bigreadie

Thinking of PV

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Hi,

 

I'm thinking of installing PV's for DHW and UFH in lieu of connecting mains gas on my new build bungalow.  We have been quoted £3k for the connection of gas to site and my current train of thought is that with gas prices increasing year on year I should just chin it off in favour of installing PV's instead.

 

The bungalow has a flat roof of approx 140sqm which faces SSW so real estate for the panels, from what I have read so far, seems to be favourable.  The only issue I can see is the inclination so would probably need some sort of frame work to mount them at a more optimal angle.  

 

I've not really looked in to any incentives for using PV generated power as from most of the threads I have read FIT is done and dusted...but what about RHI?

 

Any thoughts on my basic plan and assumptions would be appreciated...!!!

 

Thanks

 

BigR

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Sounds like a reasonable plan to me, especially if you can fit the PV without too much expense.  You can get simple flat roof PV mounts that pretty much anyone could install, as all they need is a bit of ballast: http://www.windandsun.co.uk/products/PV-Mounting-Structures/Flat-Roof-Mounts/ConSole

 

csm__MG_5497_3_760x760_79c380426d.jpg

 

The only thing to watch is the roof loading, so it would be useful to make the flat roof a bit stronger, perhaps, to take the additional load.

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At the moment there is no payment at all for new PV instalations.

 

Don't think PV on the roof will heat your house. At the time you need it most, in deepest winter, PV output is very low, it falls off a cliff in November. 

 

Assuming this is a new build, and reasonably well insulated, have you considered an air source heat pump?  Each 1KW of electricity it uses creates between 3 and 4KW of heat, bringing electric heating costs down to comparable levels to gas.  and if you then install solar PV it will help reduce your electricity costs, but it won't eliminate them.  An ASHP should be eligible for the RHI payments.

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Thanks gents for the responses.

 

We are still in the process of getting the working drawings done (hopefully this week) and then the Structural engineer can do what needs to be done with them.  I will mention the PV and mounts to him before he starts and hopefully he can incorporate the additional loading required when he does his magic.

 

It is a new build and I sort of knew the limitations with respect to winter generation and fully expect to use electric for this over that period. 

 

I have thought about ASHP but after my wife had a chat with a potential plumber she has gone of the idea.  He spun some yarn about poor performance, slow heat up times (which I had already mentioned to her) and generally poor heating output in the winter.  I am still working on her with regards to it and have a couple a quotes coming in (first one was for 8.4kW and 200litre Nibe system for £9900 which I think is steep to say the least and I have read bad things about their customer service)...others to follow. 

 

Having read through some of the forum posts on the renewables I have been bamboozled by the level detail and knowledge that some of you have and it has left me feeling like I am going in to this blind despite spending hours poring over things in the last couple of months....

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1 hour ago, ProDave said:

At the time you need it most, in deepest winter, PV output is very low, it falls off a cliff in November. 

 

… particularly if the panels are mounted at a fairly flat angle as shown in @JSHarris 's picture, or for any other plausible setup on a flat roof.

 

For gas there's not just the connection charge but also the ongoing costs (standing charge and boiler servicing) to set against the cost of electric heating which make an ASHP, as @ProDave suggests, reasonably attractive. PV on a flat roof could well help with the cost of that and the cost of DHW outside the very worst bits of the winter.

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27 minutes ago, bigreadie said:

 

I have thought about ASHP but after my wife had a chat with a potential plumber she has gone of the idea.  He spun some yarn about poor performance, slow heat up times (which I had already mentioned to her) and generally poor heating output in the winter.  I am still working on her with regards to it and have a couple a quotes coming in (first one was for 8.4kW and 200litre Nibe system for £9900 which I think is steep to say the least and I have read bad things about their customer service)...others to follow. 

 

There is a lot of nonsense talked about ASHP's by people that don't understand them, or who try to implement them in the wrong way.

 

In a well insulated house they work very well.  They work best at low temperatures so are ideally suited to under floor heating, but will work with low temperature radiators.  They will work with an unvented cylinder for hot water but are not well suited to a thermal store for instance.

 

I have been using one all winter up here in the Highlands where the temperatures are a lot colder than where you are and the heating demand is higher because of that, and it has worked without issue. Mine is only a 5KW unit which is plenty if your house is well insulated (peak heating demand when -10 outside and +20 inside a little over 2KW)

 

Where people have problems with them is when they try to replace a gas boiler with an ASHP in an old leaky house, and try to run it with the old high temperature radiators.

 

I have a 300 litre unvented hot water tank, and run the UFH directly from the ASHP, though some recommend a small buffer tank for the UFH.   You can buy a kit to to do that for under £3K.  A lot of these high quotes that some people get are from MCS installers so you can claim the RHI.  It is worth looking to see if that is really viable.  I bought my kit and installed it myself for a LOT less.  I don't get the RHI but overall is worked out cheaper.

 

You need to see the SAP assesment for your new house to see what the worst case heat input is before deciding what size heat pump you need.

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+1 to the above.  Our ASHP performs very well indeed, and the performance doesn't noticeably change in very cold weather at all.

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26 minutes ago, ProDave said:

A lot of these high quotes that some people get are from MCS installers so you can claim the RHI.  It is worth looking to see if that is really viable.

 

In my case I would rather pay a low upfront cost than have to wait 7 years to claim some of it back!!

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31 minutes ago, bigreadie said:

 

In my case I would rather pay a low upfront cost than have to wait 7 years to claim some of it back!!

 

Me too.  Our ASHP cost around £2k installed (by me, in about half a day, call it a day to allow for reading the manual, and I'd never seen one before), but the MCS installation price I was quoted was about double this, for the same size ASHP.  Quite how any company can justify charging that much money for such a small amount of work is beyond me.  I couldn't claim the RHI, as I didn't have an MCS install, but the RHI would have only given me a bit over £80 a year for 7 years, and I concluded that saving a couple of thousand on the install more than made up for gaining around £600 of RHI payments...

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I tried to use the rhi calculator and it looked like I would be in line for a decent return of 4690 spread over 7 years. Maybe the benefit has become more generous for ashp. This was for a 4 bed house concrete walls and flat roof. Some suppliers will work with your own installer so you can get rhi maybe with less costs. 

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The rate for ASHPs went up last April I think.

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The thing with RHI is that it depends on the assessed requirement, so if you build a well-insulated, low energy house then you get less RHI.  The worse the house is, the more RHI you get.

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Posted (edited)
1 hour ago, JSHarris said:

The thing with RHI is that it depends on the assessed requirement, so if you build a well-insulated, low energy house then you get less RHI.  The worse the house is, the more RHI you get.

 

Does anyone have experience or opinion of installing ashp on a poorly insulated home (but that meets the requirements re loft and cavity), and then improving the insulation afterwards?

I read up on RHI and looks like any subsequent change to the heating system is notifiable event and would involve reassessment of payments, but they don't seem to mention anything about improvements to the home.

In our case it'd be about £4000 difference (or 9000 difference for gshp) if we did it before or after the EnerPHit work.

(Less a few hundred on a totally pointless temporary upgrade in loft insulation and new EPC issued)

 

Edited by joth

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Posted (edited)

ASHP is definately the way to go 

I changed my heat source in an old  1970,sTF house

I had already  retro fitted UFH 

so all i changed was the heat source from lpg to ASHP

result-house temp --just the same

,but running costs

over £1000 a year savings going from lpg to ASHP

dumped a £1500 lpg bill +electric went up by about £500

yes mains gas is cheaper than LPG -- 

by getting my EPC done for the rhi before i did all my insulation upgrades  i got a very good grant -about £7k over the life of the grant --so it has ,or is paying for most of the work to change 

regarding MCS installation costs or indeed any contractor costs 

have you seen what an employer has to pay now!!! --its very expensive to employ staff maternity ,paternity ,pension contributions , etc etc 

even the "tea boy " needs £400 a week +NHI+pension costs -so it will be closer to £500  the employer spends 

you get £9 an hour for stacking shelfs in ALDI

so don,t be too hard on contractors  they not making that much of a killing 

lets face it thats where the  major savings are in self build --labour costs

 but yes AHSP all the way 

not GSHP too expensive -not needed in this climate

PV is a personal choice --not an economical return on investment now --IMHO

Edited by scottishjohn

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5 minutes ago, scottishjohn said:

regarding MCS installation costs or indeed any contractor costs 

have you seen what an employer has to pay now!!! --its very expensive to employ staff maternity ,paternity ,pension contributions , etc etc 

even the "tea boy " needs £400 a week +NHI+pension costs -so it will be closer to £500  the employer spends 

you get £9 an hour for stacking shelfs in ALDI

so don,t be too hard on contractors  they not making that much of a killing 

lets face it thats where the  major savings are in self build --labour costs

 

 

I don't agree, as I was quoted a price that was around the same again as the cost of the ASHP, just for an MCS install.  I did the job myself in around half a day, and I cannot for the life of me see how any company can justify around £2,000 for half a day's work, no matter what their overheads.

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Posted (edited)
7 minutes ago, JSHarris said:

 

I don't agree, as I was quoted a price that was around the same again as the cost of the ASHP, just for an MCS install.  I did the job myself in around half a day, and I cannot for the life of me see how any company can justify around £2,000 for half a day's work, no matter what their overheads.

I cannot make comment on your quote  ,or if you are really comparing like with like

post up a copy of itemised quote ,then we can see who to avoid .

nick from wales --would the man to give a balanced view on this 

could it be they sussed you out and it was "bugger off quote"

Edited by scottishjohn

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1 minute ago, scottishjohn said:

I cannot make comment on your quote  ,or if you are really comparing like with like

post up a copy of itemised quote ,then we can see who to avoid .

nick from wales --would the man to give a balanced view on this 

 

I was comparing like for like, the quote was for the supply and installation of a 5 kW Mitsubishi Ecodan ASHP, and listed the price of the Ecodan on the quote as £2.348.37. The installation cost was quoted as £2,106.11.

 

I bought a 7 kW Glowworm ASHP (in reality a Carrier) for £1,700, spent around £300 on installation related fittings so my total cost was around £2k..

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@JSHarris quote does not sound so bad.  The system I refer to that a friend had installed he paid £11K to have a Mitsubishi Econdan ASHP and pre plumbed cylinder installed.  You can buy the HP and cylinder for under £6K so £5K labour to install a nonoblock ASHP and it's pre plumbed HW cylinder.  I wonder how much RHI payment he got?

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16 hours ago, JSHarris said:

Sounds like a reasonable plan to me, especially if you can fit the PV without too much expense.  You can get simple flat roof PV mounts that pretty much anyone could install, as all they need is a bit of ballast: http://www.windandsun.co.uk/products/PV-Mounting-Structures/Flat-Roof-Mounts/ConSole

 

csm__MG_5497_3_760x760_79c380426d.jpg

 

The only thing to watch is the roof loading, so it would be useful to make the flat roof a bit stronger, perhaps, to take the additional load.

 

Ever realised these existed, thanks. What's the all up weight of one of these or does it depend on panel size?

 

Got a SW facing hip that although ideal for solar, I'd like to change to a gable ends. Don't think I'd get pp though.

 

Options to put those trays atop the dormers though:

 

Photo0093_zps9f7e4144

 

Once the roof is sorted...

 

 

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I too fitted my own ASHP that I bought (new) on Ebay fir £850, not sure what I spent on other bits but mine is very similar to @ProDave, I did pay a plumber neighbour to help with some of it but it’s been great. I think it’s a great idea though to get a rubbish SAP done to collect RHI then upgrade the insulation as it’s not notifiable 😱.

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12 minutes ago, Onoff said:

 

Ever realised these existed, thanks. What's the all up weight of one of these or does it depend on panel size?

 

Got a SW facing hip that although ideal for solar, I'd like to change to a gable ends. Don't think I'd get pp though.

 

Options to put those trays atop the dormers though:

 

 

Once the roof is sorted...

 

 

 

It doesn't seem to say in the data sheet: https://uk.krannich-solar.com/fileadmin/content/data_sheets/mounting_systems/uk/ConSole_PB_A05_EN.pdf

 

There's a photo with what looks like six off 400 x 400 paving slabs, which would be around 150kg, but it also mentions calculating the ballast weight from the wind loading, so I'd guess that this might be lower in a sheltered area.

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@Onoff,

 

Just found this info on the Renusol Console mounts: https://www.alternergy.co.uk/renusol-console.html

 

It states that they are OK for a roof that has a reserve from 15kg/m², which isn't massive.  Any roof you can safely walk on should have a reserve that's greater than this, I'd have thought.

 

Quote

Very low ballasting and suitable for roofs with a bearing load reserve from 15kg/m²

 

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Posted (edited)
2 hours ago, JSHarris said:

The thing with RHI is that it depends on the assessed requirement, so if you build a well-insulated, low energy house then you get less RHI.  The worse the house is, the more RHI you get.

 

Can you point me at the requirements to get RHi for fitting an ASHP?

 

Is there a minimum EPC like there used to be for solar?

 

So that is saying the next time I renovate a rental I should fit the ASHP first and renovate afterwards?

 

God ... what a collection of gormless f*ckwits.

 

(Feeling pungent this morning as I am working through the implication of the James Brokenshire Housing Minster’s proposal to ban Section 21 in rentals without looking past the end of his nose. One of the obvious implications combined with the fee ban, which bans everything not just up front fees as Scotland, is that if a T uses Jan and Feb rent to pay off a Christmas Credit card, the LL has zero sanctions to incentivise payment of rent except charging interest for 2 months at 3.25% which comes to about £2. I wonder what will happen. The man’s an ivory skulled virtue-signalling moron. Will start a thread elsewhere.)

 

Ferdinand

Edited by Ferdinand

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1 hour ago, joth said:

I read up on RHI and looks like any subsequent change to the heating system is notifiable event and would involve reassessment of payments, but they don't seem to mention anything about improvements to the home.

 

As far as I can tell this is acceptable within the RHI rules. Key is to get the EPC first (showing a high heating demand), then improve the insulation, then get the MCS installation sized based on your new lower heat requirements. In this case the RHI is appropriately incentivising you to improve the insulation in your home and install renewable heating.

 

If you get the same MCS company to install the insulation for you then you may get it at the lower VAT rate, but it still may well be cheaper to do it yourself or get another contractor to.

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Posted (edited)
57 minutes ago, JSHarris said:

Just found this info on the Renusol Console mounts: https://www.alternergy.co.uk/renusol-console.html

 

 

I am interested in the angle of those trays.

 

It says "Yield optimised system with an angle of 15° for minimum distance between rows".

 

My initial guess was an angle of 52º or higher would have been better given the maximum azimuth of the sun in the UK but I now see that panel-to-panel shadowing could be a major issue on a flat roof.

 

Thoughts anyone?

Edited by Dreadnaught

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