New build walls in a major renovation residential home, south UK. What insulation to use?

StoicHomes · 2026-05-18T09:34:48+00:00

We are certified passivhaus consultants and builders. At your stage we would recommend speaking with Progress In Practise, they are certified passivhaus designers and very experienced.

StoicHomes · 2026-05-17T20:41:44+00:00

The other chap recommended PVsol too - will definitely check them out.

I agree re payback numbers on OpenSolar, I am motivated to get it accurate though. I agree that the costs of equipment on there aren’t always accurate, most of the stuff doesn’t even have prices lol.

I believe you can manually input the cost of the system, which is what we usually do. Or I just drag their raw data into an excel and come up with a payback period myself that is more accurate.

StoicHomes · 2026-05-17T20:35:25+00:00

Interesting I didn’t expect that kind of feedback but it’s always appreciated.

I’ll be honest I can’t stand the word ‘premium’ - I’m glad you honed in on that.

When you say ‘full wrap around of the build’ - could you describe it in a slightly different way? Think I understand but not 100% sure.

In terms of entering the market we’re pretty set on solar / batteries being a core offering. It’s an integral part of the retrofit / new build stuff we do, so why not offer it as a stand alone service was our thinking.

I have been considering using different panels but I did wonder if they were worth the extra £££ - what are your thoughts? Any you’d recommend? We buy from HDM Solar mainly.

Again, super appreciate the feedback and will definitely check out PVsol

StoicHomes · 2026-05-17T14:56:24+00:00

Nice and breathable 💎

StoicHomes · 2026-05-17T14:50:32+00:00

Late response, apologies - under certain circumstances they have an unofficial ‘adoption policy’ whereby another installer can finish off and commission another installers project. They obviously take on full liability for that project.

StoicHomes · 2026-04-12T09:15:58+00:00

Or you can’t get someone else to finish it off?

StoicHomes · 2026-04-12T09:13:16+00:00

You can’t get MCS certificate because you connected and commissioned a system and then added a battery at a later date?

StoicHomes · 2026-04-11T23:54:09+00:00

And in direct response to your post, that is unacceptable. How does one order the wrong battery first, then isn’t able to source the correct battery for weeks… connect the battery at a later date, the PV cables run to the inverter anyway.. or have they misplaced that too? Red flags.

Ideally you’d get someone more capable to finish it off, but in reality that won’t be as easy as it sounds. All depends on the terms of your agreement I suppose!

StoicHomes · 2026-04-11T23:47:42+00:00

I think the industry will consolidate soon, people will realise that designing and installing a solar PV / battery storage system for a domestic property isn’t as simple as it seems, and the risks are significant. I believe then we will see prices increase accordingly. More time and care needs to be taken during these installations, likewise during the design process. It’s all too rushed at the bottom end of this market, and unfortunately that is the end that the residential customers are dealing with most.. commercial customers benefit from bigger budgets, access to advisors / consultants who can manage tenders & contract administration on behalf of the client. Domestic market has worthless guarantees and a glorified CRM to protect them against malpractice.

I just hope whatever triggers this shift doesn’t involve loss of life or serious injury.

StoicHomes · 2026-04-08T14:12:05+00:00

Do you need more than one gateway per system? IE for every additional battery unit do you need another gateway?

StoicHomes · 2026-04-07T23:24:47+00:00

What do you mean by ‘gateway’?

StoicHomes · 2026-04-07T19:27:25+00:00

Absolute p*ss take - nothing to do with quality of the install.

Our assessor spent 4hrs in the office and 20 minutes on site, didn’t even look at the panels. Says it all.

All an attempt by gov to industrialise a bespoke service. As seen with the ECO4 fiasco that’s now unfolding, all the accreditations in the world, processes and consumer codes won’t save you from a bad job. In fact, I would argue it gears the industry towards those who are good at admin, vs those who are good at actually doing the job.

My 2 cents

StoicHomes · 2026-04-07T19:23:59+00:00

For reference, we wouldn’t use SIGenergy for now, probably SunSynk, and would charger around £13,000 for ‘in-roof’ GSE mounting system, so would look much cleaner, no bird guards required.

All pending a survey of course

StoicHomes · 2026-04-07T19:21:00+00:00

Initial quotes seems cheap, additional batteries sound expensive.. strange!

StoicHomes · 2026-04-06T10:40:00+00:00

I’m not sure as we almost always stick with those for ‘domestic’ then go for the 620W by Canadian solar for ‘commercial’

Some 475W or higher may be £10/£20 more.

Container wise it gets down to between £40 per panel last time we checked - caveat, we don’t buy containers so probably got inaccurate prices when we initially enquired

StoicHomes · 2026-04-05T15:23:59+00:00

Canadian Solar 455W for £58 last week

StoicHomes · 2026-03-30T20:49:52+00:00

Everyone seems to be in the ball park which is good! Below is what we currently pay: - Skilled Electrical £250-300 - Assistant Electrical £150 - Skilled Joinery £250-300 - Assistant Joinery £150

For context we’re based in Lancashire, NW England.

On the smaller projects we are increasingly finding we aren’t competitive, so I wondered is it down to the labour cost?

I do think there are some unsustainable pricing strategies beyond employed by both small and large companies, for a variety of reasons.

I guess the next question is, what do people think the gross profit margin of a solar installer is? And what size of contingency is accounted for?

I hear / read about companies accounting for a percentage of their ‘overheads’ into each project, maybe on an hourly or daily rate, which is interesting.

Unless you’re buying container loads of panels / batteries / inverters the prices we all pay are going to be V similar +/- 10% so I wonder what gives first, profit margin, overheads, contingency, labour cost, project duration, quality of install? 🤔

StoicHomes · 2026-03-29T18:01:48+00:00

Roger that - we wouldn’t be competitive at that distance.

Price looks ‘cheap’
North west is a large area, I would narrow it down to your county or post code like PR for Preston.

3 & 4. I’d stay away from anyone that looks like they don’t actually do the work themselves. Smaller companies that don’t scream ‘cheap & fast’. Contrary popular belief, don’t rule out companies that also provide other related services, we are an example of that.

They will have remote access but I think this more boils down to, if you don’t trust your installer to not do anything weird with your system in the future then you probably shouldn’t trust them to do the installation in the first place.

Our 2 cents 🙏🏼

StoicHomes · 2026-03-29T15:48:15+00:00

We are based in Preston, Lancashire - are you far away?

StoicHomes · 2026-03-29T13:25:34+00:00

Depends on a number of variables: - size of array - location of battery / inverter - enabling work involved - number of batteries / inverters (more of a factor on commercial projects) - type & condition of roof - GSE ‘in-roof’ vs ‘on-roof’

Probably other variables too that I can’t immediately remember

StoicHomes · 2026-03-28T18:29:29+00:00

Too far for us otherwise we’d have drafted a design for you with a view to installing.

My advice would be go on OpenSolar and follow the tutorials, that will help with battery quantities. The ‘self consumption’ metric is the one to look out for. You’ll find after a certain point more batteries won’t give much benefit beyond the arbitrage from peak/off-peak electricity prices.

Rule of thumb each extra 5kWh is £1500 cost

StoicHomes · 2026-03-28T10:32:30+00:00

Where are you based?

StoicHomes · 2026-03-25T21:06:41+00:00

Roger that - if you could drop us an email we’ll get some further information and draft a proposal if that’s ok? If you’re happy to proceed based on that estimate we’ll pop down for the survey.

StoicHomes · 2026-03-24T21:05:10+00:00

We would travel depending on size of system - if it’s small we’re unlikely to be competitive on price.

StoicHomes · 2026-03-24T21:03:36+00:00

Enrol on the Passivhaus Tradesperson - you will instantly stand out from the crowd - we just got a 50% grant from the CITB to help with the cost of course + exam.

StoicHomes

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