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

 

[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