Our quest for Net Zero one year on

NedS

Hi all,

It's been (almost) a year since we upgraded our solar install and added the Powerwall 3 battery, and the numbers are in for June so I thought I'd take a look at our numbers for the first year. The PW3 was actually commissioned on the 11th July 2025, so we are not quite a full year and the full 365 day numbers can only improve.

For reference, we replaced an oil boiler consuming around 1600L of oil per year with an ASHP in 2024, so we are an almost fully electric household (still have 47kg propane cylinder for gas top cooking and an oil burner car)

The numbers for July 2025 - June 2026:

Electricity Consumed: 6,596 kWh

Electricity Generated: 7,129 kWh

Total cost (inc standing charges): -£3.49

I am delighted that we are now generating more than we consume on an annual basis, and have managed to just scrape home with a negative bill for the rolling 12 month period including standing charges. The costs would have been better if not for the fact we were late joining the Intelligent Octopus Flux (IOF) tariff last July and were unable to join IOF again this spring as the tariff was suspended in March, which I estimate may have cost us around £200 to £300 in lost export (although we have now been able to join the regular Flux tariff).

For reference, in 2023 before the start of our transformations, we spent £1760 on electricity and around £1250 on heating oil, so around £3,000 per year, and that figure may have been significantly higher this year with the price of heating oil going up 2-3 fold due to the war in Iran.

The heat pump has been exceptional in providing constant comfortable heat and has massively reduced our heating costs, but the real success comes from combining electrification of heating, solar panels and battery storage with innovative smart tariffs from Octopus. This is very much a case of the sum being more than the parts.

So we are net zero, both in terms of our generation/consumption and in terms of cost. Whether we are able to remain net zero (or negative) in terms of cost will largely depend on available tariffs as we are reliant on making enough from export in the summer to cover our bills in winter.

So what's next? We are almost maxed out on the amount of solar we can install, although I do have an E/W shed roof I could potentially put 4-6 panels on once plugin solar is approved. The next logical step for us would be an EV, although I'm still unsure about this. Not so much about the technology, but we've really been struggling to find a suitable EV that offers the flexibility with have with our current car (Skoda Octavia estate). Interestingly, there are rumours that Skoda will release a new from the ground up all electric Octavia in 2028 so that may be the point we make the move to an EV. We do relatively low mileage (~8,000 miles per year) so I'm confident that we may be able to bring an EV onboard and at least partially cover usage with our current excess generation.

For various reasons I won't go into here, we are unable to replace the 47kg propane cylinder for cooking with an induction hob but that 47kg cylinder does last us around 24 months.

Exodi

Very interesting, thanks for taking the time to share!

If you don't mind me asking, what was the cost of the solar install incl battery and what part of the country are you based in?

NedS

We paid £12,250 for the PW3 battery and gateway + 8 panels (3.6kWp) in South Wales (we already had an existing 3.6kWp array). We went with a trusted local company and this was maybe a little higher than we could have got elsewhere but felt it was worth paying the extra to support a local company and get that local support. They did reduce their price slightly to try to help price match, and we probably could have come in around £11,500 from a national company at the time.

Overall I was extremely satisfied with the install and attention to detail we received from the local company who did our install.

sheenas

I guess those in the South West have the most to gain as there is little in the way of gas supply and heating oil is expensive. That makes solar and batteries attractive options combined with a heat pump. The downside is the cost which is likely to be in the 20K bracket depending on your requirements.

Here in Glasgow we are on the gas supply and i don't see any benefit in getting a heat pump. DIY solar is on the cards. A basic system is around £1500 and will provide a battery and panels. If you have a flat roof or garden area for the panels you won't need scaffolding (a big saving). I see it as saving a huge chunk of money on the electricity bill, which is 2/3 of my energy cost. Looking at the numbers my bill could be £800 a year gas and electricity. That is about £400 a year saving.

I think you can over invest on these things for causes that I am not sure are really in the national interest. That is my view anyway.

NedS

https://forums.moneysavingexpert.com/discussion/comment/82056002#Comment_82056002

That's not always the case. For the last 20 years, kerosene has often worked out similar to mains gas much of the time, although there have been instances where the price has shot up due to supply market shocks. 60p/L for kerosene works out at around 5.8p/kWh which is broadly equivalent to gas prices.

My first year of running the heat pump (without batteries to load shift) cost around £450 in electricity (~2300kWh generating 9800kWh of heat). For comparison, gas prices were around 6.5p per kWh that winter (and oil was similar), so would have come in around £700 assuming a 90% efficient gas boiler to deliver the same amount of heat. Our average import prices have fallen from around 20p/kWh in that first winter to 13p/kWh last winter due to the addition of the battery, and increased winter solar output has helped further, all of which we are able to self consume in winter.

Screwdriva

These are the sorts of outcomes I like to see! A clear win for the wallet, the environment and the nation.

I'm glad the price match worked in your favour :)

enthusiasticsaver

Very interesting. We have recently had 21 solar panels and a Tesla Powerwall 3 and EV charger installed and they have only just come into commission a few days ago. We are at the moment waiting on our paperwork so we can export and we are with Octopus too so will be looking either at Octopus Flux or Intelligent Go tariff. So no electricity used at all this week from the grid but we are exporting for free until we get our export paperwork sorted. I hope that is soon as currently we are generating around 38kwh per day in this lovely weather but only using 13kwh

We do not have a heat pump or an EV yet but the EV will probably come first, maybe 2 EVs as both DH and I have cars. DD is charging her car at ours for now as she has an EV.

NedS

https://forums.moneysavingexpert.com/discussion/comment/82056231#Comment_82056231

That sounds great.

Make sure you keep on top of the process with reminders or nudges to get the export approved. You will need your MCS certificate number from your installer and DNO letter confirming approval for connection to the grid. You'll also need an MPAN number assigned for your smart meter, and then once all that is in place, Octopus may need a gentle nudge to get it all activated once you have everything in place. I think mine took around 3 weeks, but a couple weeks of that was wasted waiting for the DNO letter which I resolved with a simple phone call to the DNO in the end and the letter arrived by email shortly after.

Check out Tim and Kat's excellent solar tariff optimiser app online (and their excellent YouTube channel), which is great for figuring out which tariff is best for you. You hopefully already have a good idea of your monthly usage, and you can use reliable monthly estimates of your solar generation using the PVGIS predictor tool.

https://timandkatsgreenwalk.co.uk/

https://re.jrc.ec.europa.eu/pvg_tools/en/

If you are a net exporter (in summer), Flux or Intelligent Flux are hard to beat, but some winter when you are able to use much of your generation, and EVs are importing, a cheap overnight EV tariff may be better (but Tim and Kat's tool above will break all of that down for you on a monthly basis)

silverwhistle

Here in Glasgow we are on the gas supply and i don't see any benefit in getting a heat pump.

So are we here in the deep south, but I hope to get an A2A heat pump, although not this summer as the F-Gas engineers are all a bit busy.. It would provide both heat and cooling, and as a low user of gas the standing charge is painful and from the beginning of May (well, the 10th this year) to October my bill is all standing charge. I'm still building up credit at £70 a month for a 3 bedroom place with PV but no house battery, and including my EV motoring.

Why do you not think this is in the national interest? Burning stuff is inherently inefficient let alone the effort of getting it out of the ground and transporting it. We used 680Twh of gas last year (well down over the last few years) and around 50 Twh was the cost of moving it around our network.

FFHillbilly

sounds good, well done.

An EV makes a lot of sense when you have solar and batteries, its the next logical step I think. especially with V2G around the corner

Jemma01

Thanks for sharing, rather promising progress.

So in total (solar penels + ashp) how much money have you invested? And a year later, how much of that investment have you been able to recoup?

I know you mentioned the cost of SV, but not the cost of total changes.