Your tech and how it works for you

Think you need to revisit your ROI calcs for solar panels, I'm in N Scotland and generated 4,200 kWh in 2024, even if I just exported it all @15p per kWh that's £630. My PV setup (4.8kw panels, 3.6kw inverter) now is probably £3.5 to £4k installed. I used about 40% domestically, 20% diverted to my tank immersion and exported the remainder. This year the YTD solar generation is up 20%.

Battery costs have also plummeted but ROI is still a few years more than PV.

p.s. also have A2A 👍

I think this is a key aspect in any green energy strategy. You are correct in looking at each setup being unique which does beg the question of how to put everything together for mass market adoption.

I have noted my reasons for moving a few times but the capability to make use of existing tech (already installed solar PV etc) within a tariff on offer is important when choosing a supplier.

The ability to make use of off-peak rates is needed whatever the meter installed (I’m not talking about non-smart meters). With the move to half hour settlement expected, the facility to match this in billing for meter reads would be a huge step forward.

I guess I should say right up front that my primary motivation is not financial but reducing my long term impact on the planet. Having said that I have so much to say on this topic but i’ll start with my view on ROI (Return On Investment). This is very different from pay back period.

ROI is how much return you get on the money you have invested in your technology. I am lucky enough to have had the spare income to have saved hard all my life. I now have a substantial private pension pot. If this is invested for guaranteed income I can get roughly 4% return. If I take this money and invest in solar PV, Heat Pump, Insulation, Battery, EV etc. I can do my part to reduce my families fossil fuel use while also getting a better return on my money.

For instance £10 000 invested gives me £400 per year income. If I take that £10 000 and spend it on solar PV and battery I can save much more than £400 per year on my electricity bill.

I haven't  even considered how long it will take to pay off the £10 000 because it’s income(reduced outgoings) that’s important to me. I could spend the £10 000 on a cruse but get much less pleasure and satisfaction.

I did using my detailed energy use vs daily and seasonal production and the installation costs are much higher due to the last round of inflation. My direct energy use is about 32% but I'm only paying 19p per unit so the rest would go to SEG. Given achievable values of cost and SEG my payback time is 11 years in my particular case assuming there are no maintenance costs (replacement inverters etc). This is where individual circumstances make one case viable and not in another. You need the detailed calculation for generation (quantity and shape) , use (quantity and shape), supply cost (variable in my case**) and SEG rate (could be fixed or variable).

The payback time for a battery (~5kWh but strangely it doesn't change much with size) is longer than the lifetime of the battery. The advantage of having a battery though is if future SEG rates fall. They are likely to do with the very large solar farms coming on line in the near future and Octopus are only renewing SEG with time of use (generation) rates. It's very true that battery costs per kWh are falling quickly but even the installation cost kills the idea although power arbitrage (buying cheap overnight, selling during the peak) may prove to be profitable.

The A2AHP is a clear winner though.

Peter

**Agile complicates the calculation because the rate changes every half hour. Over the past month a lot of sunny, windy afternoons have meant my rate has been near zero.

​@brichard Thank you for your very considered and reasoned reply. I have said in previous blogs that if your motivation is to go green and reduce your impact then ROI or payback time is not even a consideration. You have the money, you invest in the tech and then reap the rewards in terms of an income and reduced impact.

In terms of ROI I have had recent fixed rate online bonds mature that have returned 4.5-5%. If you have a mortgage at 5-6% then it is arguable thet you will get a better return paying off the loan and I've always said that high mortgage rates will affect decisions on investing in green tech. A question is: What is the price for helping to save the planet? The answer is: The price you can afford. Green tech should always be affordable for those who have to choose between one option or another.

This thread was about getting people to talk about their particular circumstances, experiences with the hope that this would help others navigate a green path without making an expensive mistake because they hadn't considered their particular circumstances. I'm tring to get people to ask WHY they are considering these solar panels, that battery system or tariff. I'm also hoping that OVO staff will look at the responses to see how best they can help their customers or potential customers make the right decision and perhaps look at the tariffs they have and see if something else can be offered which is both profitable to them and cost effective for their customers.

Peter

​@BPLightlog We've had a number of useful discussions recently and you've always been spot on. I particularly liked: If you have the tech already then go an find a tariff that makes the best use of it.

If you are starting out from scratch then try and find a combination that works but the whole thing is very much a dynamic situation. SEG rates change. Suppliers come out with different tariffs. The prices of solar and battery change.

Here's a thought. Instead of fitting solar panels how about investing in a solar farm (if indeed that is possible). But, there was a scheme in the north called Ripple which was a wind farm investment that went badly wrong for a number of reasons so it has its caveats.

Peter

Strangely enough, I did also put my hat in the ring on the Ripple investment. The existing projects are actually still producing as once set up and construction is underway, they are then owned by a separate company.

GIven the state of things, it’s a shame that Ripple didn’t survive but there are other options

The point about this thread is that it is here to promote a discussion amongst a group of people who have experience or other information and it was the point about investing in renewables rather than fitting them that led me to this 🙂

https://solarfast.co.uk/blog/solar-farms/

PLEASE, please, please - THIS IS NOT AN INVESTMENT GUIDE! That figure is probably the free-wheeling downhill + following wind return value and I would be expecting something more modest but it does indicate that investing rather than fitting is possibly an option. I would consider doing that as I would see that as being just as green as house solar panels. It also means I wouldn’t be tied to the house waiting for it to be paid off or be concerned about recouping the investment if I needed to sell.

The reason for the return to profit after such a short time is basically the economy of scale. They buy cheaper in bulk and can strike a lower rate for the installation and maintenance.

Peter

To add some more information on my journey and how I got to where I am today. 1930s partially extended house with lots of solid 9 inch brick walls always cold. External Wall Insulation for solid brick work Feb 2022, ASHP with radiators installed Nov 2024, 8kW peak solar panels and 16kWh of battery.

It all started when I applied for a grant to have the house insulated. This improved the could house but not by much, it was still cold. I have never been happy burning loads of gas to keep the house warm. So I started looking at heat pumps and radiator upgrades. I got quotes form 3 suppliers which suggested I needed a 10kW heat pump which would require planning permission due to it’s physical size. I applied and was staggered to be turned down even though the heat pump was 8 meters from my closest neighbor and this is not a quiet neighborhood. I did some more research and talk with my suppliers further and decided to have a 7kW uni t installed with radiator upgrades. The supplier did a reasonable job and really understood how to design an efficient heat pump system. The system has been running all through the 2024-25 winter and I’m really pleased. The house was so much warmer and the cost was just a bit more than I was paying for gas. If I had heated my house with gas to the same extent I have with the heat pump the cost of the gas would have been 50% more than the electricity I used.

To complete my plan I has the solar PV system installed at the end of May 2025 so it’s all still quite new. But I haven't used ant electricity from the gid since the solar was switched on and have exported 580 kWh. At a SEG price of 12p per Kwh from OVO that is £70 in less than a month. Now I know that this is probably one of the best months of the year and I won’t see much solar in the winter but I’m hopeful of having a close to zero energy bill over the whole year.V which I have had for several years.

I’m still weighing up which tariff to go for. I currently have an OVO tariff fixed until September so I’ll decide then. Octopus Go is looking possible but I may well stay with OVO. I would love to se OVO do a battery charging add on so that I could charge my battery ar cheap night time rate to drive my heat pump through the long dark winter days. Octopus SEG price is 15p kWh I think so I would be good if OVO could get close to that.

Please ask any questions if you think my experience might be helpful.

Bruce

Personal view, but I wouldn’t go near any green investment schemes as in my opinion the entire renewables sector is still very much struggling to find a way forward, not helped by a vague net zero ambition that can change dramatically depending on the political ambitions, another good reason to have your own power station on your roof, personal energy security! And its tax free - at the moment.

Yes, everyone’s personal circumstances can impact the viability of renewable installations, for me the Scottish Government 5 year zero interest loan for the PV installation was a big positive and knocked a year of the ROI, probably between 6 and 7 years at current rates.

I’m also with Octopus, was on tracker till April this year, might venture back into tracker but we’re importing so little electricity this year I can’t get excited about it just now, Agile is too much like hard work for me. I’m a big fan of Octopus and their forward thinking strategy that give customers options based on their personal circumstances.

2nd house with the A2A is OVO, was THTC with storage, so A2A is a real revelation, instant heat, fraction of the previous energy use, can, and do, control it remotely. At the end March the house used 8kwh/day to maintain the temp at 20 deg C from 8am till midnight, 2 bed, 2 storey, 50’s built. Of course no government assistance available, but zero VAT at least.          

Hi Bruce

That was exactly what I was looking for when asking for real life experience in using tech. When you say ‘I’ve done this and it works well’ it’s helps other people be confident in following in your footsteps.

One of my concerns was the relative lack of competency in designing a heat pump system. You had the experience of being recommended a 10kW system but having a 7kW pump installed and it working well. The advice is get a number of quotes and ask questions as to how certain that is to be correct. It’s also a good comment on the relative prices of the two systems. It’s very hard to get true before and after comparisons and I pleased that your experience was very positive.

Unfortunately the ratings of gas boilers is no indication of what you actually need. Mine is an 18kW Vaillant Ecofit but my absolute maximum requirement is about 100kWh per day or only about 4kW continuous for a few occasions. When an ASHP engineer turned up to do a survey he looked at the property and said ‘I think this a 5kW job’ which was spot on but when he had entered the data he said it needs a 7kW system with much higher costs. I rejected the quote because I believed it was flawed and DIY installed a 3kW, A2AHP instead and supplemented it with a bit of wood burner, gas and some solar gain. The house was really warm last winter and it was colder than usual. It doesn’t do any harm to look at alternatives instead of just blindly following what your neighbour did or someone on a website said without any context or feedback.

As a bit of commentary on the chart below the gas (blue) was really only used on the coldest days and I only used 20% of what I would have used that year. The A2AHP has taken the base load and I used the wood burner (brown) to cover my peak electricity prices 4-7pm. I also experimented with 4kW of fan heaters overnight when my electricity prices were zero (happens on Agile) and turning the lounge into a heat battery. Didn’t happen that often (only 3% of total heating) to make any real difference though but it caused the heat pump and gas boiler to shut off completely for quite a few hours afterwards. Also, 6% of my heating is solar gain through our large patio doors and window.

Many thanks for your comment.

Peter

Thanks Peter, I have to say the OVO Heat Pump Plus tariff has been great ,15p kWh for all electricity used by the heat pump was a game changer and will probably keep me as an OVO customer. I also have a wood burner which I can use to top up on the coldest days, but not really necessary. My Heat pump also has an option of a top up heater (simple immersion heater for the space heating). I don’t have this option and don’t need it.

I took a while to get my head around leaving the heat pump on all day and night to keep the house temperature constant. But once I tried it I would never go back to on off gas boiler heating. 

Getting a competitive tariff for a heat pump  is an important point. My average domestic rate is about 19p and that makes my heat pump cheaper than gas. In fact I not only reduced my gas use it was also cheaper by about £125 over the winter. That is what I mean about going green but also being affordable. In this case it was a win win. The equivalent electricity price for a heat pump is:

Gas price x HP COP / Gas boiler efficiency

In my case it was 6.2 x 3.6 / 0.9 = 24.8p

Which was 24.8p. On Agile that was basically any time of day apart from the 4-7pm peak.

Bruce

I've just seen that Scottish Power have dropped their SEG rates from 12p to 6p. With more solar farms coming on line and especially the huge Botley West scheme then SEG rates will come under pressure and perhaps a drift towards time of use rates with higher values during the evening peak which will favour west-facing panels.

https://www.bbc.com/news/articles/clyj42pd15go

Peter

Thanks for sharing this ​@Peter E! 

What’s your take on the scale of the project? 

At 840MW it is massive and there have been protests over the size of the scheme but here is my personal take on it.

For the first time in thousands of years the area will be the sole domain of wildlife. No people, no cows, no sheep no yearly ploughing of the land, no nitrate fertilizers or nitrate run off into rivers, pesticide, herbicides or destruction of wild flowers. Other schemes have reported a huge increase in wild plants, insects, birds and a refuge for larger animals. It's big enough for a mini ecosystem with wildlife corridors where small animals could live out their entire lives without being aware of the boundaries. And it generates carbon free power. This maybe the change that partly reverses wildlife decline. The negative is that it will tend to reduce the SEG rate.

Even though I don't have solar panels I benefit greatly from solar power production particularly when there is a bit of wind blowing 

This is an extreme example but most days now I'm seeing a large dip in prices in the afternoon during the week which didn't happen so much last year. The downside is the 4-7pm peak and you have to keep your eye on prices and winter rates can be eye-wateringly high.

Peter 

Morning ​@Peter E, 

It's an enormous project, and I understand why people are hesitant; change can be a scary thought. I wonder what was said when the first wind farms were built—now they're just a part of our lives. Perhaps we could combine the solar panel farm's implementation with the establishment of an official wildlife sanctuary to protect the ecosystem. It would be amazing to see a population boom in small animals, especially since we've increasingly encroached on their land, leading to a decline in some species, as you've rightly pointed out.

The inherent volatility of flexible pricing is such that comfortable rates can rapidly become prohibitive if one isn't vigilant. Is it possible to configure alerts, for example, "prices increasing by XX," to provide advance warning, or does it necessitate constant monitoring?

There’s a lot of it about - new planned solar installations (they are by no means farms) are the current ‘comming thing’; as of course is local protest against them.

https://www.bbc.co.uk/news/articles/cp91yvpvlr7o

I have to say it does seem to make less sense up here in Cumbria, wind turbines are better suited and we have plenty of those already, such as Robbin Rigg in the Solway.
https://en.wikipedia.org/wiki/Robin_Rigg_Wind_Farm
There is also plenty of onshore wind generation too, but that tends to be smaller less visible sites.

For the last 2-weeks while the South has had a heatwave, here in NW Cumbria we have had almost constant cloud cover, rain, and the occasional thunderstorm.
And yes; lots of wind.

​@Chris_OVO and ​@Nukecad there is a place for appropriate schemes wherever you are. On the train down to Exeter from Salisbury you pass Crewkerne where there are acres and acres of solar panels, the ones at the bottom near the line stand in water where there could be no other use for the ‘land’.

As for getting alerts, this is already possible with wholesale ‘day ahead’ (Agile) prices where the price is already fixed 24 hours in advance so with something like Home Assistant reading these prices you can schedule power use / storage at very low rates without any manual intervention. Automation is the key to flexible power use. You can also get predictions for solar and wind generation so you can get even more advance notice of when rates are likely to be favourable.

Coming on line soon and phased over the next year or two is the Dogger Bank A, B and C wind farms rated at a total of 3.6GW. That will create an even bigger and sustained hole in the rates.

I'll provide a link to the various resources that I use when I get back. Assuming I get back. The French Air Traffic Controllers have gone on strike today for our return flight < sigh>

Peter 

Hey ​@Peter E & ​@Nukecad, 

Some tech works better in certain places. Think solar panels in Glasgow – not much sun there, but wind power? Huge potential! I'm guessing these location factors are a big deal when they're planning where to put turbines or panels.

Near me, about a 25-minute drive, is the awesome Whitelee Windfarm. I think what they've done there is pretty smart. They've got a visitor center and tons of walking and cycling paths that go right around and through all 215 turbines. It's cool because you can get some exercise, see the turbines up close, and learn how they fit into the energy system. Plus, they've got the UK's biggest Battery Energy Storage System (BESS) there, which is seriously impressive.

​@Chris_OVO surprisingly solar panels work well in Scotland even though you are a few degrees north than me on the south coast and the east coast is a lot better than the west because of cloud cover and you have a surpising advantage.

If you have bi-facial vertical panels aligned north-south then you will capture the early morning and evening peaks when a time of use SEG will give you a higher rate without resorting to batteries. Batteries don't really help a financial case. Midday solar production will eventually have much lower rates because everyone is in on that game, especially solar farms. The trick is to join the part of the market with fewer competitors. In other words, being agile / adaptive when other people / companies aren't. In the land of thistles and kilts (not a good combination imo) you have very early morning and very late evening sun in the summer at low angles which vertical panels will capture well. You can also mount single sided panels on the walls of your house instead of the roof.

Peter

Despite the French ATC strike Jet2 got us back home from Madeira by avoiding French ATC controlled airspace by flying back north over the Atlantic/Cornwall/Devon/Dorset and avoiding Spain and the Channel whereas Ryanair and easyJet cancelled their flights. Thank you Jet2 (other airlines are available but may leave you stranded).

I'm back here to give you some links to some web pages I find useful.

Watt-Logic: Basically a running commentary on power generation and supply and how the government / Ofgem are failing customers by not regulating the industry properly. People think high prices are related to high gas prices but it's not so. High prices are related to Net Zero costs and the rush that the UK has has in reducing fossil fuel use. Obviously this is not a bad idea but in the UK we seem to be thrashing the poorest because those with money can afford EVs / Heat Pumps / Solar Panels and can get much better deals. Also has a commentary on the Spanish power failure and recently the Heathrow power failure and why it could affect all of us.

https://watt-logic.com/

GB Renewables Map:

Just info on where wind renewables are being generated. From a Net Zero perspective go and click on a windfarm north of the Scottish border and look for any ‘sand’ coloured sections. That is curtailment. There are not enough power links to England (yet) to transmit the power from where it is generated to where it can be used so the excess power has to be curtailed which is logical. The problem with that is that we all have to pay for the curtailment under Net Zero. So not only do we pay more because the electricity would have been cheaper we also have to pay yet more because the windfarms are contracted to be paid for not generating it.

https://renewables-map.robinhawkes.com/#4.96/53.43/-1.11

When Dogger Bank comes on with 3.6GW of power over the next two years it could reduce prices because they do have an adequate connection to the grid. It might not because gas sets the marginal price for anyone not on wholesale or tracker pricing even if the renewables generation price is zero or negative.

Solar output forecast from Terravolt (via Sheffield University):

There is about 16GW of solar power installed and about 12GW max is available on any particular day. About 8GW is solar farms and 4GW from domestic rooftops. If I'm looking to charge my EV on wholesale I can look to see if there is a lot of solar coming up in the next 48 hours. If there is and the car is at home during the day then prices are likely to drop to a low value from 11am to 4pm on a weekday or zero to negative values on a weekend. Sometimes data is not available so I go with my normal 24hr advance prices instead. When we have wind as well then prices can be zero during a weekday.

https://terravolt.co.uk/uk-grid/forecasts/solar/solar-output-forecasts/