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Author Topic: Solar PV options on a new build house  (Read 10584 times)
ProDave
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« on: November 07, 2013, 06:49:34 PM »

I'll start by saying I have solar PV on my existing house, installed in 2011 just in time to get the original higher rate FIT. So
I know all about it's benefits.  On my existing house, the FIT income just about pays for my electricity usage, so I have "free"
electricity for the next 23 years if I stay here.

But I'm not staying here.  I have bought a building plot, just 50 metres up the road from where I live now where I am going to
self build a new, very energy eficcient house. And I mean self build, doing a lot of the work myself.

On my new house I would like solar PV, not least because I intend to heat it with a ground source heat pump (not that it should
need much heating but there's domestic hot water as well as space heating). So if the GSHP is timed to run mostly in the day it can
use all of the solar PV generated electricity (any not used going to the immersion heater).  So far so good.

Now there are a lot of trees, so there will be some shading issues if I mount the panels on the roof. So I intend to ground mount
them along the southern boundary of the plot, south of the trees, to avoid shading.  Still so far so good.

Now because this is a true self build, it could well be 2 or more years before the new house is finished, though work on the site
will start next year. Not an issue? well I think it is.

My concern is things are not stable. If I wait 2 years, the FIT may be a completley unworkably low rate, or may not exist at all
(remember the PM said he would "remove the green taxes from our electricity bills" some think that means the scrapping of the FIT
scheme after next March)

So what to do? (this may get controversial)

At the moment, as I understand it (unlike when my present system was installed) to get the FIT now, it has to be installed on a
"building" that has an EPC of D or better.

So I thought of a plan.

It will be easy to get the electricity supply onto my site fairly quickly (certainly by next March.

I have done the SAP calculations, and if I take a standard timber garden shed, erect that on the site as a "building" Insulate the
floor walls and roof with 100mm of Kingspan, then the SAP calcs says it will get an EPC of C, even with a single glazed wooden window.

So I just need an open minded surveyor willing to accept (or perform) their own SAP calculations and give me an EPC of D or better on my building

Then I can install my ground mounted panels and claim the FIT before next March.

Note I'm not asking anyone to break the law, or give false information, just to be a little open minded about the building they are giving an EPC for..

What do you think? Would that be okay?

Now, some doubt has been sown about the validity of this idea:

On a self build forum, somebody posted this:

Quote
I'm finding the whole building game is turning into a tick box exercise. The ability of anyone to use common sense and a bit of discretion is being eroded almost daily. I've just had the Green Deal assessor call me to make an appointment to visit my new build. Apparently I need this assessment in order to verify that the house as-built complies with the performance spec given to claim the FIT for the solar panels. Now, this is a new build, so has to meet building regs by law. Building regs requirements are not great, but they are above the minimum thermal performance required to satisfy the FIT criteria. Not only that, but building regs require a design SAP, plus a completion SAP report, to verify that the performance is as claimed. So, why do I have to pay for a Green Deal assessor when I will have already had to pay for a SAP report and will have a completion certificate from building control verifying performance?

So I want to hear from anyone that has recently done a FIT application to find out what they really want.  Will a simple EPC, obtained legitimately from a qualified surveyor be enough, or do you really have to go through the green deal nonsense (which would probably fail when they saw my "building"
« Last Edit: November 07, 2013, 06:58:21 PM by ProDave » Logged

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« Reply #1 on: November 07, 2013, 08:14:40 PM »

I think you will struggle with the EPC, it will have to be registered with landmark as a new address as it does not currently exist, they have to validate this and return the surveyor a new property address.

About 10% of surveys are audited which means providing pictures and floor plans of everything.

Then we have to state how many habitable and non habitable rooms, heating systems hot water systems plus the floor area on m2 - it would all stand out like a sore thumb.

I certainly would not want to risk an audit on an EPC I had done on a shed.
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ProDave
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« Reply #2 on: November 07, 2013, 08:24:41 PM »

Thanks for that.  So my plan holds no water.

What are the options for installing a system with no EPC? you get a lower FIT rate don't you?

What about "commercial" options, i.e if it were a very small scale solar farm? they don't have buildings and need an EPC?

I'm just trying to find an option before the ladder is pulled up, which may happen if I just wait until the house is built.

It would be really ironic if I couldn't get any form of FIT on my new house, which could result in me having a really suer insulated house that costs MORE to run than the one I'm in at the moment.
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camillitech
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« Reply #3 on: November 07, 2013, 09:13:23 PM »

Why don't you just do it yourself and screw the FiT  Huh

Sixteen of these http://www.navitron.org.uk/product_detail.php?proID=664&catID=135 1920

One of these http://www.navitron.org.uk/product_detail.php?proID=682&catID=123       400

A lot less hassle, it's what's going on my south facing hen shed  next to my new build Cool
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ProDave
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« Reply #4 on: November 07, 2013, 09:27:33 PM »

Why don't you just do it yourself and screw the FiT  Huh

Sixteen of these http://www.navitron.org.uk/product_detail.php?proID=664&catID=135 1920

One of these http://www.navitron.org.uk/product_detail.php?proID=682&catID=123       400

A lot less hassle, it's what's going on my south facing hen shed  next to my new build Cool

There's food for thought there indeed.

If I do go it alone, I will probably install a good deal more than 4KWp to ensure as much self generation as I can.

But what are the options now for a "no EPC" or commercial FIT install?
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ecogeorge
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« Reply #5 on: November 07, 2013, 10:20:33 PM »

Why the obsession with FIT? is it an income thing ? what is the income return ? have you calculated it? According to Camillitech you can stick 4kw on yourself for 2.5k -say 5k for 8kw WOW!!  do you need FIT -An installed FIT system will cost 5-7k won't it?
I say go big , go non FIT , go grid tie  Wink , go immersun type controller.
George.
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ProDave
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« Reply #6 on: November 07, 2013, 10:28:34 PM »

My objective is a house that's cheap to run.  Capital outlay at the build is not so much of an issue.

My main heating will be a ground source heat pump, i.e. basically electric heating. So I want to generate as much electricity as I can to help run that. And with the house being well insulated, running the heating in the day when the PV is generating should be fine and it will keep enough heat over night (if not, that's what the wood burner is for)

I'm spoiled at the  moment by being on the original high FIT rate, something I will lose when I move (oh how I wish I could take my present system and present FIT contract with me to the new house)

Yes it costs more for an MCS installed system. So for me, it's a case of working out the EXTRA cost for that, and the likely FIT income, then working out the payback time for going that route. That's if it's still available when the house is built.

I guess in the next 2 years the price of panels and inverters will continue to fall, so there's something to be said for just waiting.
« Last Edit: November 07, 2013, 10:43:17 PM by ProDave » Logged

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ecogeorge
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« Reply #7 on: November 07, 2013, 11:46:14 PM »

Don't see pv panels getting any cheaper? does anyone??
George.
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« Reply #8 on: November 07, 2013, 11:54:17 PM »

I'm with you, I reckon prices have bottomed out following the government's idiocies with the market - loads were being sold off cheap, but I think that time is coming/has come to an end of really cheap panels (which were that cheap because the market effectively collapsed, so they were being unloaded at incredibly low figures)............
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dhaslam
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« Reply #9 on: November 08, 2013, 01:02:30 AM »

There would be problem running GSHP from  PV.   If it is sunny a well insulated house  with plenty  of south facing windows won't need much heat and on a dark cold winters day   you won't have much from PV.      If  you are building from scratch  you should build a heat store under  the house  and use  thermal  solar panels to heat it.   It still would need underfloor heating pipes  and thermostats etc  but  virtually  no energy cost, mainly just circulation pumps.

The example  in the video below  is slightly different from  an optimum  system for  the British Isles  because  Mitchigan is about ten degrees farther south.  In the British Isles the store would need to be heated  for the full summer with some insulation between the store and the house floor to prevent the floor heating in summer . A small heat pump would be  needed to boost temperature  for DHW but it wouldn't  need a ground loop,  just a small mixer tank to regulate the heat pump input temperature.    Also of course  vacuum tubes instead of flat plates would improve efficiency.    The US house was built  twenty years ago so insulation standards would  have  been a little lower, I don't think the heat store would have to be quite so deep but two metres depth would be very impressive.    


 
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« Reply #10 on: November 08, 2013, 07:19:14 AM »

I think I'm with dhaslam on this one. If you're insulating to Passivhaus levels (and there's no reason you shouldn't - remember the site mantra  banghead) then heating demand should be very low - sub 15 kWh/m2/year. You don't mention house size but for a fairly typical 100m2 house that's only 1500 kWh/year for space heating. At best a GSHP would therefore save you 1000 kWh/year of electricity - 150 or so at current rates. For a 10,000 install, you're looking at 70 years just to pay for itself before allowing for cost of capital.

Personally, I'd go for an oversized solar thermal system feeding a big thermal store (one of the Akvaterm types). That'll do your heating and hot water for 90% of the year if sized right, and for the really dark months around Christmas I'd just use an immersion heater and electric resistance coil in the MVHR unit. For a peak heating power of 10W/m2 then a single 1kW fan heater could keep the entire house toasty warm - anything but the very smallest woodburner would be overkill.

How far ahead are you with the plans?
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M
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« Reply #11 on: November 08, 2013, 07:41:25 AM »

Don't see pv panels getting any cheaper? does anyone??
George.

Not sure if these count as evidence or speculation, but:

1. Ambitious Saudi Arabia Solar Plans Hinge on Capitalizing on Major PV Module Price Reductions

http://www.solardaily.com/reports/Ambitious_Saudi_Arabia_Solar_Plans_Hinge_on_Capitalizing_on_Major_PV_Module_Price_Reductions_999.html

Saudi Arabia's bold initiatives come at a time when PV module costs are dropping, making large-scale solar systems more affordable. The average selling price (ASP) for solar modules is expected to dive to $0.38 per watt in 2023, down nearly 50 percent from $0.73 in 2012.

I assume that the $0.38/Wp would be subject to 10 years of inflation, but still close to half in real terms.


2. SPI 2013: Yingli Green details long-term cell efficiency roadmap to 2020

http://www.pv-tech.org/news/spi_2013_yingli_green_details_long_term_cell_efficiency_roadmap_to_2020

Yingli Green displayed its latest cell efficiency roadmap chart, which tracked commercial-scale p-type multicrystalline cell efficiencies from 17.6% in 2013 to 19% in 2020. Yingli Green had cell conversion rates of 16.2% in 2009, 16.5% in 2010 and 17.0% in 2011.

Just to point out that a 1.4% increase in efficiency, would be equal to a 8% (1.4/17.6*100) increase in output. Whilst for example a 4kWp system, would still be a 4kWp system, higher efficiency would allow for more kWp for your money (if prices don't increase as efficiencies rise). Also a larger system could be fitted on the same size roof, even if this meant some peak generation capping.

My personal gut feeling, given the EU/China deal etc, is that we may not see prices fall much or at all, but we may instead see them hold steady, effectively reducing in line with inflationary increases. But since the panels represent an ever decreasing part of the total install cost, it's hard to say how install costs themselves will move now. I don't know if there is any more room on inverter prices or other costs, such as labour, training, scaffolding etc. Any installers able to say if this has now bottomed?

[Note, there are also a huge number of articles reporting on developments in PV technology, and alternatives to polysilicon, which may be much cheaper, but until they arrive, I'm assuming we should focus on 'normal' panels?]

Edit: Additional point, China seems to be amending/expanding it's roll out of PV in line with internal production, not sure if this is price manipulation or common sense, but they can therefore partly control over/under supply, which might prevent cheap dumping, though this is already being watched by the EU. Also remember that the EU/China deal can be revised to allow the lowering of the price minimum if international prices fall. M.

Mart.
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ProDave
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« Reply #12 on: November 08, 2013, 08:15:19 AM »

There's some interesting comments there.

I have to go to work now, but I'll reply again this evening with more thoughts on my new house and why I'm planning things the way I am.
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rt29781
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« Reply #13 on: November 08, 2013, 11:59:23 AM »

Why don't you just do it yourself and screw the FiT  Huh

Sixteen of these http://www.navitron.org.uk/product_detail.php?proID=664&catID=135 1920

One of these http://www.navitron.org.uk/product_detail.php?proID=682&catID=123       400

A lot less hassle, it's what's going on my south facing hen shed  next to my new build Cool

Does anyone know if I need planning permission to put PV on the flat roof of a double garage in Aberdeen?  Not bothered about FIT
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ProDave
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« Reply #14 on: November 08, 2013, 03:10:25 PM »

Okay, here's some details of the house and you can pass comments on my ideas.

It's a fairly modest 2 storey house, about 68 square metres on each floor. Just 3 bedrooms, a bathroom and an en-suite to the master bedroom.

The plan is to build to the best standard I can afford. It will be a timber frame or SIPS build, very highly insulated and very well sealed with MVHR. And decent high performance windows and doors.

It's not going to be coded and not certified as a passivhaus, just built to be as energy eficcient as we can make it.  I have modelled the design on FSAP2009 and it's coming out with a predicted EPC of A so that's good.  I will be disappointed if the finished house does not achieve an A. Though not certified, I probably will do an air tightness test on it, but i'm keen to waste as little money as possible getting people to certify this that and the other.

Rough calculations suggest heating requirements with an inside temperature of 20 degrees and -10 outside, will be about 2KW

We are on a south facing plot, but unfortunately there are a lot of trees along the southern boundary.  I'm going to thin them out but I suspect the council tree huggers would have a hissy fit if I took them all down.,so shading is a big issue.  But it does mean in summer, we certainly won't suffer overheating and hopefully in the winter when the leaves are down, we might get some useful solar gain, though not as much as on an ideal site.

the issue is how to heat the house and the hot water.  Strangely hot water heating becomes a larger proportion of heating requirement the more efficient the house gets.

I certainly don't want oil or gas.  I will have a wood burner but don't want that as my only heat.

So far the best option seems to be a ground source heat pump.  Because of the low heating requirement, the challenge will be to find one small enough.  space heating will be by way of under floor heating downstairs.  I'm hoping upstairs won't need any heating as the mvhr and convection should suffice,  but I'll probably hedge my bets and put an upstairs UFH loop in but at a much lower power (wider pipe spacing) just in case it's needed.

From what I have seem so far I should be able to buy a small GSHP and the geothermal piping for under 4K. Remember this is a self build. I have my own digger and it's a new site, so the disruption of laying the pipe is just my time and a few gallons of diesel for the machine.  I don't need anyone to certify it, I have already established the RHI payments are so low it would be a waste of money paying a much higher cost for an MCS company to install it just to get a tiny RHI payment. (but that's another topic)

Hot water is the thorny issue.  Heat pumps start running at a much lower COP at higher temperature.  So the plan is a direct hot water tank heated only to 50 degrees by the GSHP, that being about the upper limit before the COP gets too low.  The temperature will be raised once a week to 70 degrees by the immersion heater to prevent legionnaires.

A solar dump controller will put surplus power to the hot water as well.

I'm well aware that you get a lot less solar PV generation in the winter. I'm under no illusions, I won't be self sufficient in power.  COST of running the house is the main issue.  So at least 4KWP of solar PV seems sensible to at least reduce electricity bills.  On a cold dark winters day, I'm more likely to light the stove than run the gshp for heating, but as I have said I don't want the stove as my only heating.

The stove is a bit of a problem for us.  I would love to have one that heats water as well. That shouldn't be a problem?  But when you throw in the fact that it's going to be a double sided stove, and throw in the requirement for combustion air to be ducted in directly from outside, then I have yet to find one that will heat water (and there are only a few double siders with ducted air intake anyway)

So my big dilemma is how to keep the running costs down.  Solar PV with the FIT should do that. But without the FIT I'm not so sure. so it all depends what's available in 2 or 3 years when the house is built.  

If I do end up with solar PV without the FIT then I would want to be pretty sure I used all my power, because the thought of any "leaking" back to the grid and not being paid for would break my heart.

Lastly, I don't think solar thermal will work. Too much of a shading issue. But I'll probably hedge my bets and include a solar coil in the hot water tank, and piping into the loft to add it later should a tree fall down and solve the shading issue.  Solar PV will work because it will be ground mounted south of the trees looking out over open country. you can't remotely mount a solar thermal system like that.
« Last Edit: November 08, 2013, 03:30:08 PM by ProDave » Logged

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