12 May - net zero day

[RedRhino]

Well I'm chuffed to bits with the performance of our new self-build house. 

With another 6 weeks to go before mid-year our 2026 electric bill has balanced out. By mid-year we should be in credit by about £150, so maybe £300 for the whole year. 
That is for DHW, heating and domestic load. 2 people in permanent residence, with guests, 200m^2, thermostat set at 21.5c throughout. 

We run a sauna but not an EV.
Contributing factors in approximate order of importance: 

1. High levels of insulation in floor, walls, and roof (MBC high performance timber frame)
2. Very good air tightness (0.8)
3. Large solar array 3kw facing SE and 6kw facing SW with no overshading from trees / chimneys etc
4. Octopus Flux tariff
5. Tesla Powerwall 3 battery
6. 5kW ASHP
7. UFH
8. Triple glazing

 

Each item has value in itself, but they also complement each other e.g. the UFH reduces heating temps which increases the efficiency of the ASHP which reduces demand which . . . 

I just need to tell Octopus that they need to set up a Direct Debit to pay me : ) 

[Alan Ambrose]

Congrats. Also, good to think there’s light at the end of the tunnel. 😀

[SteamyTea]

2 hours ago, RedRhino said:

Well I'm chuffed to bits with the performance of our new self-build house. 

With another 6 weeks to go before mid-year our 2026 electric bill has balanced out

I have not followed your build, but goes to show that it is, I assume, just a case of solid and sensible engineering.

[RedRhino]

Exactly that - just balanced decisions and good execution with the freedom that only new-build gives which is to consider everything in the round. 
For instance, we knew we were having a large solar array from the very beginning, so we told the architect we wanted a rectangular roof to best fit rectangular panels.

[SteamyTea]

2 minutes ago, RedRhino said:

For instance, we knew we were having a large solar array from the very beginning, so we told the architect we wanted a rectangular roof to best fit rectangular panels.

Always narks me a bit when people say that want PV, then don't fit it because of cost. I suspect very few fit it later.

[SimonD]

49 minutes ago, SteamyTea said:

Always narks me a bit when people say that want PV, then don't fit it because of cost. I suspect very few fit it later.

It's a bit like the stream of people who want a heat pump and when you tell them there's an up front charge of a few hundred pounds for a proper heat loss and system design they balk at the idea.

 

 

55 minutes ago, RedRhino said:

For instance, we knew we were having a large solar array from the very beginning, so we told the architect we wanted a rectangular roof to best fit rectangular panels.

Well done you. We have a barrel shaped roof and nobody wants to touch it for solar! We're having to look at alternatives. The roof does look lovely mind 😉

[SteamyTea]

35 minutes ago, SimonD said:

The roof does look lovely mind

Not at night though, and that is quite long in the wintertime.

 

Roof Integrated PV is so unobtrusive, and cheap to fit at build time, I don't understand why it is not done more.  Might be ignorance as a lot of people still think that PV costs many, many thousands.

(When I go and see our old mate Jeremy Harris, I never notice the PV on his roof, and his place is only 1 1/2 the height of a bungalow)

Edited 5 hours ago by SteamyTea

[SimonD]

1 hour ago, SteamyTea said:

I never notice the PV on his roof

 

It's like most things. People walk past solar installs and just accept it's a solar installation. The integrated stuff for our metal standing seem roof simply wasn't available at the time I ordered the roof - I was lucky enough then to get some of the last coils in the UK as we were in the middle of COVID lockdown at the time. However, I've since learned some of these for metal roofs suffer from heat degradation as they're stuck to the metal roof.

[RedRhino]

1 hour ago, SteamyTea said:

Roof Integrated PV is so unobtrusive, and cheap to fit at build time, I don't understand why it is not done more. 

 

Yes - you have to cover the roof in something, why not solar panels? Only retro-fitters fit solar panels on top of roof tiles. 

[-rick-]

2 hours ago, SimonD said:

We have a barrel shaped roof and nobody wants to touch it for solar! We're having to look at alternatives. The roof does look lovely mind 😉

 

*tongue in cheek* That's not the answer I expect from someone who decided there weren't any good heating installers so became one himself. Time to become a 'pv and heatpump' specialist

 

Edited 3 hours ago by -rick-

[SimonD]

37 minutes ago, -rick- said:

 

*tongue in cheek* That's not the answer I expect from someone who decided there weren't any good heating installers so became one himself. Time to become a 'pv and heatpump' specialist

 

OMG! 😁 My wife mentioned this in passing the other day - asking if I shouldn't start doing solar too. I reminded her of the pain of MSC certification for heat pumps, lets do one thing at a time, and she went quiet. But on a more serious note, I have done an initial design for the house which could solve the problem 😊

[SteamyTea]

3 minutes ago, SimonD said:

reminded her of the pain of MSC certification for heat pumps

Was a while back, and things have changed, but when we were doing MCD PV, we got asked to do an ASHP and the MCS paperwork was quite minor as we already had most of it.

[JohnMo]

Well done @RedRhino

 

@SimonD PV vertical panel fence, or ground mount.  Vertical great winter performance at the cost of a small hit in summer in ultimate production, opposite true for ground mount. DIY install, apply for export via octopus - no MCS in site, or needed.

 

Only issue is panels have doubled in cost over the last 3 months. But still cheaper than a fence panel.

[-rick-]

2 minutes ago, JohnMo said:

Only issue is panels have doubled in cost over the last 3 months. But still cheaper than a fence panel.

 

Prices at Bimble Solar don't seem much higher than last time I checked. Guess they have older stock but worth looking at if looking to buy.

[JohnMo]

5 minutes ago, -rick- said:

 

Prices at Bimble Solar don't seem much higher than last time I checked. Guess they have older stock but worth looking at if looking to buy.

That's good to know👍

[SimonD]

20 minutes ago, SteamyTea said:

MCS paperwork was quite minor as we already had most of it.

In the grand scheme of bureaucracies, the actually paperwork for MCS on each job, is probably not that bad, but it does take a few hours to complete. Most of it's done when doing a proper design. But the issue was more the actual process of gaining the MCS certification to begin with and the ongoing required QMS stuff - not designed for small businesses at all.

 

2 minutes ago, JohnMo said:

PV vertical panel fence, or ground mount.  Vertical great winter performance at the cost of a small hit in summer in ultimate production, opposite true for ground mount. DIY install, apply for export via octopus - no MCS in site, or needed.

 

Only issue is panels have doubled in cost over the last 3 months. But still cheaper than a fence panel.

Yes, looked at those. My issue is the permitted development limitations. I keep on getting conflicting information about this. We need to replace our south facing fence, which would give us a stretch of 16m of fence to mount the panels and would be ideal. Some say I need planning, some do not. And our local planning dept don't seem to know what they're talking about as I had one tell me heat pumps can't be installed in conservation areas!

[JohnMo]

6 minutes ago, SimonD said:

16m of fence to mount the panels and would be ideal. Some say I need planning, some do not.

Suppose depends if you call it PV or black glass fence panels. And how you interpret permitted development rules on area for a ground array, is it ground area or panel area. 16m x 35mm isn't much ground area.

 

Do it in bifacial panels, so it looks pretty (black glass) both sides rather than black glass one side and white plastic the other.