Finding the chase and cutting to it

There are about 30 million dwellings (residential buildings) in the UK.

As of early 2025, over 1.4 to 1.6 million of these have solar generative capability. Only 44,000 are making use of solar thermal panels. With the rising price of energy and fuel, is that likely to change?

Owned versus rented.

One of the biggest obstacles are that people are less likely to invest in solar technologies if they don’t own the building they are living in. Around 10.5 million homes are in this situation. At which point it becomes the property owner’s responsibility and as all rented homes need to be a certificate C by the 1st October 2030, and solar panels are an easy way to do this.

Challenging some assumptions about solar.

So let’s look at what is holding the other 17,900,000 buildings from doing this.

I have lease hold.

People are worried that their leasehold might not permit them to install things like photovoltaics or solar thermal heating panels. So, ask whether that assumption is right. What’s the worst that can happen? You already don’t have solar, and they might say yes.

It’s too expense.

If you haven’t looked at solar in a while, the prices might surprise you. 4kW systems come in for between £5,000 and £8,000, including installation. Scaffolding for taller buildings does make it more expensive.

It’s not worth it without a battery.

We had solar for 10 years without a battery, and it was definitely worth it. We have a south facing roof, which is perfect if someone is in the house all day, but it means we don’t have meaningful generation until 8am in the summer and 9:30-10am in the winter. We also don’t have much, even in the summer, during the early evening, when we could actually use it.

Which brings us on to the most common misconception.

It’s only worth it if you have a south facing roof.

It’s true that the peak of the sun’s path falls to the south (in the UK, obviously the north in Australia, Argentina, etc) all year round.

But in the winter, the sun rises in the southeast, and in the summer, it rises in the northeast. So, south facing panels lose many hours of potential generation in these early hours. The sun sets in northwest in the winter, and southwest in the summer, again meaning those due south facing panels are missing hours of peak time. This results in the familiar dome shaped pattern of generation.

If your panels were on the east and west, those shoulder levels would fill out with a big dip in the middle. Here’s the comparison, drawn by Gemini.

The total would be a little less, 18.2 kWh compared to 22.4 kWh. But that’s a fair amount of power.

With 3-4 people living in a home, the total typically used in a day is approx 11.4 kWh and most of that is consumed in the following way:

Time	Appliances using electricity	Amount of power used
00:00 – 07:00	Sleeping.	2.1 kWh
7:00 – 9:00	Showers (electric showers are massive power draws), kettles, toasters, and hair dryers.	1.5 kWh with peaks of 3kW for boiling a kettle.
9:00 – 16:30	Fridge-freezers cycling on/off, routers, standby devices, and background heating.	2.5 kWh (typically 0.3-0.5 kWh per hour).
16:30 – 20:00	Cooking dinner (oven, hob, air fryer, toaster, kettle), lighting, TVs, and laundry.	3 kWh, which peak loads of 3-5kWh to warm oven or boil water.
20:00 – 23:59	Entertainment time and sleep.	2.4 kWh.

So, having a south facing roof isn’t great during the working week.

Given that the typical cost of electricity is £0.2769 that day has cost us £3.18. So a year’s usage is £1,159.10 just for the working week, we then have 104 weekend days where that rises slightly, so our 11.5kWh heavy power user is the spending 14kWh during the week (more home cooking, TV watching, etc). So 14*104*£0.2769 = £403.17, giving an annual bill of £1,562.27 plus the standing charge.

If those east-west panels can ease that by 18.2kWh on a good spring day, doesn’t that cost in, especially as you wouldn’t have the outlay of batteries?

So, we should look into it?

Yes, it really is worth considering. But do think about what you need. As a heat pump owner, our south array of panels are not ideal without changing how our heating works or buying batteries, and I would say that the former is more cost effective.

We are examining having east and west panels to cover the morning and evening load. The battery would then be there as back up for a cloudy day.

You could use an app to do a self-assessment: I happen to know of one being launched on 6th April that will allow you to work out if your roof geometry if viable! Or get an installer out, who can do a full shadow analysis and recommend what you should do.

Of course, if you have a garage or garden, solar panels on your roof is not your only option. I know three people who did not want to put panels on their roof, so had a ground mounted array. A sturdy pergola could support an ideally facing array that could be clear of shadows…

Please note that on the first of April, the capped electricity prices in the UK will drop to £0.2467 per kWh. It is widely expected that will be short term relief as Ofgen is likely to put the cap back to £0.27 or possibly higher, depending on the current restrictions on the transit of oil.

NB the graphs shown are real but idealised days with little cloud cover and no shadows falling on the photovoltaic panels in late March 2026. It is true to say east and west panels do not give the same maximum potential, but in many cases they may provide a more useful pattern of generated power.

11.5kWh of week day usage is a high consumption rate in the UK. By comparison, highly efficient households use much less. To work out your average, make use of your smart meter or take a measurement on the 1st of next month (ideally at midnight), and a measurement of the last day of the month (ideally at 23:59), and divide the total for the month by the number of days. In most working households, where the home owners who commute to work, the weekends typically use 1.3 times as much electricity as the average weekday.

Mothering Sunday was not originally about celebrating Mother’s Day – it’s an old age tradition where people returned to their “mother church” – the main parish church or cathedral where they were baptized or raised. This act of returning home is the original meaning of “going a-mothering”.

It is celebrated on the fourth Sunday in Lent, the lead up to Easter and the equinox (equal day and night, only not really in northern latitudes like the UK). Easter is set as the first Sunday after the first full moon (the “Paschal Full Moon”) occurring on or after the spring equinox (March 21). So, Lent and Mothering Sunday change date every year.

For my usual category of Driving off The Grid, equinox and equilux (properly 12 hours of each in the UK), we care about this because the equinox is the begining of Spring and better chances of peak solar generation.

This year was no exception, as the pie chart from NESO shows: one of the first days in a long while where our zero carbon generating sources featured solar power.

The past week, our electricity has come more and more from our own photovoltaic panels, and any excess we have generated is put into the batteries first.

Obviously, this is important at the moment as energy prices are likely to be volitile for a while.

Living in a rural part of the country, our local news has featured the rise in heating oil costs, and a number of people have had their oil drained by theives.

We were on the gas network; when we got the heat pump, we had our gas meter removed and the pipe sealed but not removed.

But the heat pump and solar cells will cushion us over the summer while chaos is happening elsewhere in the world. Not as much as we would be if the UK was not still using gas to generate 30-40% of its electricity. The move to renewables has never been more important to give the UK generating independence.

The graph I grabbed at 2pm on the 15th March 2026 is all the more important for the fact it does not feature any gas generated power.

How has the UK made the move?

The decision was made to place a green levy on energy prices to support the financing of zero carbon technologies and sources. But it has allowed gas prices to be significantly cheaper than using heat pumps for central heating.

Typically, the levy is 13% on a unit. Our unit price is currently £0.2695 ex. VAT, so the green levy means a unit costs £0.2384 and the levy is a whole £0.0310.

“According to the Insulation Assurance Authority, [the levy] has resulted in a reduction of over 26.2 million tonnes of carbon emissions and a reduction of fuel bills by a total of £6.2 billion.” [ https://www.theecoexperts.co.uk/news/green-levy ].

While the levy doesn’t account for much, because gas is so much cheaper than electricity, the efficiency of a heat pump does not look like it costs in for many people.

If we moved the levy away from electricity and put it largely on gas, that comparison would be much more compelling. There’s a good arguement to do that.

It would also make solar cells more attractive. During winter, generation can be hit or miss, highly dependent on cloud cover. But we typically generate 3.6MWh a year, 2023 is a typical year:

In March, with the heat pump, we start to break even in terms of getting enough solar power to dent our bill. By May, despite significant shading from trees, we are effectively off-grid and the money we pay every month is providing savings for the winter months. That and the SEG (Solar Export Guarantee) essentially pays for our winter heating.

I recently found an energy quote from 2008 where every unit was £0.089 – a whopping third of the price of a unit today and prices are rising.

The government could respond by raising the grants for moving to heat pumps for heating. But moving the levy to just gas would help encourage people who are needing to fix or replace the boiler to see real benefit in moving to heat pumps. Ironically, in rural areas, where mains gas is rarer, the uptake of heat pumps has been much higher than in towns, as being without electricity is much rarer in the UK than being without mains gas.

If you live in the UK, you energy company is probably making a big fuss about “Power Moves”. Part of demand flexibility schemes are operated by National Energy System Operator (NESO) as a means of ensuring the UK makes the most of the renewable energy it produces.

Power move, first launched by Ovo in 2024, looks at ensuring you use as little energy as humanly possible during peak times. Because renewable energy is only available when it is being generated, this should encourage people to make use of power when it is available, as much as possible.

As gas prices are rising at quite a rate at the moment (though nothing like as fast as they did in 2022 when Russia invade Ukraine for the first time), as seen in https://www.cliffordtalbot.co.uk/energy-prices/. Please see the image below which is a snapshot I took when I first wrote this article.

This graph is interesting because where gas prices rise, so too does electricity (and oil). While the UK has made great strides in becoming energy independent, we still generate 30-35% of our energy from natural gas and most of that is imported. Things like the action in Iran which exports a great deal of oil and gas, or transists other countries exports, make a big difference, at least in the short term.

The reason power move is so important is that it allows you energy providers to sell you renewable sourced electricity during the rest of the time and when peak demand is happening, they only have to fall back on gas sourced energy for the few who cannot avoid using power – like councils lighting streets and traffic signals, hospitals feeding patients and lighting wards, etc.

Power move rewards customers using power during non-peak times by charging a lower rate, and if they can avoid using power between 4-7pm Monday to Friday during the winter, or 5-7pm Monday to Friday during the summer, they get “prizes or credits”.

I know some using off-peak times to charge batteries which they then use during peak times and when their solar cannot power their houses. It’s not necessarily reducing their carbon footprints but it is allowing them to reduce costs with their providers.

Around 100,000 people are making use of Ovo’s Power Move to great effect and allowing the UK to reduce its reliance on imported gas.

Are you doing this?

The short answer is no. Being type 1 diabetic, moving meal times can be extremely difficult and that is our big use of power between 4 and 7pm.

I do heat soak the house during lunchtime, which reduces our pull on the grid dramatically. This is actually a good example of this in play:

You can see, on a relatively cloudy day, our solar generation was on 2.7kWh for the whole day, we used very little between 4pm and 7pm. Indeed, by heating the house at solar noon for two or three hours means we have a comfortable house, without having to draw anything from the grid.

Teamed with the uptick in our solar generation figures as we enter March, and it all looks much more feasible.

We’re looking at how we could encourage the battery to store energy during off-peak times, and use its stowed energy during the peak. This is standard functionality from many battery providers, allowing you to be off grid when it comes to cooking tea. If you didn’t have that functionality, you may need to do something manually.

Pairing this with ensuring things like using washing machine is done outside of the peak times, ideally during the weekend (we try, where possible to do our washing and dishwashing cycles when we are generating power, even in winter), and we typically only draw a few kWh during the cooking cycle. Which only lasts 20 or so minutes.

The kettle is one to watch. Switching on the kettle uses 3kWh for about 3 minutes for a couple of cups of tea. Making a flask of tea at mid-day might be the way to combat that or take the advice my mum was recently given in helping her sleep patterns and don’t drink sources of caffeine after noon!

And ventilation fans. Making sure these can be kept to a minimum can all help lower your usage during this critical times.

You’re considering it then?

Yes. We really are. It’s about making sure it works for us. The credits and prizes are less tangible than lower costs when it’s off-peak (who remembers economy 7). But it would mean energy sovereignty.

It’s my week to shop and cook. So, I am trying something new today, cooking my lovely left-over pie in the combination microwave.

The average UK home spends 3-4% of its energy usage on cooking. It spends 80% on heating. Which doesn’t make cooking sound as if it’s causing much of an issue.

But, our evening meals contribute to the peak draw on a week day evening.

Given, our heating was 3,966.20 out of 9,594 kWh usage last year, or 41% of our energy bill. Our car was 2,000 out of 9,594 kWh, so 20%.

As we’re keen cooks, let’s say cooking took 5% of our bill, that’s 479.7 kWh.

So, without switching to sandwiches of an evening, how can we do better?

Well, it’s one of the reasons the microwave is being deployed for the left-over pie. Instead of using the hob for 15 minutes, I cooked the filling in the microwave for 6 minutes at 1kWh. That gives us a usage of 100 W compared to 600 W for the induction hob.

Normally, crisping the pie crust takes 28 minutes at 2kWh, or 933 W. Doing this in the microwave will take 15 minutes, even if it uses the 2 kWh, that’s 466 W.

It’s not much towards the 479.7 kWh, but hopefully it is a step in the right direction. And much quicker to boot.

OK, I give in, what do the numbers all look like, please?

Task	Induction hob or fan oven energy usage (kWh)	Time taken (minutes)	Microwave or Combination microwave enery usage (kWh)	Time taken (minutes)	Power saving as %
Vessel heating for filling	~0.15	1	~0.01	0	93%
Filling precook	~0.50	20	~0.10	6	80%
Finishing off pie	~0.90	30	~0.25	12	72%
Total	1.55	31	0.36	18	77%

The microwave uses 23% of the power. It takes just over half as much time (well 18/31 = 58%).

So what did it taste like?

Pretty much the same as normal, it’s something we look forward to having each week, almost as much as cooking the roast on the Sunday before hand.

The food was just cooked in a fraction of the time and energy. In fact, I was so impressed, I am using the same methodology for the pudding we often do with the pie, a tart tart. Using the remainder of the pastry means we get to use the residual heat from the oven, so the pud is really economic.

These are not new concepts. When ovens were powered by wood and coal, the Sunday lunch was often followed by cake or bread, soaking up the residual heat. It also made short work of food that went off in the cold store, like eggs, milk, and butter.

Of course, most working people do not have the time or energy to do that. But when everyone cooked their bread at home, a roast joint popped in the oven afterwards on a Sunday was basically free cooking. As was the scones or cake for a high tea…

Makes sense, so how did that experiment go?

The initial timings were a little off. Because the combination oven was pre-warmed, it didn’t need anything like the 12 minutes I cooked the pair of tarts for, but next time I will do better.

Taste-wise, it’s the same, energy-wise, it’s much quicker: so why don’t more people do this?

It’s a good question. 90% of UK and USA homes have a microwave.

There is a move towards combination microwave ovens, especially in smaller homes as they provide so much functionality in a smaller package. But cooking in a microwave is still seen as a bit niche.

For me, this is such as missed opportunity. Using 25% to 60% less energy for a cooking task means our 479.7 kWh pa on cooking goes down to a conservative 239.85 kWh. At £0.27888 per unit, that’s £66 pa. Or runing a tumble dryer for 80 hours.

Then there’s the washing up. The pudding comes for free as it uses the lid for the meat pie dish.

But usually, I would use a big pan to pre-cook the vegetables. This is no longer needed. I would have used oil to cook the veg in too, again another saving, and if I use the right knives, everything would fold into the dishwasher.

This is another reason I am making the effort. I am trying to start my own business, and until it is established, things are busy without bringing in any cash.

I need all the help I can get, and such differences do add up pretty quickly.

How are you making the move to using the microwave more?

Actually, Google’s Gemini is acting as my sous chef. Given an existing recipe, it’s quite good at making the conversion.

I give Gemini the link to my wiki recipes and ask it what the steps would be if I cooked it in the microwave. It was a little involved for this one as the recipe had the multistage cooking – going from the hob to the oven. First draft just gave me swapping the fan oven for the combination microwave: but a little coaxing meant I had everything being done in one pot and one device!

As per Zapping my way to the top, there are a few easy moves to make.

I do have some ground rules for sanity checking what Gemini says, but so far, it all seems to be positive steps forward. Good tasty food cooked quickly and cheaply: why not make that effort?

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I’m no saint. Yes, I have been the one to make the suggestions of looking into the electric car and the heat pump, but, like everyone else, there are big areas I, personally, should do better.

We are alpine skiers, and living in the UK, that means foreign travel to some mountains. Last year, we did the trip to France by train (if you are looking for an eco-friendly trip, this is the way to travel). In fact we did a great deal more eco-travelling than normal to off-set our trip to Canada this year.

I know, I know, two rights and a wrong do not make things good. But I should be able to do much less by car over the next twelve months too, and hopefully make more use of my push bike…

Your point?

Sorry. I was going to talk about the big difference in doing such trips when you have an optimised heat pump.

Before the heat pump, when the house was truly deserted, we would put on frost protection and run the house at a really low level. But, having got the windows done, and the curtains, it really isn’t the right thing to do for the heat pump. Plus my son and his girlfriend house sat for the weekends, so the house wasn’t really empty over the period…

What difference did that make?

Let’s have a look. We were away from 10^th February to the 25^th February 2026. The doors and windows were all closed, as were the curtains, and we can see that the usage wasn’t that different. The days when no-one was around, the usage was pretty low, but then those were much warmer days too. More importantly, they were sunnier too!

I did make a difference to the Vicare app, and turn down the settings for the flow round the heating circuits. Fewer doors (both internally and externally) means the temperature didn’t change as much, so we didn’t need as much heat flowing round the system, especially when teamed with room thermostats. I also stopped the post-tea warm up when there is less demand on the grid.

That sounds like jargon, what do I mean in practice? Well, in our living/entertaining areas, I have set the heat to come on again at 19:00 or 19:30 to take us through the part of the day when we’re more likely to be less active, talking rather than walking, so to speak.

The 17^th February in the lounge (I so want to say with the candlestick, but I will refrain), is a great example of this.

The yellow area is when we heat the room for a few hours in the afternoon, just post our solar peak elevation. We can see from the graph, that heating effect actually continues for much longer than the heating time itself. During this time, I am leveraging our solar panels, as this is when we’re most likely to be generating on a cold winters day in February.

Let’s look at the same graph after I had put the timers back to heat during the evening and returned the flow temperature back up a couple of degrees.

What’s interesting is while the heat is primed to come on, it doesn’t actually reach a temperature where the room is aggressively heated as it is still carrying the heat from earlier in the day. That evening heating is to keep the temperature stable rather than heating a cold room.

Let’s have a look at those heat settings for Thursday.

The solar soak is happening between 12:45 and 15:00 every day. To quote Google:

We are not making the “power move”, to ensure our usage is as low as possible during these times, but we feel every little bit we can do all helps.

I have set the lounge, offices, bedrooms and en suites to make use of these kinds of patterns. It’s not zero, but it’s not taking more than we need.

On a day where there wasn’t that much sun, we can see the corresponding peaks in our pull on the grid.

On a day when we are generating electricity, it’s really noticeable, even in February… Wednesday the 25^th February, while I was putting everything back to “normal” for our return, our house was drawing very little from the grid. We were managing to charge our batteries to take us through the evening.

These changes you’ve made are working then?

They do seem to be. Heating the house during the times we have energy from the roof, not drawing too much from the grid during peak demand are worth the effort.

Compared to usage up to the 26th February 2025, we have used 170.7kWh less electricity, about £45.25 (and last year the electricity was more expensive).

We haven’t changed anything else, and February 2026 has been cooler than February 2025, and darker. I can prove that because we’ve generated significantly less electricity than last year!

Oh, so that isn’t just you using less from the grid, you’ve actually used less per se!

We’re making it count. Both years have been using the heat pump, but getting the insulation right with the windows allows us to make simple changes to our behaviour without making us uncomfortable. Far from it, we are warm and the house is definitely working for us. Over the course of a day, the lounge is heated twice a day, as many people set up their homes, it’s just making the most of what we’re actually generating and using.

On the 26th February 2026, we were using very little power between 16:00 and 19:00. So much for electric heating making greater demands on the grid and we didn’t need to be cold to achieve this.

Strolling through our local town centre or talking with family, it’s tempting to think that the grey skies overhead this UK winter are a sign that climate warming isn’t really happening.

Actually, they are almost certainly a symptom of climate warming in action. Compared to the past few Novembers, November 2025 was dramatically warmer and wetter. In our little bit of the world, temperatures were in the low to mid teens Celsius (55-62°F) for the first half of the month. Even when they dropped, between the 19th and 21st November, they rarely dropped much below freezing for long. Typically, in November, the nights stayed around 5.8°C.

Rainfall was significantly heavier in November 2025, nearly 1.5 times as much as expected. That might sound like good news as we’ve had very dry summers, but as we enter the second week of February 2026, the rain hasn’t stopped in some parts of the UK for 35 days.

November was a bit sunnier (despite the wet weather) too.

December 2025 was cooler towards the end but had a warm day on the 9th December of 12.5°C, a whole 7°C warmer than usual. It was drier but when the cold weather came in, another Artic blast like November, starting over the Christmas period. No, that didn’t bring snow.

January 2026, was cold. 0.5°C less than the average temperatures. In Marham, Norfolk, temperatures dropped to -12.5°C on the 5th January!

Our part of East Anglia is typically much milder by comparison. One of the benefits to living in the urban sprawl, is the council grits the roads and the sheer number of people keep things that little bit warmer. The towns in the area are typically 1-2°C warmer than the villages as a result.

Bad in the summer, but a blessing in the winter.

2025 was the warmest year on record for the UK, although we lacked the baking days of the summer 2022; 2022 had lower average temperatures though the high extremes were just that.

It’s the averages that matter. The UK benefits from being an island archipelago featuring a large number of inhabited islands: Northern Ireland and England, Wales, and Scotland being the significantly populous ones. It sits within 11 degrees of latitude and 15.5 degrees of longitude, which means what is happening at the south-westerly point is very different to what’s happening in the north-easterly point, weather and climate wise.

In my area, we benefit from a couple of things: longer days in the summer and winter, making solar panels worthwhile for home generation. We have a coastline, making off-shore wind power accessible at scale. It’s sparsely populated, having been agricultural for a long time, though the plans to build many more homes will change that.

East Anglia is also deemed semi-arid, by UK standards. We get little rainfall. The rain in mainland UK comes from the west. Which suggested the weather late 2025 and 2026 has been dominated by Atlantic weather systems. As lay people call it, specifically, the Gulf Stream.

The Gulf Stream is a current traveling from Mexico, past the USA east coast before bending towards Europe. Mexico is on the Tropic of Cancer, and unlike the Equator, these latitudes are seasonal and typically warmer than the latitudes to the north and south of these boundaries. They have seasons as a result, much like the UK, though milder winters at sea level than a relatively northern island group like the UK.

The UK should be a cold little set of islands in the winter, but the Gulf Stream contributes to the Atlantic Meridional Overturning Circulation (AMOC) which changes that by bringing milder weather up to us from the Tropic of Cancer. AMOC does this by acting as a conveyor belt: warm salty water flows towards the Artic where it cools and sinks. Colder deep water then flows southwards, completing the circulation. Freshwater from melting ice can reduce salinity and slow this sinking process, weakening the system..

One of the concerns with climate change is that the AMOC depends on differences in water density, driven by both temperature and salinity, to keep it circulating. As the climate warms, increased freshwater from melting ice can reduce salinity in the North Atlantic and weaken this circulation, potentially reducing the amount of heat transported towards the UK.

This is likely because as temperatures rise, more ice melts in the Arctic and around Greenland. This happens naturally each year, but climate change increases the overall amount of freshwater entering the North Atlantic. Ice is made of fresh water, so this added input reduces the salinity of the surrounding sea. Lower salinity makes the water less dense, which means it does not sink as readily in the far North. Because this sinking helps drive the Atlantic Meridional Overturning Circulation, reducing it can weaken the system and reduce the amount of heat transported towards the UK.

It’s February, so how can this be the topic of a post today?

Or Solar elevation and what it means for me…

Human beings have been interested in how high the sun gets in the sky since ancient Greece was a dominant power. In fact, the Greek astronomers founded an equation anyone can use to work out the elevation of the sun at any point in the earth – this was the foundation of sailors being able to navigate the world long before GPS was a twinkle in anyone’s eye.

To our modern, land-locked people, it helps us work out when sunrise and sunset occur and, in terms of generating solar power, when the peak can be expected.

The equation is h_max=90°-L+δ, where h_max is the height the sun reaches, L is the latitude of your position on the earth, δ is the declination from the sun to the earth which varies from +23.44° during summer solstice to -23.44° during the winter solstice (in the UK). Declination is the angle between the sun and the equator at the point of time being discussed. In this case, we’re looking at the maximum angle in a day.

My latitude is about +52°, so during the summer, our h_max is 90°-52°+23.44° ≈ 61.44° (read this as approximately equal to). During the winter, 90-52-23.44 ≈ 14.56°. We can see how this changes in the table and graph below.

This results in a solar elevation in Ipswich of….

So, for our little corner of the world, we can see that indeed the sun’s height wobbles between 61.44° to 14.56°. Which is fine and dandy.

A valentine’s gift…

As seen in the graph, during the year, it varies between that maximum and minimum of 61.44° and 14.56°. Today is the 14^th February, so it’s about 25.1°. Compared to any day in December, when the elevation was ~16°, it makes a big difference to solar generation potential, and why January and February are so much better for our generation than November and December.

The next consideration is your roof’s pitch (if siting the solar cells on your roof). Given our northern latitude, a pitch of around 53°, as we have, maximises the solar harvesting during the winter, but it is not ideal for during the summer, when a pitch of 35° would be more effective. With a heat pump supplying our heat and hot water, this is ideal for us.

The proof of this is seen in our solar generation figures; we typically generate more in March and April than we do in July. But we don’t need as much energy then, so it suits us.

This matters in terms of solar generation, as solar cells work best when the sun hits them as close to perpendicular as possible. Basically, if the angle is shallower than 60° or steeper than 90°, there is some reflection happening. Indeed, so much is reflected that the generation suffers. During the winter, our roof is ideal, as the angle is well above that 60° floor, but during the summer, the angle is well above 90°. The angle between the sun and your roof matters. If you want to be solar powered over the winter, your cells need to be at a steep angle. That doesn’t mean it’s ever going to be great, short days and all that, but it maximises what you have to play with.

For some, this is an argument they use to say that solar power is not worthwhile somewhere like the UK. I have never found that a convincing reason to not harness an abundant source of power used by plants in the UK for millenia. Of course, plants are a bit cannier than the average human in making the most of what is available…

For me, these changes mean a fixed installation is fine but it would be relatively simple to engineer a system that could maximise the gathering of photons pretty easily – only that is not encouraged in the UK. We go for fixed systems, often targetted at the winter gathering options. Indeed, if you are mirroring the pitch of the cells to the sun’s zenith, why not have simple systems to track the sun across the sky during the solar day? After all, this is what the common or garden plant does to ensure it thrives.

Again, not encouraged in the UK, at all. Our house was built with a due south (180°) azimuth view roof, which is a good compromise. I do not see houses being rejected in planning where that is not the case.

Our roof is limited because we are a “chalet style bungalow” – dormer windows mean we have shadows cast on our solar panels by our need for natural light as humans. Again, why not let the architects build a flat roof in 2012, maximising the potential to generate power?

Our solar generation has varied over the past 11 years between 3.3MWh a year and 3.8MWh with 3.6MWh being the modal generation (most frequently occurring). We don’t really have an easy option to put in more cells because of the roof architecture. We do have an east face we could exploit, and a west roof, but the generation potential of these surfaces is reduced.

Please planners, look at the limitations you are putting on people when plans are submitted, in these terms. What would our potential be if we’d had a standard roof?

Over the past few weeks, it feels like I have spent more time talking to Gemini than to any single person in real life. AI is helping more people in the workplace but what about easing things round the home?

I wondered if Gemini can help me lower my carbon footprint?

Of course, not being human, Gemini needs a question to get started. Mine was “can you help me convert this recipe so I can cook it in the microwave?”

I’ll bite, what recipe is that?

Soup. I know I have a induction hob but putting on a big ring for soup cooking over 40 minutes seems a bit wasteful, somehow.

There are several things I use a microwave for: roux sauces are done in second rather than minutes, fish is incrediable, chocolate fudge sauce is a guaranteed outcome. I know how much time is saved and great food I have enjoyed in cookware that goes straight into the dishwasher. What’s not to love, from that point of view?

Of course, for the “Driving off the grid” section of this blog, microwave ovens are incredible. There is no waste heat, it outperforms induction hobs for the sorts of food you would normally cook there.

My real winners at the moment are my home made yogurt, and the chicken stock.

So after zapping my fish dish this lunch time, I got tapping, exploring what I could do next with making the most of my microwave.

There are three winners, I think. A vegetable stock for my soups, some fish stock made from some fish I’ve cooked (definitely one for the freezer, my partner does not like fish!), and some conversions for my favourite soups.

A vegetable stock to be less wasteful.

Before I got in to cooking from scratch to such an extent, stock seemed like a waste of energy, when you could buy a cube or pod full of tasty stock. Hours bubbling away on the hob, boiling out bones did not sound like my idea of fun, not to mention the washing up.

Finding my chicken stock recipe was a wow moment. But finding a sensible looking vegetable stock seemed rarer than a unicorn, hen’s teeth, and flying pigs. Such things did not seem possible.

In comes a session with Gemini talking about home cooking, so I ask: “I’d love to make my own vegetable stock. Could you suggest how I could do that in the microwave?”

An initial suggestion was refined, working out alternatives to things I knew we were cooking the next day – I wanted to do a vegetable stock for our traditional Sunday evening soup. Well, the stock wasn’t bad, taste wise. 250ml of tasty stock out of things I would normally bin!

For the soup, I put far too much water in with it. When I cook the soup in a pan, covering with water is absolutely necessary. So I did the same with the microwave version – tasty but incrediably wet! Next time, I’ll just add the 275ml of stock.

But the speed, the hands off nature, the lack of piles of hard washing up. I may be a convert!

What about the verdict, beyond the taste, isn’t tradtional soup on a hob better than using the microwave?

It’s really marginal, energy-wise, not least because the microwave is running at 660W for the whole 15 minutes, where as once the soup is simmering, the induction hob is using very little power.

We’re losing some energy with the induction hob to the pan and its lid (85% efficient compared to the 90% of a microwave), but it’s really, really close.

Where the microwave does probably win hands down is the cleaning up process. Using the microwave, I used five pieces of equipment – a knife, litre jug, a silcon lid, a small measuring jug, and a stick blender to cook and serve. All but the small measuring jug goes straight into the dishwasher.

The traditional method uses a knife, a wooden spoon, a pan and lid, a blender goblet, and a ladle to spoon the mixture from the pan into the blender. Six pieces and that’s before we start to break apart the blender goblet and its lid – another five items.

Many of these cannot go in the dishwasher, hello wooden spoon and engine part of the blender goblet, but the pan and blender goblet are huge. Both take space that means the dishwasher would have fewer items for a full run, so often wash them by hand.

Gemini suggested that the induction hob might edge ahead, but I pointed out that for the total cost of ownership, the prize goes to the dishwasher, and that’s forgetting the time I’d be standing on my feet stirring the pot as the dry vegetables get cooked in the butter before the stock is added.

• Microwave = 15 minutes * 660W = 165Wh = 0.165 kWh.
• Stick blender = 3 mintues * 1.2 kW = 60Wh = 0.06 kWh.
• Dishwasher = 50 things in the dishwasher, of which this meal uses 4 of them, which runs at 0.54 kWh, so 0.0432 kWh.

Total power used to cook the soup in the microwave = 0.2574 kWh.

At £0.2656 per unit = £0.07, as a total charge, plus the standing charge.

A cheap evening meal on a Sunday evening, partly made with left over peelings from lunch. Next time, which much less water in it, check out the revised recipe at Microwave Stilton and Celery Soup!

Compared to the induction hob?

Ah, so there are more steps making up our 40 or so minutes of cooking time, but the induction hob probably used around 0.5767 kWh. If we keep the stick blender and everything else the same (though there is significantly more manual washing):

• Induction hob = 40 minutes * various power levels = 0.5767 kWh.
• Stick blender = 3 mintues * 1.2 kW = 60Wh = 0.06 kWh.
• Dishwasher = 50 things in the dishwasher, of which this meal uses 4 of them, which runs at 0.54 kWh, so 0.0432 kWh.

Total power used to cook the soup on the induction hob = 0.6799 kWh.

At £0.2656 per unit = £0.18 total cost, plus the standing charge.

Wait, isn’t that more than 2.5 times the cost, plus the washing up, and the time!

Yes, yes it is. Working out how to do things in the microwave (if possible) really does pay off.

This is another piece on how air sourced heat pumps (ASHP) work…

Oh no, can’t we talk about anything else?

Not yet, and bear with me. This is a fundamental thing to consider when trying to get the most out of your pump. But it helps to understand how a heat pump works to get understand why this makes such a big difference.

Fundamentally, a heat pump, like an air conditioning unit or fridge, uses a compressor to pull heat out of the air they draw in through the fan. ASHP use the principle of heat dynamics and some chemicals that have a low boiling point, that allows it to transfer as much heat out of the air as is possible, into the compressor. This squeezes the gas, generating high levels of heat which is conducted to the heating coils, which heat the water going to the radiators or the hot water tank.

This is why ASHP are so efficient compared to a fan heater or immersion heater, that squeezing effect can be thought of as a multiplier for the heat “pulled” out of the air. The chemical in our pump is propane, and it’s boiling point is -42°C, so basically, our heat pump works well even if the outside temperatures would kill a mammal like us.

The heat pump does have a back up plan, for when the “flow temperature” being generated is lower than the one needed to heat your water or rooms, there is a back up electrical heater.

Which is the point of this post.

Finally! Which is what, please?

When the ASHP was installed, it was given some settings to describe how it should behave.

For the summer, the maximum flow rate (or the maximum temperature coming off the compressor) was set to 50°C, which would work well for us, if we weren’t trying to use our house as a heat store.

We bake the house at midday and, fundamentally, only heat our hot water once a day. As we have solar cells, our time of day is midday’ish – I shift the time based on our house’s solar elevation (I talk about solar elevation on 14th February 2026).

What?

We get free solar engergy off our roof (well not free to install, but we bought the panels many moons ago, so it is free now). Plus, our solar energy is definitely carbon free (their carbon debt being paid off back in 2016, please see Number Crunching Part 1). Making the most of that energy is really important to us for those very reasons – keep our costs down and our CO₂ emissions to a minimum.

OK, I’ll bite, is this your only option?

We could sell that back to the grid and then buy back energy later in the day. But our rates don’t change: Ovo’s Simpler Energy Plan has a low standing charge, so while the units are a little higher than other plans in Ovo’s range, we benefit during the summer when we’re effectively off-grid.

Which all means that our heat pump is not working for us as well as it could for these reasons.

Why is that?

The coefficient of performance (COP) for our heat pump is around 4.1 per annum, that means for every kilowatt hour of energy it consumes, it produces four point one kilowatts of heating. Basically 1kWh = 4.1kWh. That’s made of the electrical heater and the compressor.

The electrical heater has a lower COP, about 1. Our best strategy is not to use the heater unless necessary.

Yet, when I looked at the figures that was exactly what was happening! So far (today is the 24^th January), we’ve used 734kWh in the compressor and 50.4kWh from the heater, so far for January 2026. Why?

Well, the heat pump has a setting called “maximum flow temperature”, which has a little leeway, but it states how much of the flow temperature comes from the compressor. Ours, like many set in the UK, was set to 50°C. Everytime we try to heat our hot water up to 55°C once a day, the electrical heater was being activated. For at least £13.10 worth of electricity, that we shouldn’t need!

So, I’ve set the maximum flow rate to 57°C. This should allow us to get to our 55°C easily without needing to turn on the heater. We could set the max flow temperature all the way up to 65°C, but that might get the compressor over exerting itself at times, and I don’t mind a fiver or so spent to keep everything working well.

Is it really going to make that much of a difference?

Let’s look at last year, if you remember, we can have a look at the way our heat pump used the energy it consummed.

	Total in kWh	Compressor in kWh	Electrical Heater in kWh	Heat generated in kWh
Nov 2024	544	509	34.5	2,330
Dec 2024	603	585	18.5	2,640
Jan 2025	926	863	62.5	3,390
Feb 2025	686	653	32.7	2,720
Mar 2025	486	463	22.9	2,010
Apr 2025	187	183	4.5	1,010
May 2025	113	111	2.0	632
Jun 2025	113	111	02.0	632
Jul 2025	38.1	37.8	0.3	220
Aug 2025	43	42	1	222
Sep 2025	90.7	88.9	1.8	537
Oct 2025	231	227	3.7	1,240
Nov 2025	510	493	16.7	2,130
Dec 2025	617	597	18.4	2,600
Jan 2026	1,000	940	62.5	3,440
Feb 2026	?	?	?	?
Mar 2026	?	?	?	?
Apr 2026	?	?	?	?
Total	6,187.8	5,903.7	284.00	25,753

This is something we’re going to try until April, I will let you know how it goes, probably with a graph.

If we can reduce the power used, because the compressor is more efficient than the heater, it’s probably something we’re going to keep doing!

Is it worth it to save 122.6kWh between January 2026 and April 2026?

From a money point of view that’s 122.6*£0.26 ~ £31.88. Is it worth the squeeze? But if we can reduce our CO2 levels further, it’s got to be worth it, hasn’t it?