Electric combi boilers / solar panels / eco heating solutions

^i guess they might be, I have a roof that faces SW.

Thanks for all the answers - sunamp/batteries look good, but they’re expensive and I don’t use that much hot water. Maybe the best solution is just a new, super well insulated, and small cylinder.

There doesn’t seem to be a single obviously better than everything else solution

Just revisiting our options for making use of the boiler upgrade scheme. Our EPC (currently an appalling F) contains a recommendation for cavity wall insulation. We're not sure whether that's "technically feasible", as all recommendations are required to be - see 4.3, since the cavity is only 40-5omm wide and we're in a zone of severe weather exposure.

If we can get that recommendation removed, we can access the boiler upgrade scheme grant. Has anyone had any experience of getting an EPC amended either by contacting the original assessor or via a new assessment?

They seem to want to do it all as they get extra money from every other add on they could get.

My girlfriend is in need of a new boiler, and after a read of here and the grant meaning things likely similarly priced I've suggested a heat pump. After a vague look around would Ovo be the guys to speak to? Heatgeeks directly looks expensive but from what I can tell Ovo use them and the better Vaillant equipment. She'd likely need some new, bigger radiators but the kitchen/diner bit of the house (a B on whatever the assessment thing is but some windows seem leaky to me) doesn't really have room for anything other than the tall but thin thing on one wall, she's not skint but not wanting the traditional £40k forum kitchen either. Any tips? Some kind of assessment would be good but the octopus ones are £500 and haven't got much love in here of late. An easy to guesstimate "what radiators would I need in this room" kinda chart would be helpful.

Heat pump assesment tool heat punk could be used. Or look at current gas usage.

Any old boiler will work, but a heat pump needs to be sized well and commissioned correctly or it won't. And it seems many are fitted by cowboys.
Underside heat pump wont warm house. Overesized will be inefficient running on warmer days that need heating.

I moved my discussion over to here yesterday. https://www.lfgss.com/conversations/144504/?offset=75#comment17304861

Any experience/insights of Aira? Looks like they use Vaillant pumps and free assessments.

Good news for many, they are removing the requirement to have cavity wall and loft insulation to access the heat pump grant
https://www.energylivenews.com/2024/03/14/uk-revamps-heat-pump-grants-scheme/

Solar production is starting to kick up again!

When it stops being so cold at night, should soon start building up credit on the account.

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So good!

Remind us what kind of solar setup you have?

I have 6.6kw of solar panels, split east and west, with a Tesla powerwall.

2 EVs, being charged overnight on the intelligent go 7.5p tariff and being paid 15p export on solar.

We’ve set it up to never charge the battery using solar and to export every Kw to the grid, and the powerwall has enough storage to sort us out through 5am-1am.

I really should switch to the Intelligent tariff myself at some point. At the moment I've got the solar/battery setup operating so that solar energy goes to the house first, then the battery, then the grid, on the Octopus 15p per kWh export tariff. It works well, and last week the export output was enough to cover not only the minimal electricity costs but also the gas bill. But I think it would be financially better to switch to an intelligent tariff, charge the the battery from 1am to 5am on the 7.5p/kWh rate, export the battery contents from 5pm to 7pm when the peak export tariff kicks in, and then not bother using the battery for storing solar.

I should probably also fill the fourth slot in the battery array to take it up to 9.6kWh but that's another thing I probably won't get round to doing for months if not years...

I had considered the agile export, to take advantage of the peak price usually between 5-7, but ended up working out that the 15p flat tariff would probably work out better for us.

Programming the system to export at all solar at 15p and purchasing all electricity at 7.5p is simple and almost as good as a perfectly optimal routine with excess battery being held and dumped at super peak times.

We’ve done some of the octopus saving sessions where they paid a ludicrous £1 a kw for 30m.

Very inspirational, thanks.

Do you have solar export data insights throughout a full year?

Key information for 2023 (6.6kw solar, 13.8kw battery):

Generated 5840kw
Exported 2290kw
Purchased 3596kw
Total electricity consumption 7146kw

Average octopus tracker tariff price was 19.64p/kw with a standing daily charge of 47.5p
Export price was 15p/kw
Purchased electricity - £706.25 + £173 = £879.25
Exported electricity - £343.50
Our electricity bill was £535.75 last year.

If we didn't have solar, our bill would have been £1576.47, so solar has saved us £1040.72.

We spent approx. £17500 on the solar and battery setup so it would take an unimpressive 16.8 years to pay it back. This is partly because of the drop in electricity prices, at the time we were facing 40p/kw or more, at this rate (which will surely happen with inflation going forwards) we would be saving £2323 per year, and solar setup would break even in 7.5 years.

Thats not using the EV fuel savings (the cost of leasing the cars/insurance have remained approx the same when switching from petrol to EV).

We will use approx. 5714kw for charging the EVs (about 20k miles) which will cost us £428 per year.
Equivalent petrol at 150p/l and 40mpg is £2838 per year.
Saving of £2410 per year on fuel.

£3450 saved per year, just over 5y to pay back the system.

As we have changed how the system exports and imports electricity, and have a second EV I expect our usage to look like this:

4500kw home use at 7.5p (charged overnight and used during the day via battery)
5714kw car use at 7.5p
Total: £766.05 + £173 standing charge = £939.05
5800kw solar export export 15p = £870
Electricity + fuel bill of £69 for the year.

No solar EV comparison:
Electricity bill of £1065 (assuming 19.64p/kw)
Petrol bill of £2838
Total bill of £3903 for the year

Saving of £3834 per year

Pay back the system in 4.56y, faster as petrol and energy prices increase over time.
At the time we decided on switching to solar, battery and EV, electricity was 40p/kw and petrol was 180p/l. If it had continued in this way, we would have had the total system paid back in 3.4y.

A big bulk of the benefit is the EV fuel saving, and the battery, which then allows the 7.5p intelligent tariff and usage.
A 10kw battery, say for £5000 installed (currently 0% vat) charging at night, 4000kw annual usage. If you had 1 EV using 2800kw (approx. 10k miles) and you charged at night at 7.5p.
£510 electricity a year.
Compared to 10k in a petrol car, and 4000kw at 19.64p/kw, you would save about £1700 a year, paying back the battery in under 3 years. Without an EV, battery would take 10 years to pay back.

Obviously continued significant savings after that period.

TLDR:

Even though we spent more than needed for the best return on investment, we should pay the system off in under 5 years, and saving ourselves about £3000 a year thereafter.
Buy as much as possible cheap at 7.5p, sell everything you can at 15p or more.
Petrol is expensive.

Thank you for this mouthwateringly detailed post; again, very inspirational.

I'd love to get a leccy car and do the same, alas home charging would be very difficult due to no driveway...

Has anyone heard much from Waltham Forest about 'pavement cable gullies' to enable slinging a charger across the road?

When did batteries get so cheap?
https://www.hotukdeals.com/4334174

Exported 37kWh today. New record.

We’ve exported 883kWh since install on Jan 13th (£132)

We’ve purchased 2.3mWh since Jan 1st (£172)

Not a bad delta considering we run two EVs at around 22,000 annual miles combined.

Genuine question, what’s it cost you to install the setup and what is your payback?

£13k for 18 420W panels (7.5kW total) array, 10kWh battery, 6kWh inverter and install etc.

Buying it now, I’d probably get 50-100% more battery capacity for the same amount as there are some super competitive deals out there.

Using the same man maths as @Acliff in including my EV charging rate overnight, I’m looking at 5 years ish so far.

Good going. I exported 24kWhs today from 16 420W panels, from a total output of 35.7kWhs.

5MWhs generated since June last year.

Thanks. We’ve got 9 panels that are NE and 9 SW facing on either side of our garage so we get a solid profile of generation all day.

Did help that we’re away on holiday so only really using around .28kW at any one time.

This is yesterday:

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Quick fire opinions please.
Which option would you go for?

Option 1
Spend £12k now getting an array of 14 PVs and 2 whopping big batteries now and reduce electricity outlay to nearly nothing.

Risk - We spend ££ then in 6months there is a bang up scheme that would have saved us £8k or something

Or

Option 2
Hold fire and see what Kier and the lads have in store for the 'rooftop revolution' on energy?

Risk - We keep paying unspeakable amounts of money on energy (Approx £260 a month) and burning funds while we wait to see if anything happens and there is also a risk that any grants or schemes will be means tested which we almost certainly won't qualify for.

Wait til the October budget?

I would wait until budget as it's not long in the grand scheme of solar / battery payback timelines.

^this.

Even if measures don't come in immediately you should have an answer within the next 4 months.