity.  Being part of the MyEnergi product set,  these two devices are able to work together to maximise our savings.

Electric cars, generally can't be charged on AC electricity under around 1.4 kWh.  So when our excess is lower, say in the morning, or early evening, Eddi kicks in and heats the water.  Once our excess exceeds 1.4kwh,  Eddi stops and Zappi kicks in and charges the car for free.  It also charges the car overnight when the batteries for the house are being charged and we get our cheap rate. 

HARVI - By MyEnergi

This little device is not a diverter itself,  it allows the connection of up to 3 CT clamps, that are placed on the electric cables (e.g. the cable coming into our electricity meter).  By metering the electricity at various points in the supply, it allows the MyEnergi eco system to make the best decisions on what to do at any point in time.  

In fact the products from GivEnergy and Myenergi work seamlessly together. I can recommend both. 

So what's next ?

Not sure yet,  I am thinking of getting a hot tub and good old Eddi can be configured to put free electric into heating that too.  So that may be next.  But just remember,  if in doubt and not sure your maximising your electric usage.  Give me a shout,  I can loan out the Rebel to get you started on your diverter journey (and give our a home a break so that there is some free electricity available to be diverted).

But one thing is for sure,  this has all had a real positive impact on our finances.  Before we started this journey in 2021,  we were paying 7.5p / kWh for Electricity, 2p / kWh for Gas and around £400 per month in fuel for both our cars.  

We're now purchasing electricity at 7.5p / kwh for 6 hours overnight and 29p / kwh for electricity.  So I hear you say, you must be losing out.  Well,  I am now paying £150 per month to run the house and both cars (and I hope to reduce that further when our share in the wind farm comes on-line in March).  That's a saving of nearly £450 per month.  

Sunday 16 July 2023

Greta Goes to Sea

So early in June this year, Octopus Energy stated that, for a small number of lucky customers, they would arrange a trip to one of the UK's offshore wind farms.  You had a deadline of 2nd July to submit a short description of why you wanted to go.  They only planned to run between 4 or 5 trips each with 8-10 customers. In actual fact they ran a small number of additional trips with investors as well.  On the request you had to state why you wanted to go and if you were a lucky winner you would be selected to take the trip.  So I sent them the 200 word statement, referencing my 'You can call me Greta' blog.

On the 11th July, I received a quick telephone call from Octopus, asking me if I would be free to board HMS Octopus the following day.  They invited the Rebel too, but she said she needed to wash her hair that day and how she would be so pleased to have the house to herself if I was to go alone.   I have to say,  my inner Greta came stirring up from deep inside and I couldn't wait to say "I'll be there!". 20 minutes later, with the feeling of great elation (you would think I had won the lottery), I received my email with instructions.

I left early the next morning, saying good bye to the Rebel as she stirred in bed.  I told her I wouldn't be late and she replied "No need to rush back" with a slight tone in her voice and a big sigh of relief.

I arrived just after 8:00 am at their main control centre at Grimsby docks. Here we took part in the safety briefing (the first thing they asked for was the completion of a Next of Kin form),  we were issued with our rather nice and trendy pink high viz jacket and automatic inflating life vest. 

I got a little worried about the life jacket as on contact with water, it will automatically inflate.  So I was rather careful with my drinks that day as well as visits to the toilet.  I was wondering how much water was needed for a premature inflation.

Renata from the Octopus team welcomed us and the whole team made all seven of us on the tour extremely comfortable,  answered our repeated questions and provided some really useful information. It was instantly obvious how passionate they were to be working in the industry and how happy they were to share their experiences. 

We then boarded the boat for hour 1.5 hour steam out to the Lincs Off-Shore Wind Farm and were given some really interesting statistics.  Here's a quick summary of some of the information for the site we visited.

  • The UK is the second largest user of wind power, only China is bigger.
  • It takes approximately 9 years from initial inception, to getting planning approval to final commissioning of a wind farm.  Lincs started the process in 2004 and came on-line in 2013,  with only the last 2 years being the actual construction.
  • Lincs has 75 3.6 MWh turbines
  • Each Turbine is 150m tall
  • The farm is the size of 5,000 football pitches
  • 1 turn of the blades is enough to power 15,000 homes
  • The site generates 270MWh
  • Enough electricity is produced to power 240,000 homes / year.
  • Rotor Diameter is 120m (each blade is almost 60m long)
  • The turbine starts producing electricity when the wind speed reaches 4 m/s (around 8.5 mph) and is generating its full capacity (3.6 MWh) slightly after that and continues to generate the same amount of power up to 33 m/s (approx 75 mph). Above that, the turbine 'feathers' itself to protect itself in storms. 
More interestingly though, is the environmental work that is undertaken when the wind farm is constructed.  In the North Sea, Monopod style turbines are used.  These are placed in position and then hammered into the sea bed.  To avoid disturbance to sea creatures (dolphins / whales etc etc), a ring is planted on the sea bed around the site before hammering starts and these emit bubbles under pressure.  This creates an underwater sound barrier so that the hammering sounds do not impact wildlife.

Once the base is in position, often they lower additional sections that act as artificial reefs, increasing wildlife in the area such as clams / shellfish,  fish, seals etc.  In fact,  the base also has opening in the bottom for cable access, Seals regular catch fish and then shelter from the sea in the base of turbines to eat their catch.  Apparently,  there's a very fishy smell inside.

It’s only when you get up close you realise just how big these really are and begin to marvel at the engineering that is involved to place these out at sea. 

The turbines are chained in a string which is then sent to a sub station. This then sends the power back to the mainland. 

For Lincs, engineers travel out to the wind farm to work during the day. The larger wind farms further from coast such as Hornsea 2 (which cannot be seen from land) are 5+ hours away. Engineers for those spend 2 weeks on board ship before rotating off.  These ships have helipads to allow faster transfer to the mainland. 

Another interesting fact;  when you see a turbine which is stopped, with a single blade pointing up it is under maintenance and possibly have engineers planning to work on it or already on it. If on the other hand, 2 blades are pointing up in a Y shape,  maintenance is complete and it is awaiting be put back in service. 

We spent nearly 2 hours close to the turbines before the 1.5 hour return journey where we had an excellent packed lunch. Unfortunately,  the sub station is normally crawling with Seals, but there were none to be seen during our trip.  We were also very fortunate with the weather, it was very calm and although cloudy,  the rain stayed off throughout the trip.

When we returned we returned our hi viz and life jackets to the control centre. We were also issued with some Octopus merchandise.  One interesting item was a small number of mini octopi called Constantine.  These, we have found, my 1 year old grandson is terrified of; so if there is part of the house we do not want him to go to, we place a Constantine on the floor in front of it.  Star Trek / Force Fields, eat your heart out;  all you need is a 1 inch tall pink fluffy toy and you have a containment field that can resit the temptation of a 1 year old.  The unfortunate by product,  is the dog loves them and they never stay in their designated location for long.  They, seem to be attracted to the dogs bed, which I am sure David Attenborough would find most interesting as they must have some migratory tendencies that have not been published.

This was a really amazing experience and I can’t thank the team from Octopus enough.  If you get the chance you should really give it a go. 

I would like to take the opportunity to thank Octopus for their hospitality,  time taken to share a wealth of knowledge and an experience I won't forget.

Thursday 2 February 2023

A Year of Solar and 6 Months Heat Pump

It's been just over a year since we had our Solar installed and 6 months since we had the heat pump installed.  I've had a couple of people ask me how it's all been going, so thought I would do a brief update.

So first of all, our timeline.

  • 7th December 2021 - Solar Installed.  This was 17 panels and an 8.2 kWh Solar Battery.
  • May 2022 - Energy Efficiently Improved Our Home and Applied for the Heat Pump Grant
  • July 2022 - Heat Pump Installed
  • Aug 2022 - Got rid of the Gas Fire and Hob and moved the house to completely electric
  • Oct 2022 - Got a second 9.5 kWh battery installed and an EPS setup.
  • Dec 2022 - Had an Audit by OfGem
So what has all this meant ?  Well first of all, look at our energy consumption.

Our Energy Consumption from the Grid

So you can see our energy consumption for 2022 is significantly less than it was for 2021.  Typically our overall KWh consumption is around 50% of what it was before the changes.  Bear in mind I am running an electric car as well.  Also bear in mind, that for most tariff's,  electricity is nearly 3 times the cost of gas,  so we're probably around breaking even in consumption cost terms.

Solar Results

If you consider the electricity we have generated month on month, you can clearly see great levels of solar production between March and November.  In November, with the cold spell and the heat pump warming the house,  we had much less surplus electricity to sell back to the grid.  But the results are definitely encouraging.

Solar Generated and Sold

So our primary goal for solar is to be able to run as much as possible without huge grid demand.  Hence the batteries,   we would rather charge and consume our own electricity, saving 38p / KWh rather than sell to the grid and earn 5p / KWh.  Government if you're reading this,  the SEG rates are rubbish and really need to be improved.  

Octopus do do a 15p SEG,  but it's not compatible with the Octopus Go / Octopus Go Faster tariffs that give very cheap overnight electricity.  Our savings for Octopus Go Faster far outstrip how much extra we could earn on the SEG.

Solar Batteries

One question people often ask is,  are the batteries worth it ?  Well, charging excess into them in Spring, Summer and Autumn to use overnight, plus charging them at cheap overnight rates in winter means they definitely are.  In fact,  being able to use the batteries for a large part of our demand means that,  our average cost per KWh per day in winter is around 19p per 24 hour period.  Around 50% of our day time tariff rate.   

So a huge saving, when you consider we are still using considerable Grid energy during the winter months.  In fact, if I look at the electricity purchased, this month, it would have cost £490 as opposed to the cost of electric we have purchased overnight and used during the day, our bill for the last 30 days is £226.

In addition,  the national grid has been running trials this winter, to avoid potential power cuts and we've been taking part.  Being on Octopus, having a smart meter and batteries puts us in an ideal position.  The idea is,  24 hours in advance,  we will get notified of a time period to reduce our electricity demand.  Each KWh we save,  we get around £2.25 paid to us.  So we have taken part in 7 sessions,  each session has been 1 or 1.5 hours.  All we have done is avoided using any expensive items (dishwasher, washer, tumble dryer, oven, hob, kettle etc),  turned off the heat pump, watched tv on the laptop / iPad and switched to the EPS batteries for our lighting.  So far, we have been paid just over £50 in savings.

Having an EPS

One other advantage of having batteries, is the support for an Emergency Power System.  Here, the inverter will, during a power cut,  switch over to the batteries.  Now the batteries are only able to run with a maximum load of 2.6KWh.  So, when the inverter switches it only handles the lights plus a plug socket in the garage.  The heat pump, normal sockets etc all lose their power.  However, it's pretty nice in the event of a power cut not having to worry about candles or trying to feel around your house in the dark.

We're able to set a reserve power limit (e.g. 20%), the batteries should retain this percentage for use by the EPS,  but GivEnergy have a bug at the moment that means it doesn't always work and a new firmware release is due shortly and should fix this.

Heat Pump Results

It is really funny when I talk to people about having a heat pump,  it is hilarious how many people have opinions about a subject they know absolutely nothing about.  In fact, some of the statements people have said to me and my wife include :-

"I would never have one because they can't heat your house more than 18 degrees which is too cold"

"I would never have one because they are noisy"

"Energy cannot be 300+ percent efficient,  it's too good to be true"

"Electric Costs more than gas so it's not saving"

"It costs too much to install"

So, first of all,  our heat pump can easily heat our house to 25 degrees (and we have done it to see).

In fact, unless the outside temperature drops below -20 degrees C,  I think the house will remain toasty warm.  We had new radiators sized for the house and the house is the warmest now since we moved in 28 years ago.

Even when it's running at full power,  it's pretty quiet too.  And the 300+ percent heating efficiency is possible.  Our heat pump at full power, is operating at just over 3x,  i.e. every KWh of electric we put in, we get 3KWh of heat indoors.  This is because,  it's not really an efficiency of heat generation in a close system, it is the fact that all a heat pump does is move heat, from the air outside, into a liquid that's used inside.  Provided the outside has enough heat (i.e. is above -20C), we'll be toasty warm inside.

So people say, if it's freezing, there is no heat.  Well, at absolute zero (-273C).  There is no heat,  every temp above this has a level of heat.  So 0C has quite a lot of heat in it,  so as long as you have the right heat pump and the right refrigerant, it will work just fine.  If it ever gets to -273C in Yorkshire,  I think I might me worried about more than the Heat Pump !!!!

The one question I have been asked regularly that does make sense

"Can you run the Heat Pump from Solar?"

Quick answer, yes, but...... longer answer is that,  during Summer when all you need is hot water and you are generating surplus electricity,  you can run the heat pump easily.  In fact, your hot water will probably be totally free April - October.  However,  if it were very sunny in the UK in winter,  then when you needed to heat your home, you would be able to run it from Solar.  However, in the UK, Solar Production is down during November, December, January so we would rarely generate enough electricity to run the heat pump.  But what you do generate,  can go into the Heat Pump and reduce your bills.

Heat Pump Grant

Many of you readers out there will recall that the government provide a £5k contribution to the cost if your house is a D or better rating, you have loft insulation,  you have cavity wall insulations etc.  You may recall we got an A rated EPC and were granted the money.  The heat pump being installed in July.

Something for you to be aware of,  in December we received a communication from OfGem, where they wanted to visit,  carry out an audit and verify that the works were carried out correctly,  that the house EPC really was correct and that the grant has been correctly utilised.

Well, they visited,  and except for a couple of slight hiccups, everything went OK and they have written now confirming that the audit was successful.  But if you get a grant beware about our two little hiccups below.
  1. On proving we own the house they demand a mortgage statement to prove your own the house.  Having not had a mortgage for over 10 years,  we couldn't do this.  It took two attempts with presenting the title deeds before they accepted them. Make sure you have access to the deeds and can show them if you do not have a mortgage.
  2. They also complained to the installers,  stating that the heat pump did not 100% heat our water via the heat pump and occasionally the immersion heater is used.  But this is because the heat pump usually heats the water to 55 degrees C.  Unfortunately,  the water has to be over 60 degrees to kill legionella.  So once every week or two,  our cylinder boosts the temperature to over 60 degrees for this purpose.  This had to be explained to the auditor, which seemed strange as they should know this.


Well it's been an exciting year of change.  Being a bit of an IT Geek, we have a data warehouse with 30 minute meter readings taken from the last year and a half,  30 minute snapshots of Solar Production and Grid Import / Export,  Battery Load and even statistics showing whether the house is using Carbon Friendly electricity or not.  

Household dashboard

This shows a snapshot taken on my energy dashboard, showing actual solar production against forecast,  grid consumption / battery consumption and real time costs.

I have built all of the API integrations into both the data warehouse and a home assistant dashboard including integrations with Octopus Energy, GivEnergy Inverter to provide a real-time (well 30 minute delayed) view of the house consumption.  These are all presented on an always on tablet,  that provides a view of the house energy at any point in time (as well as being able to access cameras, plugs, door bells etc etc). 

Oh, and, the rebel can't believe just how much we have saved over the last 12 months.  Yes, with the cost of living crisis, most things are now costing us more than when we started years ago on our climate journey.  But our costs to run the house are maybe 20 % higher than 18 months ago (and I am now running my car in that as well, so the fuel saving alone means we are better off than before, and significantly better off than many people who's electricity and gas bills have sky rocketed).

I am so excited that our share of Wind Farm comes on-line at the end of 2023 to save us even more.

Update - 21/02/2023

For any of you that are getting Solar and Batteries,  Octopus Energy have recently announced a new tariff specifically for people with Solar and Solar Batteries.  Called Octopus Flux,  it pays considerably more for peak solar (23p per unit was our quote),  and has a cheap tariff 2am to 5am ideal for topping up those batteries.

If you're interested and not an Octopus customer,  use the referral code below,  you'll get. a £50 credit on your bills (and I will too).