In-roof Solar Panels - Self Build House

[iMCaan]

Hi

 

So finally (it's taken over a year to get to this stage) we've started to install roof trusses on our self build detached house. I have received three quotes for solar panels all around £13k, two quotes are in-roof installation and one company quoted top-of-roof installation.

The company that quoted top-of-roof installation insisted that in-roof panels would make the roof leak and I should not go with in-roof installation. Whereas the in-roof company said we have to put a good quality breathable membrane, probably double the membrane, so there's no chance of leak. Has anyone had in-roof installation? What are you're thoughts on in-roof installation? Any recommendations or suggestions on in-roof instillation are highly appreciated.

 

The installation will be done in two phases. Phase one, solar panel installation and then on a later date connection to the power grid and house electrics.

 

The following is one of the quotes (in-roof), total cost £12,900. Does this seem like a reasonable quote (based in Leeds)? 

Currently, the roof trusses are being fitted and the scaffolding will be provided.

 

Quote:

 

1 SUPPLY OF PHOTOVOLTAIC SYSTEM (5.92 kWp) £10,530, which includes:
16 JA SOLAR 370W ALL BLACK

2 FOX ESS FOX 2.6KWH BATTERY

1 FOX ESS FOX 5KW

1 EMLITE GENERATION METER

1 CLENERGY RAILING
 

INSTALLATION OF PHOTOVOLTAIC SYSTEM £1,500
SURVEY £220
MISC ELECTRICAL ITEMS £300
REGISTRATION AND CERTIFICATION 150
ADMINISTRATION £200
Sub Total: 2,370

 

Thanks

 

[eandg]

We have in-roof. The panels sit on trays and the roofers flash around them so there's no prospect of any water penetration as long as it's detailed properly. 

 

Looks a wee bit pricy to me, depending on cost of battery (we don't have one). Our quotes were all around 5-6 grand for 4kW system (yours is 5.92). For install, it took three roofers less than two hours from leaving their van to getting back in it - so £1500 is expensive but there's good money to be made in that game. 

[JohnMo]

I would do some maths before you commit.

 

£13 000 quoted. Electric is currently £0.34 per kWh. And going down in price, so payback will be even longer.

 

13 000/ 0.34 = 38 000kWh.  If you you can generate and consume 3800kWh, it will only take 10 years to pay for its self. Likelihood you will have loads of PV electric in the summer, best part of nothing in the winter.  So more like 15 year payback.

[DougMLancs]

That quote seems high- I had 12x JA Solar 370W, a gen 2 3.6kW Givenergy hybrid inverter and a 9.5kW battery done in roof for £9800 in the NW last month. We’re earning roughly £5 a day on flux export at the moment which will build a nice credit balance to pay for the off peak charging in the winter. 

Edited June 1, 2023 by DougMLancs

[PhilT]

One issue is the relative efficiency - most sources say in-roof panels are 5-10% less efficient because on-roof panels have a gap between the panel and roof tiles which allows air to circulate, keeping the panels at a lower temperature

[iMCaan]

 

Thank you all.

It's good to know that in-roof system does work. Mine is a new build so in-roof will look good. Will speak to roofer to see if double felt can be added for piece of mind.

Payback more than 15 years - don't think I will wait that long. I was more thinking around 8 years for the payback.

 

If 5-6 grand for 4kW system - Sounds like I should be able to get around 8kW for 12 grand?

 

 

@DougMLancs One of the company's said that they charge £250 per panel (+ the cost of accessories to go with the 4 panels)so let's say £11,000. If I can get the price dropped to under £12k. I think I may be OK with that? I don't understand  "a gen 2 3.6kW Givenergy hybrid inverter and a 9.5kW battery" whether it's better or similar to what I've been quoted so I've not considered it in £12k.  

Probably, try my haggling skills with the company (the walk away technique usually works). Probably, the rep will do the classic, give his manager a call.

 

Thanks

 

[iMCaan]

18 minutes ago, PhilT said:

One issue is the relative efficiency - most sources say in-roof panels are 5-10% less efficient because on-roof panels have a gap between the panel and roof tiles which allows air to circulate, keeping the panels at a lower temperature

 

Thanks. I think I read that too somewhere. I think I'm ignoring it considering we rarely get high temps, also they'll be outside and higher up.

[JohnMo]

15 minutes ago, iMCaan said:

most sources say in-roof panels are 5-10% less efficient because on-roof panels

Not sure they are correct in the UK, maybe a couple of days a year. There is an independent UK report (tried looking but can't find it) which explored every option over a whole year and little or difference between in and on roof. A roof without insulation behind it was no different, a roof with insulation behind the membrane made about 1-2% for a couple of hours for a couple of days. Basically sun had to be direct on the panel in the height of summer, as soon as the angle changed by a degree or so as the sun moved east to west, it was back to status quo between in and on roof.

 

My roof has insulation behind the breather membrane and on sunny day I still get rated capacity.

[Dillsue]

1 hour ago, iMCaan said:

@DougMLancs One of the company's said that they charge £250 per panel

370 watt panels can be had for half that price retail and likely less for trade. That's a hell of a markup! 

[SteamyTea]

1 hour ago, iMCaan said:

 

Thanks. I think I read that too somewhere. I think I'm ignoring it considering we rarely get high temps, also they'll be outside and higher up.

Yes, best ignored. The confusion comes about because of the testing method. During testing the modules are given a flash of light, at a known intensity and while the modules are at a known temperature.

Those condition will be extremely rare events in the real world.

So rare intact they probably never actually happen.

[DougMLancs]

1 hour ago, iMCaan said:

If 5-6 grand for 4kW system - Sounds like I should be able to get around 8kW for 12 grand?£12k.  

Double the kW definitely shouldn’t be double the price. There are many costs to an installation which are either fixed or change relatively little in proportion to the system size so I would expect an 8kW system with no battery to be no more than £9k and that’s probably still on the steep side.

[iMCaan]

35 minutes ago, Dillsue said:

370 watt panels can be had for half that price retail and likely less for trade. That's a hell of a markup! 

Just done a quick Google search for "JA SOLAR 370W ALL BLACK". They are all around £150inc VAT and I don't think it's trade price (even though website has word "trade" in it), that's 1600 markup. What a rip-off.

[eandg]

If you don't need the MCS for a loan/grant then just buy yourself and find a roofer and spark to do it. I know our supplier just orders there's direct from Midsummer so could see the mark-up but I was getting 25% back and the rest rolled into a loan and it removed a hassle so I took the hit - but otherwise I'd definitely just have ordered direct, from seeing the install there's nothing to it if you have a bit of basic competence. 

[Dave Jones]

3 hours ago, iMCaan said:

 

Thank you all.

It's good to know that in-roof system does work. Mine is a new build so in-roof will look good. Will speak to roofer to see if double felt can be added for piece of mind.

Payback more than 15 years - don't think I will wait that long. I was more thinking around 8 years for the payback.

 

If 5-6 grand for 4kW system - Sounds like I should be able to get around 8kW for 12 grand?

 

 

@DougMLancs One of the company's said that they charge £250 per panel (+ the cost of accessories to go with the 4 panels)so let's say £11,000. If I can get the price dropped to under £12k. I think I may be OK with that? I don't understand  "a gen 2 3.6kW Givenergy hybrid inverter and a 9.5kW battery" whether it's better or similar to what I've been quoted so I've not considered it in £12k.  

Probably, try my haggling skills with the company (the walk away technique usually works). Probably, the rep will do the classic, give his manager a call.

 

Thanks

 

 

dont add double felt, you want the roof to breath. There is no possibility of water ingress with a GSE tray unless the panel is physically removed. depending on what tiles you have I found lead much neater than the galv metal flashing kits as it made our tile sit too high and looked bad. Lead soakers worked perfect.

[Dillsue]

1 hour ago, iMCaan said:

Just done a quick Google search for "JA SOLAR 370W ALL BLACK". They are all around £150inc VAT and I don't think it's trade price (even though website has word "trade" in it), that's 1600 markup. What a rip-off.

There's a seller on ebay got them at £120 with plenty in stock so not a one off deal. I'd imagine trade would be cheaper than that??

[Dave Jones]

3 minutes ago, Dillsue said:

There's a seller on ebay got them at £120 with plenty in stock so not a one off deal. I'd imagine trade would be cheaper than that??

 

the ebay user is almost same as your username here!!!

 

forum discount ?

[Dillsue]

3 hours ago, Dave Jones said:

forum discount ?

You'd have to ask the seller, but they seem at a good price already

[iMCaan]

Thank you all. your comments and suggestions are  really beneficial. Highly appreciated.

 

 

20 hours ago, eandg said:

If you don't need the MCS for a loan/grant then just buy yourself and find a roofer and spark to do it. I know our supplier just orders there's direct from Midsummer so could see the mark-up but I was getting 25% back and the rest rolled into a loan and it removed a hassle so I took the hit - but otherwise I'd definitely just have ordered direct, from seeing the install there's nothing to it if you have a bit of basic competence. 

 

Quick Google search returns "MCS is not a mandatory or legal requirement for system installation".

However, I'm not sure whether the building regs. officer will be OK with it?

 

£120, that's way less than half the price I've been quoted. 

 

I'll try to find a sparky. 

 

@Dave Jones Thanks will use single felt. Will be fitting slates not tiles. Will speak to roofer about lead soakers. 

[PhilT]

On 01/06/2023 at 12:06, iMCaan said:

 

Thanks. I think I read that too somewhere. I think I'm ignoring it considering we rarely get high temps, also they'll be outside and higher up.

One advantage of in-roof is no doves crawling underneath. I have this problem and it's a losing battle - may have to bite the bullett and get some protective mesh at some point.

[Conor]

12 minutes ago, iMCaan said:

Thank you all. your comments and suggestions are  really beneficial. Highly appreciated.

 

 

 

Quick Google search returns "MCS is not a mandatory or legal requirement for system installation".

However, I'm not sure whether the building regs. officer will be OK with it?

 

£120, that's way less than half the price I've been quoted. 

 

I'll try to find a sparky. 

 

@Dave Jones Thanks will use single felt. Will be fitting slates not tiles. Will speak to roofer about lead soakers. 

BC won't care as long as the loadings have been accounted for in the design. Your DNO and electric supplier will, however. The installation will need to be signed off as safe and G98 compliant by a competent spark. But no requirement to be part of any scheme. My 5.2pKw in roof install cost about £5k. That includes the £600 for the sparks side of things. Prices have gone up a bit so im not sure you'll get it done for 1p/W. I installed the trays myself with help of the roofers. Fairly simple once you get your head around the battening requirements.

[DougMLancs]

Bear in mind you won’t be able to get paid for your export if you go the DIY route. This isn’t a dealbreaker with most suppliers paying pittance but Octopus will pay 15p a unit flat rate on their Outgoing Fixed or 21.7p day rate/34.8p peak rate on their Flux tariff. Just something to consider in your calculations.

Edited June 2, 2023 by DougMLancs
Typo

[PhilT]

59 minutes ago, DougMLancs said:

Bear in mind you won’t be able to get paid for your export if you go the DIY route. This isn’t a dealbreaker with most suppliers paying pittance but Octopus will pay 15p a unit flat rate on their Outgoing Fixed or 21.7p day rate/34.8p peak rate on their Flux tariff. Just something to consider in your calculations.

If you go down the MCS/Export route think carefully about whether or not solar battery storage makes sense. Solar storage is not "renewable" or "green", being a net consumer of energy, not to mention the materials and energy used in the making. I have a 3kWh battery, which I could justify with the Cosy tariff, but no longer now I'm on the Flux tariff. I get 23p standard rate for every kWh exported. That means it's costing me 23p/kWh to charge my battery, plus 10% charging loss = 25p/kWh, so I only make (33-25 = ) 8p/kWh saving by using "free" solar energy. Now work out the payback on the cost of your battery...

[Conor]

1 hour ago, DougMLancs said:

Bear in mind you won’t be able to get paid for your export if you go the DIY route. This isn’t a dealbreaker with most suppliers paying pittance but Octopus will pay 15p a unit flat rate on their Outgoing Fixed or 21.7p day rate/34.8p peak rate on their Flux tariff. Just something to consider in your calculations.

Not strictly true. You just need to provide your electric provider with the details they require - schematic, system capacity, details and a safety sign off. I'm getting 8.5p, better than nothing. 

[DougMLancs]

That’s interesting and good that some suppliers are actually taking on non-MCS/flexi-orb installations. Octopus will only take MCS unfortunately for many.

Edited June 2, 2023 by DougMLancs

[JohnMo]

1 hour ago, Conor said:

Not strictly true. You just need to provide your electric provider with the details they require - schematic, system capacity, details and a safety sign off. I'm getting 8.5p, better than nothing. 

Could I ask your supplier please, I may move electric provider if I can get paid.