Large Domestic Field Installation

[colincase]

I have decided to install a large PV system in my paddock next to my garden.
I am aiming at 9.99kWp to make the best of FIT break points. Around 50 to 55 panels, by the rough sums I have done. All in one long row of about 45m, mounted at 30/40 degrees and facing due South. Will hopefully net about £3,500 pa in FITs, savings and export, with a capital cost of around £28k. Space is NOT at a premium - relatively low efficiency panels are OK so long as they are cost-effective. This appears to be a fairly uncommon task for some of the potential installers I have spoken to.
And it raises a few questions:-
My house has only single-phase. This seems to be a problem at this power. My neighbour is definitely on a different phase - not sure about the next neighbour. How can I find out who is on which phase? And am I allowed to feed their homes with the appropriate phase? Can I charge them, say 8p per unit (between the 3.1 and 13p for export and purchase prices) And still get FITs and still export any excess on each phase? Or is there a better solution?
How do I choose a supplier for this type of system? Does anyone specialise in this size and field-mount?
Can I mount the inverter and meters in the field with the array? There doesn't seem much point bringing the DC to my house, only to have to re-distribute. And distribution losses should be downstream of the meter (preferably - obviously)

Impressed by the quality of helpful replies on this site, so I hope you can help in this case.
Thanks, Colin

 

[SolarCity]

Ground mount systems tend to be setup in two rows - one above the other as this makes the best use of space available and saves on ground works and mounting system.

You may well find that a 10kWp system is problem on single phase system but you'll never know until you ask the distribution network. It sounds like you're in a rural area which could mean you have a problem.

You cannot export electricity to your neighbours homes. How were you thinking of trying this?

You can mount the inverters and meters at the array and it is advisable.

 

[colincase]

Well - a very helpful response in only ten minutes! Thanks very much.
Good thoughts about a double row - thanks.
I was thinking that a 3-phase inverter would be needed, with each phase metered separately, with one phase coming to my house, and each other phase going to next door houses on different phases. Then we use a bigger proportion of the total output and reduce export and keep it phase-balanced (roughly). This makes more money as well as making it easier on the grid - we are indeed quite rural.
Otherwise, what to do with the "excess" power that isn't used in just my house? Storage sounds pretty difficult and expensive, and just wasting it defeats the green objective.

 

[MikeXl426]

I'm not sure ofgem nor your DNO would approve. Nor would your suppliers be able to get their heads round it. Is this green objective or a money making exercise? Probably the best way is for a 4Kw system approved by the DNO on a single phase.

 

[colincase]

I'm not sure ofgem nor your DNO would approve. Nor would your suppliers be able to get their heads round it. Is this green objective or a money making exercise? Probably the best way is for a 4Kw system approved by the DNO on a single phase.

Both (how honest is that!)

Feed in Tariff represent a steady return of something like 8% and revenue is linked to inflation. With pension annuities at around 4% when linked, and interest at 2% or so, and stocks doing what they are currently doing it is tough to find a better investment.

On the "green" side, anything that reduces the power my house takes from the grid MUST be good (whether insulation to reduce consumption, or micro-generation to supply my own) BUT micro-generation must be carbon-efficient for this to be valid. All micro-generation projects involve a carbon investment. Carbon must be used to make the devices, the steel etc and dry the concrete for installation. I have done pretty exhaustive research into the carbon balance of various micro-generation mechanisms and PV is substantially better than, say, wind power. PV gives a carbon payback of about 3.5 years and lasts more than 25. Wind turbines have a carbon payback of over 12 years - and that's before distribution and "rolling reserve" is taken into account.

So I am trying to secure a cost-effective income with a very clear conscience - and PV seems to be the answer! Am I the best PV salesman in the world? No, the answer lies in the maths. But how to actually DO it with a 10kWp system?

 

[Graeme Harrold]

You could look at it as a community PV project. You as the land owner are providing the space and capital for the project. Essentially you could fit 3x 3.6kW single phase supplying each of the houses, and you collect the FIT payment for each. You would probably be on the lower FIT payment, but you could suck that up by also investing in dual axis trackers. All of this would need planning permission.

This way you get a nice return on your money, and your neighbours get some free electricity.........

 

[colincase]

Well, with advice from some helpful chaps at UKSolarInstallers .co .uk and the post from Graeme above, it seems I have two options:-

Either persuade the nice chaps at Scottish Power (my DNO) that it can be an approved installation under G59, and get permission to export up to 10kwp on one phase (but depends on phase balance and many other things)

Or install 3 separate 3.9kwp domestic systems, one with my property address and the others at the address of two neighbours (each on a different phase). I get the FITs on all, but the savings and export only on my own. They get the free power from the other two, and their export income. Just like I had rented their roof, except they are renting my field space at 1p per annum.

Will either/both of these work? With the second option, a guide price for the investment would be about £39k (3*£13k) and the income to me with all FITs and my savings would seem to be about £4.5k giving a return of about 10% or 11%. And neighbours get some savings as well.

So thanks for the help all of you - now I need to find an installer.

 

[SolarCity]

So thanks for the help all of you - now I need to find an installer.

Your best place to look is UkSolarInstallers .co .uk - find a local firm!

 

[TedM]

Or install 3 separate 3.9kwp domestic systems, one with my property address and the others at the address of two neighbours (each on a different phase). I get the FITs on all, but the savings and export only on my own. They get the free power from the other two, and their export income. Just like I had rented their roof, except they are renting my field space at 1p per annum.

It won't work quite like that. Either your two neighbours would each have to set up a FiTs contract and assign the whole income (FiTs plus export) directly to you (so their only benefit would be the free electricity) or they keep all the money and you have a separate contract just between the three of you to allocate the funds by some % method. And remember the agreements would have to remain effective for 25 years, including for any new neighbours who might move in.

OFGEM fraud dept might take an interest too, to make sure you were on the right tariff.

 

[Graeme Harrold]

Or install 3 separate 3.9kwp domestic systems, one with my property address and the others at the address of two neighbours (each on a different phase). I get the FITs on all, but the savings and export only on my own. They get the free power from the other two, and their export income. Just like I had rented their roof, except they are renting my field space at 1p per annum.

In the grand scheme, the export and savings are peanuts compared to the FIT..... Export at £150pa on 12kW and £5-700ish on savings............

 

[Worcester]

@TedM,

I'm not sure why Colin's idea of renting them land for the ground mounts won't work, it's not too dissimilar from either the rent-a-roof schemes or what Housing Associations do. A good lawyer could draw up a contract and there is no reason why the FIt shouldn't be payable direct to Colin.

Actually if you think of it like the 'free solar' deals this is actually a better option as it's not affecting their property structure.

The downside is that although they get the free electricity, (about 20-30% of what is generated if they are lucky, or at home all the time) the properties are now effectively blighted from a FIT point of view for new / future occupants.

 

[colincase]

These are excellent points - thanks for the input.
I thought a property could have a second installation, but only after 12 months? A local farmer is installing a huge anaerobic digester in two phases for exactly that reason - his is several MEGAwatts.
And secondly, does anyone have a copy of the "standard" roof-rent contract they could email? That would be a good starting-point for a conversation with lawyers and neighbours.
Also, I have spoken to my DNO (13 - Scottish Power - thanks for the lead from UKSolarInstallers .co .ukhttp://www.************************* ) and they were VERY helpful. However. they do seem to feel that 10kWp would be too much for one phase in our rural area. But they have sent me a map of LV supplies in the road around, so I can track neighbours on different phases etc. This shows a 3-phase termination in next-door's drive, so I could even see if it's worth extending 3-phase to my house -- but I am really warming to the idea of a sort of community Installation - and that's the greenest as well - even if some of the income from my investment is "given away". Thanks again for all replies - I am an absolute beginner here, so welcome the help.

 

[TedM]

@Worcester - of course. The point I was making is that the main FiTs cannot be split separate from the export payment. They both have to be paid together to the same person.

This idea has been brought up before on another Forum where I christened it 'a meter-rental scheme' as that is effectively what the PV system owner is doing - making use of the neighbours grid connection.

Colin, you can extend an existing system. Whether this happens before or after a 12 month gap from the original installation affects how the new system is treated.

 

[colincase]

Thanks Worcester and TedM and others - all very helpful comments. I must say that they guys on this Forum seem to be some of the most helpful PV wizards around. I really feel that I have plenty of information to start a serious discussion with potential installers - and from an absolute beginners ground zero just last week.
But I need to remember Graeme Harrold's signature message! - I am definitely not an expert!
Thanks again,

 

[Graeme Harrold]

But I need to remember Graeme Harrold's signature message! - I am definitely not an expert!
Thanks again,

An expert is only someone who knows more than the person next to them!

AC kills

DC kills you proper dead.............:33:

 

[colincase]

Good point, Graeme.
And apologies - I missed a key point in your first reply on this thread. You suggested fitting a 2-axis tracker. I missed the significance of this. FIT "steps" and DNO "limits" are based on the PEAK RATING of the panel array, but the actual power generated in the year is governed by its efficiency over the year. A 2-axis tracker can increase the output of the array by somewhere between 24% and 40%. This increases the usable power output (so even greener) and also increases the FIT and Export incomes (so better payback, so long as the net cost of the tracker is not too expensive) and doesn't unduly unbalance the phase, so better for the DNO - another win-win-win solution - excellent and thanks. However, I am a bit vague on exactly how much improvement in output might be achieved. The only on-line calculator I can find is the one at the re. jrc. ec. europa.eu/pvgis/ web site. This gives results for my location as follows:-
Fixed at 36deg and -2deg East of South (both calculated by them as optimum) – output 3550kwh/y – this seems to be a consistent figure from several web-based calculators
Same but with a Vertical Axis Tracker rotating to follow the Sun from East to West – output 4410kwh/y or +24%
Now with an Inclined Axis Tracker instead following the height of the sun but not the sweep from East to West – output 4360kwh/y or +22.8%
Now with a 2-axis tracker following the Sun in both directions – output 4460kwh/y or +25.6%
The vertical and inclined axis results compares pretty well with manufacturer's claims, but the 2-axis improvement is much smaller than the 40% that is usually claimed by manufacturers. Is that because 2-axis are less advantageous in a cloudy environment like ours than in, say, Italy or Spain where they are made? Or maybe the JRE calculator is wrong? Has anyone got actual experience of these?

 

[colincase]

I've decided to abandon trackers - the reports state they work best in sunny areas (like Spain and Italy) and don't offer much advantage in areas where it is often diffused light - like Germany, for example. And I am going to start with a 4kWp system through my own meter and maybe add another 4kWp system later through my neighbour's meter. I am thinking of "ballast buckets" for ground mount - something like the "console" buckets. Any experience? Do they work OK? They apparently don't need Planning Permission because they count as "temporary structures". Is that right?

 

[SRE]

Just quick point - if you can go ahead with the field mount and supply to neighbours won't you be liable for tax on your income from the Fit that comes from your neighbour's homes and where does that leave you with vat 5% domestic personal or 20% commercial?


One of our attempted domestic 9.9kwp installs has ened up being re-submitted as a commercial installation on the advice of his accountant rather than domestic. It all makes a difference.

 

[BruceB]

The VAT is not split 5% residential and 20% commercial. It is (to generalise) 5% residential and charitable and 20% not those. So if you have a buy-to-let property and put PV on it, even though you treat the income it on a commercial basis, the VAT is still at 5%.
HM Revenue & Customs
paras 2.5, 2.9, 2.16 and 2.17 are particularly relevant.

I agree on the income tax point, if supplying the electricity on a commercial basis. The income tax exemption and reference to source legislation is below. Shared ownership might bring it within the scope of the exemption though:
BIM40520 - Domestic microgeneration: Income tax exemption for domestic microgeneration

Regards
Bruce