New build air source heat pump advise please

Martyn1981

GreatApe wrote: »

Can someone give me some advise on solar for new builds. What is the fit on PV if any on new builds?
I assume it would cost about £4,000 for a 4KWp system the scaffolding is already in place.
How much roof area is needed for 4KWp? Thanks

There used to be a separate new build rate, that was slightly lower than retro-fit, but I think that ended a few years ago, now there's just one rate.

For 4kWp a good price would be £5k, so with scaffolding in place and easy access to the electrics, £4k might be possible with some haggling.

Roof space will depend on the panel types. they are typically 1.6m by 1m, so 1.6m2, but vary from 250Wp to over 300Wp now. Expect reasonable prices up to 290Wp(ish) after which they'll get proportionately more expensive.

Size wise, fit as much as you can, the tariff rate is now 0-10kWp. The only limit will be a DNO restriction (these are the people that run the distribution network, not the National Grid) to an export limit of 3.68kW. You can ask for more, but it will depend on the local infrastructure. For 4-5kWp a 3.68kW capped inverter will be fine, with minimal annual capping. If split, say E/W, then 6kWp might be OK through a single 3.68kW capped inverter.

GreatApe

Martyn1981 wrote: »

There used to be a separate new build rate, that was slightly lower than retro-fit, but I think that ended a few years ago, now there's just one rate.

For 4kWp a good price would be £5k, so with scaffolding in place and easy access to the electrics, £4k might be possible with some haggling.

Roof space will depend on the panel types. they are typically 1.6m by 1m, so 1.6m2, but vary from 250Wp to over 300Wp now. Expect reasonable prices up to 290Wp(ish) after which they'll get proportionately more expensive.

Size wise, fit as much as you can, the tariff rate is now 0-10kWp. The only limit will be a DNO restriction (these are the people that run the distribution network, not the National Grid) to an export limit of 3.68kW. You can ask for more, but it will depend on the local infrastructure. For 4-5kWp a 3.68kW capped inverter will be fine, with minimal annual capping. If split, say E/W, then 6kWp might be OK through a single 3.68kW capped inverter.

Thanks the roof is south by south west and 33 degree angle. Would it be worthwhile adding to the north by north east side too? I think it looks like only a max of 3KWp per side (Maybe even only 2.5KWp) will be possible due to not being able to use all the roof as it has windows. So 6KWp (5KWp) in total would it be ok though a single 3.68KW inverter?

I'm meeting the developer on Monday and may see if I can push him to install it on all the plots (8 in total). I think if it only adds £4k most the customers will probably go for it. Also presumably the solar panel installers would offer a better price on 8 x 6KWp system rather than one. None of the electrics are done yet so it would be easy. It would also look nicer and more of the roof area could be used if both sides of a semi have PV

Martyn1981

GreatApe wrote: »

Thanks the roof is south by south west and 33 degree angle. Would it be worthwhile adding to the north by north east side too? I think it looks like only a max of 3KWp per side (Maybe even only 2.5KWp) will be possible due to not being able to use all the roof as it has windows. So 6KWp (5KWp) in total would it be ok though a single 3.68KW inverter?

I'm meeting the developer on Monday and may see if I can push him to install it on all the plots (8 in total). I think if it only adds £4k most the customers will probably go for it. Also presumably the solar panel installers would offer a better price on 8 x 6KWp system rather than one. None of the electrics are done yet so it would be easy. It would also look nicer and more of the roof area could be used if both sides of a semi have PV

That's an interesting post, raises lots of thoughts.

1. I've got panels on a WNW roof, but NNE will be a bit worse again. Check out PVGIS (see section 5 of the FAQ's for a walkthrough) and compare the ratio of NNE v's SSW.

But, and here's the important bit, it's crucial to compare that lower performance, to the lower cost of adding the 'additional' PV if you are doing the SSW anyway.

I suspect that it would be worth doing, but look at the PVGIS result and the monthly figures, as the bottom six months will probably be pretty bad, but some nice morning generation in the better six months would be good.

2. A single inverter will be fine, in fact it's a necessity to keep the cost down. The potential output of the inverter isn't the problem, so 3.68kW, 4kW, or even 5kW - the important point is that the installer will probably have to set the inverter to 3.68kW max, if it isn't already, that's not a problem.

3. I'd be tempted by a SolarEdge system, as this will make the most of the different roof orientations, and also help with any shading, but more importantly, they can cope with massive undersizing.

Solaredge specs

see that the 3.68kW and 4kW (if capped to 3.68kW) can cope with 5.7kWp to 6.2kWp of PV installed.

4. Getting all properties done, by the same installer, should help with the cost. Add in the existence of scaffolding and a free run for the cabling etc and a cost of £1k per kWp may well be possible. It might even be a bit less if closer to 6kWp per property, not sure.

5. BUT, something is nagging away at me about multi installs at the same time. I've got a feeling that the DNO will need to be asked if a number of properties are done at the same time, to make sure that the local infrastructure can cope. I may be talking BS, but that's something to bear in mind if you raise the multi property issue - at least that way you will appear informed and reasonable.

5.1 If there's an issue regarding doing all the properties, then a compromise would perhaps be smaller systems (just one roof, the best roof in each case).

This would certainly be something worth updating in case it comes up again, or just so anyone interested can see how such issues are dealt with, possible, DNO help etc etc.

Best of luck.

GreatApe

Martyn1981 wrote: »

That's an interesting post, raises lots of thoughts.

1. I've got panels on a WNW roof, but NNE will be a bit worse again. Check out PVGIS (see section 5 of the FAQ's for a walkthrough) and compare the ratio of NNE v's SSW.

But, and here's the important bit, it's crucial to compare that lower performance, to the lower cost of adding the 'additional' PV if you are doing the SSW anyway.

I suspect that it would be worth doing, but look at the PVGIS result and the monthly figures, as the bottom six months will probably be pretty bad, but some nice morning generation in the better six months would be good.

2. A single inverter will be fine, in fact it's a necessity to keep the cost down. The potential output of the inverter isn't the problem, so 3.68kW, 4kW, or even 5kW - the important point is that the installer will probably have to set the inverter to 3.68kW max, if it isn't already, that's not a problem.

3. I'd be tempted by a SolarEdge system, as this will make the most of the different roof orientations, and also help with any shading, but more importantly, they can cope with massive undersizing.

Solaredge specs

see that the 3.68kW and 4kW (if capped to 3.68kW) can cope with 5.7kWp to 6.2kWp of PV installed.

4. Getting all properties done, by the same installer, should help with the cost. Add in the existence of scaffolding and a free run for the cabling etc and a cost of £1k per kWp may well be possible. It might even be a bit less if closer to 6kWp per property, not sure.

5. BUT, something is nagging away at me about multi installs at the same time. I've got a feeling that the DNO will need to be asked if a number of properties are done at the same time, to make sure that the local infrastructure can cope. I may be talking BS, but that's something to bear in mind if you raise the multi property issue - at least that way you will appear informed and reasonable.

5.1 If there's an issue regarding doing all the properties, then a compromise would perhaps be smaller systems (just one roof, the best roof in each case).

This would certainly be something worth updating in case it comes up again, or just so anyone interested can see how such issues are dealt with, possible, DNO help etc etc.

Best of luck.

Thanks I've got an email from the developer saying sure he can do it for the plot I want to buy. But I think I can convince him to go for 3KWp on both sides of the roof so 6KWp per property x 8 properties. However I wanted to check here with you and the others if this is actually a good idea or I am in over my head making mistakes. I don't mind making a mistake for me I can live and learn but I don't want to make a mistake for the other buyers as they may have less means.

The current idea with the developer is he is going to fit air source heat pump with under floor heating on ground floor and oversized rads on uppers or LPG and a LPG boiler with traditional rads etc.

I don't want LPG and I don't have any experience of ASHPs so am thinking just electrically heat the property (very reliable cheaper than water rads & install can easily do room by room settings no water leaks etc) and offset the higher cost of buying more electric with solar PV

So first question in your view which is better would you go for ASHP or PV + electric heating assuming they cost roughly the same to install. I also assume that a small air to air heat pump in the future would not be too expensive or difficult to install if necessary? Also I am hoping space heating + water heating isn't much more than 4000-5000 units a year

Second question the PVGIS site says assuming I've put it in correctly. Assuming 3KWp

The southish side says annual production of 2,880 KWh
The northish side says annual production of 1680 KWh
That's very surprising the north side gets almost 60% of the production of the south side is this correct?

How much would 3KWp be and how much for 6KWp with scaffolding in place and easy access to wiring. Which would you go for?

I was also wondering what your advise would be for hot water.
A hot water tank plus a 1KW immersion set for peak 8 daylight hours so mostly free solar hot water. But the downside is about 300 KWh annually lost to standing heat from the tank. Or just have an electric shower and instant hot water kit no standing losses but more import less self generation and less wasted space.

Thanks for all the advise so far

Martyn1981

GreatApe wrote: »

Thanks I've got an email from the developer saying sure he can do it for the plot I want to buy. But I think I can convince him to go for 3KWp on both sides of the roof so 6KWp per property x 8 properties. However I wanted to check here with you and the others if this is actually a good idea or I am in over my head making mistakes. I don't mind making a mistake for me I can live and learn but I don't want to make a mistake for the other buyers as they may have less means.

I'll have a go, but remember these are my thoughts, not necessarily good advice!

60% for north facing sounds about right but only for shallow roofs, 30/35d or less, so it's really important to make sure it's not going to be a steep roof pitch. I've just checked on PVGIS, picking Oxford just for a test, and 30d pitch at +22d (SSW) was 955kWh's (for 1kWp), and -158d (NNE) was 585kWh's, so 61%, just as you said.

Now comes the head scratching bit, will the extra NNE PV add 60% or less to the cost. It probably will, but worth checking. Also, if you are going to have a primarily leccy house, then 'more' PV makes 'more' sense.

With scaffolding in place I'd guess that £3k or less is certainly possible for 3kWp. For 6kWp, I'd guess £4.5-£5k. But you could get quotes way, way higher, or possibly less, I'm always surprised on here how some folk can't get decent prices no matter how hard they try, whilst others get a great deal first try!

I'm not very knowledgeable on air to water heat pumps, but that's an option with a wet system, however if your info is correct about the small amount of heat needed (very efficient house), then ASHP for downstairs, with simple electric top up, upstairs if necessary may be enough. You may find that the downstairs heating warms the upstairs enough.

For a 'proper' ASHP system for the property you'll have to pay more, but I got a 3.5kW ASHP installed for just over a grand. This simply works as an alternative to GCH during the day. For example, the GCH is off now, and I'm generating over a kW, so I'll put the ASHP on now and let it warm the house to eliminate GCH needs today, and probably this evening too. So 'free' heating, give or take the £1,000's I've spent on PV.

For hot water, you will able to use diverted PV for probably 6 months of the year, with little to no import, and perhaps E7 in the other months if the tank isn't hot enough by sundown.

Whatever you decide, I'd strongly suggest you definitely get PV, at least 3kWp on the best roof. Personally, I'd go for both rooves 5-6kWp total, but that's a decision for you ....... but, adding PV later is much more expensive (scaffolding etc) and you can only apply for FiTs once, so I'd say it's now or never, and for £2k or less (hopefully) it's not worth not doing it (sorry for the double negative).

Lastly, you are right to ask for opinions from others, I'm thinking out loud and enjoying the thought process, but this is important stuff and I'm not sure I have the whole picture, and would, like you, also be very interested in other thoughts, options, opinions etc.

I hope this is helping, not making the whole issue more confusing. :think:

GreatApe

Can you point me to air to air heat pumps ideally ones that look nice inside.
I am hoping the daily heating needs in winter don't surpass 25KWh/day so even a small air to air heater would do. I assume air to air will be more reliable than air to water since its basically an air conditioning unit in reverse and hundreds of millions of those have been been installed for decades.

I assume an air to air system is an easy install so this could be done after a year or two having observed what actual heating usage etc is. Do they get the renewable heat incentive?

Martyn1981

GreatApe wrote: »

Can you point me to air to air heat pumps ideally ones that look nice inside.
I am hoping the daily heating needs in winter don't surpass 25KWh/day so even a small air to air heater would do. I assume air to air will be more reliable than air to water since its basically an air conditioning unit in reverse and hundreds of millions of those have been been installed for decades.

I assume an air to air system is an easy install so this could be done after a year or two having observed what actual heating usage etc is. Do they get the renewable heat incentive?

I don't know about RHI, I seem to recall something about it having to provide all of your heating to qualify, but also, possibly, hot water. I'm not sure.

For my ASHP (air con unit) I went with a local company called Cooleasy (not an advert, it's just that they have a nicely set out website with clear prices). They have a set install price (give or take some extra's like longer pipe runs, multiple walls and so on), and work with teams across the UK ..... I think.

Cooleasy - Bridgend

I went with a high wall mounted LG Libero 3.5kW (basic), but you will presumably want something more powerful and with multiple internal units, so something perhaps from the multi split system range.

But, but, but .... make sure you are certain of the heating needs and insulation standard, as your posts suggest minimal heating needs, but don't get caught short.

GreatApe

So I got my first quote in and others on the way. Does this sound good or bad value?
The installer pointed out that since it is a new build there is not the usual VAT which is a bonus.

Bad news is due to the roof windows positions and the standard 1.65m x 1m panel form factor it seems only 6 panels per roof side so the total KWp is going to be much less than I had hoped. If there were no windows it could be 12 panels per roof side also suggested layout seems somewhat ugly will be asking for a different more symetric layout and see what they come up with.

Anyway

The installation cost for 12 panels (3.24kWp) 6 South West, 6 North East facing would be £4,200.00 and the generation from this would be approximately 2,513kWh

We use SolarEdge Inverters and JA Solar Optimized panels both of which I have attached sheets for.

Are the panels and inverter suggested considered good quality and is the price reasonable for 0% Vat new build with scaffolding in place and easy electrics access?

Martyn1981

GreatApe wrote: »

Are the panels and inverter suggested considered good quality and is the price reasonable for 0% Vat new build with scaffolding in place and easy electrics access?

SolarEdge is excellent and the installer will most likely upgrade the warranty from 12yrs to 20yrs within the quote (around £100).

Nobody likes talking about panels, they do what they do, and feedback probably won't be available for 20yrs, so I'll keep my head down on that.

£4.2k for 3.24kWp doesn't sound cheap (given the lower VAT and scaffolding) but it also doesn't sound too bad, especially with SolarEdge. So fair ..... but you might do better?

If you have a good idea on the exact roof and window measurements, then you could have a play with layout and see if 1m by 1.3m panels might fit better. It's mostly down to luck, but that might be an option, I think they'd be about 200Wp if available. Alternatively, 1m by 2m panels, certainly worth having a play with the dimensions to see what the best fit will be.

Also, that quote must be for 270Wp panels. Given space is now limited, you'd want to consider something like 290Wp which shouldn't cost much more per Wp. Or go high efficiency, somewhere in the 300-330Wp range, but these will cost more per Wp, but it might be worth it to squeeze out every last W. And with Solaredge the panels don't have to match each other, so you could even consider putting expensive panels on the south roof, and 'normal' panels on the north roof.

For layout allow 200mm on the sides for spare, and 200-300mm top and bottom, then also allow 20mm between panels. You can probably go pretty close to the windows with the panels, as the rails will be further away (the panels will overlap).

GreatApe

Martyn1981 wrote: »

SolarEdge is excellent and the installer will most likely upgrade the warranty from 12yrs to 20yrs within the quote (around £100).

Nobody likes talking about panels, they do what they do, and feedback probably won't be available for 20yrs, so I'll keep my head down on that.

£4.2k for 3.24kWp doesn't sound cheap (given the lower VAT and scaffolding) but it also doesn't sound too bad, especially with SolarEdge. So fair ..... but you might do better?

If you have a good idea on the exact roof and window measurements, then you could have a play with layout and see if 1m by 1.3m panels might fit better. It's mostly down to luck, but that might be an option, I think they'd be about 200Wp if available. Alternatively, 1m by 2m panels, certainly worth having a play with the dimensions to see what the best fit will be.

Also, that quote must be for 270Wp panels. Given space is now limited, you'd want to consider something like 290Wp which shouldn't cost much more per Wp. Or go high efficiency, somewhere in the 300-330Wp range, but these will cost more per Wp, but it might be worth it to squeeze out every last W. And with Solaredge the panels don't have to match each other, so you could even consider putting expensive panels on the south roof, and 'normal' panels on the north roof.

For layout allow 200mm on the sides for spare, and 200-300mm top and bottom, then also allow 20mm between panels. You can probably go pretty close to the windows with the panels, as the rails will be further away (the panels will overlap).

Thanks I think they were being too conservative or perhaps read the plans incorrectly so I have forwarded on the actual plans and a suggested layout. I figure 10 panels on the south west side and 9 on the north east side should be possible so 5.13KWp using 270Watt Panels or 5.51KWp using 290 watt panels. Would 5.13 to 5.51 WKp of panels be ok on a solar edge inverter?

I have only had quotes with 270 watt or 290 watt panels. Still waiting on a couple of more quotes.

EDIT: OK quote for 19 panels with solar edge inverter: 5.13KWp for £6,565 so £1.28/watt almost the same quote per watt as the £4,200 for 3.24KWp. I was hoping £1/watt could be achieved considering no scaffolding and VAT.