"Solar meadow"

This story caught my eye this morning.

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college plans to spend £300,000 on a solar array generating 1076 KW and are expecting to save £150,000 a year on electricity bills. The surplus will be used locally and there is no mention of any FIT.

Can this possibly work or has someone got their sums very wrong?

Tim

Reply to
Tim
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Reply to
Andrew Mawson

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"will generate 1076KW of energy a day, enough to be energy sufficient."

For start KW (uppercase K, 1024 multiplier not 1000?) W is a measure of power (joules per second) not a measure of energy (joules).

Assuming they mean 1076kWh per day at 15p/unit that's =A359,000. If it's at the FIT rate of 43p/unit you get =A3168,878.20... But as this won't be finished until late 2012 they won't be on the 43p FIT but

21p (or something else if they fiddle with it again between now and then).

How is it going to be used locally if they are off grid or are they putting in their own loacl distribution. What happens on dull mid winter cloudy days or at night?

I think something has been lost in the translation in PR offices and journalists.

Reply to
Dave Liquorice

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> A college plans to spend £300,000 on a solar array generating 1076 KW and

Harry apparently paid about £15000 for his 4KW array. The college is paying about £1100 per 4KW (about 7.5%). 7.5% of 43.3p is 3.2p which is very close to the export tariff (3.1p) for small domestic installations so it is not totally uneconomic. If domestic installations are to get a

10% profit the college would appear to have a unit cost of about 2.9p.

If a 4KW array is expected to produce some 3300KWh then a 1076KW array should produce about 888,000KWh. Saving £150,000 on 888,000KWh is about

17p a unit so to get the saving the college should currently be paying approximately 20p per unit. (Or alternatively have I got my sums wrong).

I have no idea how comparatively large scale users are charged compared with domestic customers but 20p a unit seems high to me.

Reply to
Roger Chapman

They'd never have got onto the 43p tarrif with a development of such a scale, we still don't know the scale of it, but with the new rates they'll probably be on the 12.9 or 8.5p rates.

I'll bet the bursar had a squeaky bum one dy last month!

COuldn't see any press release on their website.

Reply to
Andy Burns

Isn't it more likely that the actual price is £3,000,000? If solar panel really could be bought for that price and pay for themselves that quickly I'm sure we'd be seeing an awful lot more solar farms.

Tim

Reply to
Tim Downie

Upper case K is a unit, not a multiplier, so they're talking about

1076 * 1024 bytes Watts. Hmm. Data processing throughput?

Oo Oo! Maybe they mean Kelvin. 1076 Kelvin Watts. Thermodynamic energy density??? :)

JGH

Reply to
jgharston

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> A college plans to spend £300,000 on a solar array generating 1076 KW and

Given that they cannot even get their units of energy right what do you think?

Reputable solar arrays are now of the order of £2/W at best so spending £300k will give them a 150kW peak PV array (ignoring control electronics and installation for the moment). In a 12h day of continuous unbroken sunshine that would deliver at most 1200kWhr per day and in midwinter they will be lucky to get 60kWhr/day on average. It would have to track the sun to do any better (which is unlikely).

Remind me how long the sunny winter days are in Edinburgh at 56N.

You could probably get the PV array price down another factor of 2 or so by buying in bulk from Chinese companies no-one has ever heard of if you don't mind taking a chance on ending up with nothing at all or dodgy units that work briefly then leak and corrode in our climate.

Regards, Martin Brown

Reply to
Martin Brown

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"generate 1076KW of energy a day"

A KW is not a unit of energy.

So is impossible to say what the thing means.

Lets say there is 1076KW of panel *capacity*. That's about 1000 square meters. Not unreasonable - say 30 x 30m.

But if they reckon to install 1000 square meters of panels for £300,000 they must be on a different planet. Id say £1000/KW capacity is nearer the mark so make that £1M installation, give or take.

Now the AVERAGE insolation in Scotland is about 90w/sq m day and night summer and winter.

So at say - 30%? - efficiency that's 30W/sq meter so 30KW average,

rounding up to 10,000 hours in a year that's 300MWh.

At 20p extortion rate per unit that's £60,000 a year for electricity whose wholesale value is about £12,000, and which could be bought retail for around £30,0000

So net savings are £30,000 against a capital cost of about £1m

ROI of 3%?

Now add in 7.5% O & M and depreciation, and the O & M bill is now £75,000 p.a.

So a net annual loss of £45,000 for a capital expenditure of a million.

You can see why solar PV is no longer worth installing when the FIT rate drops from 45p to 20p a unit.

Reply to
The Natural Philosopher

I am talking about available from makers now (at least in theory according to their websites) as opposed to "jam tomorrow" promises.

Cost to make them is bounded by the high cost of refining pure silicon or even more exotic III-V semiconductor compounds at present. If someone can produce screen or inkjet printable organic chemistry PV that is photostable in sunlight that would be game changing even if the efficiency was relatively poor. Until that happens the cost of PV will always be high because they are competing for refined silicon against the semiconductor industry and chipmakers have deeper pockets,

And you believed them? I'd hazard a guess that even for the bare screen with no electronics at all that number is low by at least factor of two.

Would you like to buy London Bridge?

Regards, Martin Brown

Reply to
Martin Brown

Their own news article is up now, but doesn't fill any of the holes

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claim to have submitted planning application in early November, but I can't see them on the list

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Reply to
Andy Burns

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It speaks volumes about their scientific and engineering credibility that the basic energy units error is replicated on their own site. It is apparently not a result of clueless idiot journalists paraphrasing and horribly mangling an originally correct press release.

I would love to see the ROI calculations that support this boondoggle!

Either they are being monumentally ripped off by their electricity supplier or someone has put a decimal point in the wrong place.

Regards, Martin Brown

Reply to
Martin Brown

The site I quoted earlier definitely states that as from FIT year 3 such schemes will only get 8.5p per unit. Mind you it also says that for domestic

Reply to
Roger Chapman

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's pre-review, try

Reply to
Andy Burns

_starting_ rate, not the rate to be paid for existing installations in subsequent years.

Chris

Reply to
Chris J Dixon

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The answer is of course to split big farms into little ones, each attracting a higher FIT tariff.. the whole thing is bonkers. More loop holes than an S & M leather jacket..

Reply to
The Natural Philosopher

I think there's something to "catch" operators of multiple smaller schemes, I've not got any reference to it though. It depends how far to the n'th degree the operators want to split their business of course, hopefully EcoBollox Group Ltd, which owns EcoBollox Site1 Ltd to EcoBollox Site99 Ltd isn't sufficient to qualify ...

Reply to
Andy Burns

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>>> That's pre-review, try

The summary on that page gives the 8.35p rate along with the information that there is no current intention to change it. There is a link to "Full information about the proposed tariffs" but none of the multiple links that lead on fits that bill.

Reply to
Roger Chapman

Yes, thae rate for larger schemes didn't get cut, but we still don't know what rate applies to the meadow ...

The 8.5p rate isn't /outrageous/ it depends if their costs really are going to be 300 grand, and if their output matches predictions. As they're a college with an 'energy dept' maybe they've got them dirt cheap in some sort of sponsorship scheme?

Reply to
Andy Burns

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> Are you sure you have understood that this table shows the

Let me pose a question of my own. What was the starting rate for domestic

Reply to
Roger Chapman

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