In-roof Solar Panels - Self Build House

[Conor]

6 minutes ago, JohnMo said:

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

PowerNI... So probably no use to you.

[JohnMo]

Thanks, as you say no use to me.

[Carrerahill]

On 01/06/2023 at 09:59, iMCaan said:

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

 

Go and build a system up yourself at Midsummer Wholesale and just get an idea of what the costs are. Or Solar Sparky - I think it is high. I think the survey should be excluded for an install that goes ahead, so should admin.

 

 

[S2D2]

5 hours ago, PhilT said:

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...

Just in case anyone is doing these sums, I'm not sure I agree with the logic here. You have to have a battery to be on Flux, so your next best bet without a battery would be Octopus Outgoing at 15p/kWh. That means every bit of export is worth 8p more, regardless of inefficiencies. This is the "worst case" benefit - as if you bought the battery but aren't actually using it other than for the higher daytime export rate.

 

Based on your 23p export you look to be in Eastern England so are paying 34p for import. You would actually charge your battery in the cheap period 2-5am, so for 20.4p, or 22.7p after 10% losses. Everything you import to battery to offset usage (outside of PV generation) therefore saves you 11.3p. This is better, but not a likely use case for summertime Flux, as there is plenty PV to charge the battery without taking from the grid.

 

Therefore in summer, your usage for the battery is shifting from daytime export (which without the battery is 15p/kWh) to the peak Flux export window, 36.6p for Eastern England. For each kWh you shift you gain (36.6 - 15) = 21.6p - by far the best return on battery usage. As an added benefit, you also get +21.6p for any generation in this window, but again you have to have the battery to be on Flux. This is what I believe to be the intended use case for Flux, Octopus are running an experiment where you are paid to load shift the National Grid a tiny bit with your battery, and so pay you a higher export rate for that service.

 

I'm not arguing that batteries are green, or worth investing in for Flux alone which can disappear at any time (it's a flexible rate tariff and Agile Outgoing is already averaging about 9p/kWh) - I just wanted to highlight the sums are a little more complex, 8p/kWh is a long way from 21.6p/kWh, the actual value will depend on your individual usage and lie somewhere between the two (in Eastern England, other regions have slightly different rates). Winter is also a very different story due to the peak import window, I haven't done the sums on this but I don't think Flux will stack up well for winter when options like Cosy exist.

 

I'm also a firm believer that installers are oversizing batteries from a ROI perspective and consumers shouldn't be dragged in to this when a small battery will gain 90% of the ROI benefit. Mine is 2.8kWh usable capacity.

[DougMLancs]

Octopus don’t check for battery ownership when you sign up to Flux at the moment though and the final T&C’s that you sign don’t stipulate a battery. They do say it’s ‘designed’ for solar and battery owners and I think on one of the pages it includes a battery in ‘what you’ll need’. There are plenty of battery-less but happy Flux customers on the MSE Green & Ethical Board. I wouldn’t be surprised if Octopus tightened up on this however.

[PhilT]

On 02/06/2023 at 20:28, DougMLancs said:

There are plenty of battery-less but happy Flux customers on the MSE Green & Ethical Board

🤢wish I was one of them. The only upside now is the possibility of keeping two fridge freezers and one chest freezer full of food from going off, and some lights on, in a (hopefully unlikely) power cut

[PhilT]

On 02/06/2023 at 20:12, S2D2 said:

Just in case anyone is doing these sums, I'm not sure I agree with the logic here. You have to have a battery to be on Flux, so your next best bet without a battery would be Octopus Outgoing at 15p/kWh. That means every bit of export is worth 8p more, regardless of inefficiencies. This is the "worst case" benefit - as if you bought the battery but aren't actually using it other than for the higher daytime export rate.

 

Based on your 23p export you look to be in Eastern England so are paying 34p for import. You would actually charge your battery in the cheap period 2-5am, so for 20.4p, or 22.7p after 10% losses. Everything you import to battery to offset usage (outside of PV generation) therefore saves you 11.3p. This is better, but not a likely use case for summertime Flux, as there is plenty PV to charge the battery without taking from the grid.

 

Therefore in summer, your usage for the battery is shifting from daytime export (which without the battery is 15p/kWh) to the peak Flux export window, 36.6p for Eastern England. For each kWh you shift you gain (36.6 - 15) = 21.6p - by far the best return on battery usage. As an added benefit, you also get +21.6p for any generation in this window, but again you have to have the battery to be on Flux. This is what I believe to be the intended use case for Flux, Octopus are running an experiment where you are paid to load shift the National Grid a tiny bit with your battery, and so pay you a higher export rate for that service.

 

I'm not arguing that batteries are green, or worth investing in for Flux alone which can disappear at any time (it's a flexible rate tariff and Agile Outgoing is already averaging about 9p/kWh) - I just wanted to highlight the sums are a little more complex, 8p/kWh is a long way from 21.6p/kWh, the actual value will depend on your individual usage and lie somewhere between the two (in Eastern England, other regions have slightly different rates). Winter is also a very different story due to the peak import window, I haven't done the sums on this but I don't think Flux will stack up well for winter when options like Cosy exist.

 

I'm also a firm believer that installers are oversizing batteries from a ROI perspective and consumers shouldn't be dragged in to this when a small battery will gain 90% of the ROI benefit. Mine is 2.8kWh usable capacity.

Largely agreed. Keep the decision about the battery entirely separate from the PVs and don't just accept it because it's part a commercial supplier quote because it's unlikely to be financially justifiable. Even "by far the best return" 21.6p/kWh comes nowhere near. With interest rates so high, perhaps a better use for one's hard earned cash would be a 10 year fixed term savings deposit. Unlike heat pumps and solar panels, batteries have little altruistic value except perhaps, as you say, grid load shift support. 

[Dave Jones]

4 hours ago, PhilT said:

Largely agreed. Keep the decision about the battery entirely separate from the PVs and don't just accept it because it's part a commercial supplier quote because it's unlikely to be financially justifiable. Even "by far the best return" 21.6p/kWh comes nowhere near. With interest rates so high, perhaps a better use for one's hard earned cash would be a 10 year fixed term savings deposit. Unlike heat pumps and solar panels, batteries have little altruistic value except perhaps, as you say, grid load shift support. 

 

disagree

 

our battery works great. Value is subjective. a 4k kitchen functions just as well as a 40k kitchen etc

[PhilT]

1 hour ago, Dave Jones said:

 

disagree

 

our battery works great. Value is subjective. a 4k kitchen functions just as well as a 40k kitchen etc

Not sure what you are disagreeing with. My battery works great too but with export rates so high, it currently makes no financial return on a commercial price of around £3k for a 3kWh battery and inverter, but if you can get one for a lot less then well done and good luck, and it could all change of course.

[SteamyTea]

1 hour ago, PhilT said:

3 hours ago, Dave Jones said:

 

disagree

 

our battery works great. Value is subjective. a 4k kitchen functions just as well as a 40k kitchen etc

Expand  

Not sure what you are disagreeing with

Dave like to disagree on most things.

You want 200lt of hot water at 40⁰C, you will be told that you are wrong and need 500lt at 60⁰C.

You want a small car that does 70 MPG, you will be told that they don't exist.

Post up some data, you will be told it is lala land statistics.

Ask to see his data, or calculations, you get no response, because there isn't any.

[iMCaan]

Apologies for late reply, had some build issues. 

 

Thank you all for your comments.

 

I have contacted some MCS approved installers for installation and commissioning price.

Also, I've contacted some sparky's for first and second fix electrics. I have asked some of them whether they can install and commission solar panel system.

 

No doubt buying the panels from Midsummer are a lot cheaper.

It'll be interested to see the price difference (installation and commissioning only) between MCS approved and sparky electricalcompetentperson.co.uk.

 

[Dillsue]

16 minutes ago, iMCaan said:

It'll be interested to see the price difference (installation and commissioning only) between MCS approved and sparky electricalcompetentperson.co.uk.

Not sure you'll get an MCS contractor to provide labour only?? To certify a system they have to install MCS approved kit which they can't gurantee if someone else has provided the kit. See how you get on

[TonyT]

Go the DC route and forget about MCS

[JohnMo]

City plumbing is also competitive with most pricing. Shop around for pricing.

[Dave Jones]

mcs waste of time for solar, leave them to ripoff the heat pump installs.

 

the inroof micro inverters are very good, a little more expensive but better features. they fit underneath the panels so you only end up with a single cable entering the loft.

[iMCaan]

Thanks all.

 

I've had a £16.3k quote from a MCS contractor for 16 x Trina Vertex S 425W system. Their quote includes an itemised pricing and schematic diagram. I've found mostly all items on Midsummer. I've compared the Midsummer retail prices with the MCS contractor prices and the MCS has put a 20% margin on top of Midsummer prices (retail price not trade). I'm sure CMS contractor is buying at trade prices so they will be getting at least 10% trade discount.

I asked him about installation and commission only (£1500 quoted) but he said they do but they don't put a priority on that as it’s usually not worth it for them. I think it was his way of telling me "no".

 

An online store (Solar Energy Store) have quoted just under £9k (13 (according them 16 panels won't fit on my house roof) x Jinko Tiger Solar 430W ) for in-roof system plus £2500 for installation and commissioning.

They are offering MCS certification for £500 if I self install the system.

 

Still waiting to find a sparky (non MCS contractor) who can install and commission the solar system.

 

 

[iMCaan]

An update...

 

I met couple of qualified electricians to discuss wiring the house. Both have not installed or wired solar panels before. Both electricians are not keen on installing the solar system.

 

Also, I asked them about wiring UFH and both insisted that plumbers do UFH wiring. Is this true?

 

Thanks

[Dave Jones]

23 minutes ago, iMCaan said:

An update...

 

I met couple of qualified electricians to discuss wiring the house. Both have not installed or wired solar panels before. Both electricians are not keen on installing the solar system.

 

Also, I asked them about wiring UFH and both insisted that plumbers do UFH wiring. Is this true?

 

Thanks

 

couple clowns by the sound of it.

 

solar is a single 240v cable they need to terminate in a board. even the thickest sparky should be able to manage that.

 

UFH wiring, assume you are looking at room stats ? they are a bad idea as you dont want zones as it kills efficiency. makes the install much simpler/cheaper.

 

 

[JohnMo]

I started and paid to install 6 zones, not knowing much better at the time.  All hard wired to an UFH wiring centre. None are now used, were just a waste of time and money, really not good enough for UFH. Now have a single 0.1 deg hysterisis wireless thermostat controlling an ASHP directly for overheat protection. UFH wiring centre not used anymore, as UFH manifold is directly pumped from ASHP also.

 

keep it simple.

[iMCaan]

Thanks but I'm not sure I completely understand when you say keep it simple. 

 

Do you mean there are fewer thermostats (e.g. one thermostat per room?)? And that the wiring centre is wired such that it controls all pipe loops in a room at once?

 

In some rooms, there are more than one pipe loop. Does it mean that I need to put one single pipe loop per room?

 

How would you simplify the attached design, in particular the open plan L shaped room? Should it have one or 3 thermostats and how many pipe loops?

 

Wunda have suggested two manifolds per floor (GF 7 & 10, FF 5 and 10). Does simplifying mean we can have fewer port manifolds?

 

As part of simplifying are self regulating actuator valves required?

 

I have already asked them not to include smart hub & boiler switchs, mart connection box and wundaSmart square thermostat with probe.

 

We will have a gas boiler and water cylinder to feed the UFH.

 

Thanks

 

[JohnMo]

1 hour ago, iMCaan said:

Do you mean there are fewer thermostats

One thermostat per floor. 

 

Would review your need for UFH heating upstairs?

1 hour ago, iMCaan said:

Does

 

1 hour ago, iMCaan said:

In some rooms, there are more than one pipe loop. Does it mean that I need to put one single pipe loop per room?

 

No, you are restricted by max allowable pipe length.

 

1 hour ago, iMCaan said:

 

As part of simplifying are self regulating actuator valves required

No not really, I had them removed them, they brought nothing to the party.

 

1 hour ago, iMCaan said:

How would you simplify the attached design, in particular the open plan L shaped room? Should it have one or 3 thermostats and how many pipe loops?

I would delete all hallway loops, and just spread the pipes already going through those areas.

 

What are you pipe centres and what is your heat demand in kW?

[iMCaan]

Thanks @JohnMo 

Pipe centres: 150mm

Estimated UFH project loading in KW : 21.56kW

 

Where will the one thermostat be placed, near the staircase?

 

Thanks

[JohnMo]

52 minutes ago, iMCaan said:

Estimated UFH project loading in KW : 21.56kW

That can't be the heat demand of a new new build house. Mine is 192m2 or 225m2 if I include the plant room and only needs 3.5kW.

 

I would do a wireless thermostat, then you can move to where suits the heating control best. Which you won't know until you have lived in it for a while.

[iMCaan]

It appears Wunda has miscalculated 21.56kW.

 

Robbens Systems have stated

GF Total heat load 5.01 kW

FF Total heat load 6.51 kW

 

Another company as stated Total Heat Load 17412 W

 

It still appears a lot more load than  your house.

 

 

[JohnMo]

Have you actually calculated it yourself, using the spreadsheet in boffins corner.

https://forum.buildhub.org.uk/topic/439-fabric-and-ventilation-heat-loss-calculator/

 

Even at 302m2, 11kW sounds big heat demand.