1: Solar Panels, 2: (?), 3: Profit - am I missing something?

[ChemicalChaos]

Afternoon all,

Without giving too much away, I'm in a position currently where I may soon be able to acquire freehold on a freestanding dwelling and land with enough room for at least 20kw of solar PV panels in unshaded areas of roof and land .

I'm aware that government FIT is long gone, but I've also been made aware that most energy companies are now doing their own FIT schemes, with Octopus particularly generous at 15p per kWh.

I've done some sums, and that much power at that tariff at a very conservative 8 hours a day of sunlight all year equates to £8700!!

Now, subject to a), planning permission for festooning the place with panels, and b) the local grid cables being capable of receiving that much power, am I missing some other reason why I shouldn't be all over this and why people everywhere aren't doing this?

Obviously there's the £15k up front cost of a panel-only setup (not interested in a battery bank) but even allowing for the energy use and standing charges of the building this sum would be paid back inside 3 years which makes a loan extremely feasible.

The only snag I can think of is if any tariffs are applied as energy account credit and therefore can't be extracted monetarily, would this be true?

TIA!

[Scrump]

Your estimate of over £8k return seems a bit optimistic based on my 4kw roof,panels.

[chrisch77]

I suspect your problem is that you are not going to get approval for 20kW export to the grid on a normal domestic supply. Normal allowable export limit is 3.6kW per phase on a domestic supply, so even with a 3 phase supply (is that available at that site?) you can only export half of what you propose so what does that do to your business case?

Yes, industrial users may get approval for larger arrays but they also have different infrastructure and electricity tariffs?

[JimM169]

20kwh is the max output, you're not going to get that for 8 hours a day, 365 days a year.
Not sure how solar panels a specced but suspect you're realistically not going to get 20kwh at any point even on the brightest days

[Hoofy]

"8 hours a day of sunlight"

It may be light during that time but how much electricity will you get back? Have a look in the solar panel thread.

[chrisch77]

Scrump said:

Your estimate of over £8k return seems a bit optimistic based on my 4kw roof,panels.

Also true, the output of a solar array is like a normal distribution parabola as the sun passes over. Our existing 3.6kW roof mounted and south facing array delivered approx 3MWh last year. If we exported all of that at current export rates (e.g. 15p/kWh) that only equates to £450. Pro rata for 20kW that might only be £2500 per year. If it is attached to your house then you are also going to consume some of it so it won't be exported.

[SimpleSimonSays]

We have a 6kWp array, slightly shaded, and looking back I can see we’ve generated between 4MWh and 6MWh per year over the last few years.

Call it 5MWh x 15p per kWH for export = £750, assuming we exported everything and used nothing.

Even with a 20kWp array and less shading, I don’t think you’d see the sort of production you’d need for that return, unless you’re on the equator!

[Sheets Tabuer]

ChemicalChaos said:

am I missing some other reason why I shouldn't be all over this and why people everywhere aren't doing this?

It's because you're only allowed to generate 120% of what you use or the tax man will be all over you.

[Byker28i]

JimM169 said:

20kwh is the max output, you're not going to get that for 8 hours a day, 365 days a year.
Not sure how solar panels a specced but suspect you're realistically not going to get 20kwh at any point even on the brightest days

I've 5kw of panels, install was 4 Dec, so almost the worse 3 months coming up. I've generated 362.8kwh so far, half of that is this month...
Middle of a sunny day today, I'm producing approx 3.6kw, so 2/3 of possible?

[VTC]

Byker28i said:

I've 5kw of panels, install was 4 Dec, so almost the worse 3 months coming up. I've generated 362.8kwh so far, half of that is this month...
Middle of a sunny day today, I'm producing approx 3.6kw, so 2/3 of possible?

Like Byker
my 6kw array was fitted on the 4th of Dec
total generation to date 712Kwh

I am located a fair way south of Byker still 2500 miles north of the equator.

The expected generation in the op is way over what you will see in the real world

[BoRED S2upid]

£15,000 of panels makes £8700 profit a year. I think your maths is a bit wonky otherwise every farmer in the world would be giving up on moo cows.

[No ideas for a name]

As a VERY rough approximation, I think 1kWp of panels produces around 1MWh of energy annually when optimally aligned, and at the latitudes found in the UK.

So, the OP could expect maybe a max of 20MWh annually.

I am also lead to believe that Octopus were going to lower its 15p export rate... but I can't find any evidence at present.

[Evanivitch]

No ideas for a name said:

As a VERY rough approximation, I think 1kWp of panels produces around 1MWh of energy annually when optimally aligned, and at the latitudes found in the UK.

So, the OP could expect maybe a max of 20MWh annually.

I am also lead to believe that Octopus were going to lower its 15p export rate... but I can't find any evidence at present.

I would use the same basic assumptions, so £3k/year earnings.

The issue being that you would need to be exporting 7kW on 3 phases to get a 20kW export G99, most likely.

[Rusty Old-Banger]

Harry Metcalf has recently put a video up on the Harry's Farm channel detailing his financials from solar. In winter he was getting F all. On a slightly hazy summer's day he was down 20 percent of potential, iirc.

[Cheib]

chrisch77 said:

I suspect your problem is that you are not going to get approval for 20kW export to the grid on a normal domestic supply. Normal allowable export limit is 3.6kW per phase on a domestic supply, so even with a 3 phase supply (is that available at that site?) you can only export half of what you propose so what does that do to your business case?

Yes, industrial users may get approval for larger arrays but they also have different infrastructure and electricity tariffs?

Three phase installation is a big part of the economics. We had a new 3P supply last summer….we got off relatively lightly with just under £5k bill from the DNO. That was with a 3P cable on the edge of our land. That can easily be double that and for that £5k we had to also get a ditch dug to bring the new supply to our house. That was fairly cheap but you will need electrical work done to upgrade to three phase.

There is indeed the issue of export allowance but the above is not accurate about not being able to get approval for 20kw…I have just got approval for a 50kw export limit. That said it is a total lottery and all you are assured of 3.6 KW per phase. You probably won’t know the answer to that until your G99 application is successful. Quite a long process.

We’ve only had ours for about three weeks, ours is a ground mount system. Panels are at a shallow angle because they are visible from the house.garden. When it is cloudy we’re getting about 15% of the peak, when the sun is out that goes up to about 50% which for February is pretty good. 15% of peak is enough for us to be off grid.

[Geekman]

They won't be operating at anything close to their peak efficiency for 8hrs per day. I live in a far sunnier climate and even with 12 panels on the roof they don't generate enough in winter to completely cover our usage. They do a lot better in the height of summer and will pay for themselves within a few years so I don't regret getting them, but they're definitely not a no brainer, especially in the UK.

[Evanivitch]

Rusty Old-Banger said:

Harry Metcalf has recently put a video up on the Harry's Farm channel detailing his financials from solar. In winter he was getting F all. On a slightly hazy summer's day he was down 20 percent of potential, iirc.

Harry's has a few very obvious issues he's failed to address.

[Paul Drawmer]

No ideas for a name said:

As a VERY rough approximation, I think 1kWp of panels produces around 1MWh of energy annually when optimally aligned, and at the latitudes found in the UK.

So, the OP could expect maybe a max of 20MWh annually.

Agree with this. My 4kWp panels have produced an average of 4mWh each year averaged over the last 15 (I think) years.

South facing roof 45deg inclination, no shading.

[Cheib]

Evanivitch said:

Rusty Old-Banger said:

Harry Metcalf has recently put a video up on the Harry's Farm channel detailing his financials from solar. In winter he was getting F all. On a slightly hazy summer's day he was down 20 percent of potential, iirc.

Harry's has a few very obvious issues he's failed to address.

There is something very wrong with Harry’s system. He said he was getting 100w from his 12kw system on a winter’s day….our newly installed system which is also ground mount at a similar angle (dual aspect though) to Harry’s is generating 10 to 15% of max capacity.

[LooneyTunes]

Cheib said:

Evanivitch said:

Rusty Old-Banger said:

Harry Metcalf has recently put a video up on the Harry's Farm channel detailing his financials from solar. In winter he was getting F all. On a slightly hazy summer's day he was down 20 percent of potential, iirc.

Harry's has a few very obvious issues he's failed to address.

There is something very wrong with Harry’s system. He said he was getting 100w from his 12kw system on a winter’s day….our newly installed system which is also ground mount at a similar angle (dual aspect though) to Harry’s is generating 10 to 15% of max capacity.

Agree that Harry’s has problems, but most installations have some compromises.

In our case, the price for it being invisible from the house and in a bit of a dip that limits direct light when the sun is very low in winter is that it generates <10% in winter. However, in late summer/early autumn it was producing a decent amount (not 100% sure how much it would do as we had to cap output due to cable capacity).

My estimate is that we’re losing perhaps 50% of potential winter generation (which would have been very low anyway due to short days and limited solar intensity) but will more than make that difference back by virtue of the system performing much better in summer (when the days are longer and there’s greater solar intensity).