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New 11MW solar farm sets new benchmarks in Queensland

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Dunblane solar farm

Dunblane solar farm. Pic supplied.

The 11MW Dunblane solar farm in Barcaldine, Queensland, is far from the biggest solar farm in the country, or even in the state.

But it is setting some important new benchmarks, especially in the speed of construction and the way the industry can embrace modular structures.

For one, Dunblane was entirely privately funded, and received no financial support, taxpayer subsidy or offtake contract from any government agency. It’s likely the first such project to be completed in Queensland, and one of the first in the country.

The Dunblane solar farm uses the Belectric PEG framing system, pictured above, and is so far the biggest solar farm in the world to use that system. It features close fitting arrays that allows for nearly twice the capacity per hectare as other systems.

YD Projects chief engineers Rob Mailler says construction commenced in August 2017, the DC plant was complete and inverters in place by the end of October 2017 – a period of 10 weeks and 4 days.

The plant was first energised in early December 2017 and after completing the commissioning cycle, reached full production in February, 2018.  The plant has delivered 5,000MWh to the grid so far.

Mailler says the grid connection approvals process was technically challenging due to severe local grid constraints, with Dunblane being the first plant in Australia to deliver a PSCAD study as part of the approvals process.

“The Belectric PEG system allows for a fast, high-quality build in a fraction of the time compared to other methods,” Mailler says.

It got good feedback from the Queensland Workplace Health and Safety, and also from Ross Garnaut, from SIMEC ZEN Energy who visited the plant recently and whose company has plans for 1GW of solar and storage in South Australia, and more elsewhere.

The construction of the plant was recently featured in a Queensland election campaign advertisement from the Australian Conservation Foundation. -You can see it here.

Mailler says the advantages of the system are that it needs minimal use of heavy equipment onsite, no installation operations above shoulder height, and no 240V electrical equipment on site, and light and easily manageable components.

The system doesn’t require a large or specialised workforce, so many can be sourced from local communities. For this project, a team of nine was required for the initial frame installation, increasing to 21 for the modelling phase.

solar farm

Casual team members were hired predominantly from the local community including providing work and training opportunities for young, disadvantaged people on this project.

“Local workers creating local energy, for local people – it’s a no brainer,” noted Cameron Mace, a Barcaldine local employed on the site and featured in the video (see below) and pictured above.

Projects like Dunblane that engage the local community as effectively as Meralli has will have an important role to play in the economic revival of rural and regional Australia,” says Barcaldine Mayor Rob Chandler.

Meralli Projects director Methuen Morgan says his firm is structured to deliver plants in the 200kW to 30MW range.

  

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  • john

    When a plant of 11 MW can be built with local people this just underlines the simplicity of building solar.
    Modular design simply plug and play technology the only need is electrical engineering to install and commission the electrical connections.
    Where ever there is a major transmission line how hard would it be to build 200 to 500 MW and upwards systems to connect?
    Perhaps yes needed a substations to enable this however the cost to build what would be a pretty significant supplier of energy is obviously cheap.

    • George Darroch

      Reducing construction costs is a key part of advancing the solar revolution. The knowledge gained from approaches like this one is invaluable.

  • Hettie

    Is there any indication of a selling price for the power?

    • Richard Hayes

      The article said they do not have a off-take so they are a selling spot as a merchant plant. Qld spot Mon 3pm $76.69 plus LGCs (~$85)

      • RobertO

        Hi Richard Hayes, The LGC are only available for sale in lots of 5000. Otherwise you need to use a broker to sell smaller lots. Given that each MW is one LGC this will take weeks to get to a large number, quite possible that they are selling for $50 each or even less.

        • Rob

          Actually, there is no problem selling less than 5,000 LGCs. The LGC brokers arrange LGC sales for plants at 100kW size which is 100 times smaller than this. CER only permits creation once per month, so the parcel size per creation event is 4 times what you’d expect if you’d planned on weekly LGC creation. And we have more than one plant. All told the haircut we experience for sub 5,000 LGCs when we do it, is around 50 cents.

          • Hettie

            I had hoped for a contract price to throw in the teeth of the nutters who won’t believe that solar is cheaper then coal.

          • Richard Hayes

            Do not worry about the sales price but the cost of production.

            Even with an old coal plant with the entire plant written-off

            Coal plants require 400 kg per MW-h in fuel. Thermal coal is sell for AUD 125 per tonne. Therefore the fuel is $50 per MW-h.

            Also the use of high pressure stream (all thermal plants) cost about $30 per MW-h in maintenance.

            Even with a free plant the cost is $80 per MW-h.

            Add some capital costs and the price rises to nearly $140 per MW-h.

            Solar is easy to produce at $55 per MW-h without subsidies and falling.

          • Hettie

            I’m sure that for the deniers, nothing short of links to reports of the selling price from renewable installations and both old, fully paid for coalers and brand new ones will be convincing. I doubt that tables of LCOE from a variety of generation types will be convincing.
            But I have realised that although I would like to do it, I have no responsibility to convince those deniers.
            They will learn soon enough when the coal companies they have shares in go bust.

        • Richard Hayes

          Yes, I have been trading green credits for over 10 yrs. I understand how they work and the discount for odd- lots is about 8-10%

  • Tom

    The only problem with this sort of array is that it would have a significantly lower capacity factor than single axis tracking for example. Yes I know that “baseload” is just as useless as variable power supply for meeting the demand curve (and that demand can be managed), but big high-power lumps of supply underutilise the transmission infrastructure and crowd out other variable supply.

    Some on-site storage coupled with this, even if not very efficient (such as “1414 degrees” molten silicon silos with steam regeneration) would solve this problem.

    • Jonathan Prendergast

      Looks East-West to me so would have a nice curve through the day

      • Tom

        If pretty much all of the land area is covered, then as a unit it could be considered to be lying flat on the ground.

        • nakedChimp

          The peak in the middle of the day vs. the morning/afternoon peak depends on the angle of the panels that face east/west.
          So no, from an output over time POV it won’t be the same.

          The part about having more panels point west to get a bigger afternoon peak is a different matter, but seems to be what you’re thinking of.

          • Tom

            I thought that too at first, then I realised I was wrong.

            Think about it – if 100% of the ground is covered (as it is in this picture), then the maximum solar radiation which can be caught is the same as the solar radiation which would normally fall on that area of ground. ie, exactly the same as if the panels were flat on the ground.

            Whatever advantage the west-facing panels achieve in the afternoon will me matched by the disadvantage of the east-facing panels at that same time.

            It doesn’t matter if the panels face west & east or whether they face north & south, if they cover 100% of the ground, then the net output is as if it is flat.

            The only reason that things like single axis tracking or north-faced tilt achieve better efficiency than a flat panel is that at times the shadow cast by the panel onto the flat ground covers more area than the panel itself (a long shadow). For example, a panel tilted directly toward the sun when the sun is 30 degrees below the horizon would cast a shadow onto the ground covering twice the area of the panel.

            If 100% of the ground is covered, then the shadow cast cannot be greater than the area of the panels.

          • Hettie

            Not sure if you are correct. Certainly the length of the generating day will be extended, and having the panels tilted together at the top gives a bigger surface area of panels. Two sides of a prism instead of one.
            Greatest output is achieved when the face of the panel is perpendicular to the sun, so if the single axis panels are tilted at the latitude appropriate angle to the ground to maximise year round output, and they rotate to be as close as possible to perpendicular to the sun as the earth rotates each day, their output is maximised.
            I have no idea how much a dual tilt would increase output, but someone here could tell you. The closer to absolutely perpendicular the better.
            Most of us have to accept the compromise of best pitch and as close as possible to facing solar north.
            It will be interesting to see what output this installation achieves compared to a fixed north facing array at optimum pitch.

          • Tom

            These panels are fixed, they are not tracking.

            The “advantage” of the increased surface area will be exactly compensated for by the “disadvantage” of the times that the sun is low in the western sky and the west-facing panel casts a shadow over the next west-facing panel. (assuming they are east-west tilted)

            Think of the total shadow cast. This is the total radiation collected.

            Don’t complicate it – the simple answer is the right one.

          • Hettie

            My musing about tracking was a digression. The array as installed will have an output significantly higher than if the same ground area were covered in flat panels.
            Longer generating day, better angle to the sun, greater surface area. The shadows cast are a function of pitch , but are a red herring.

          • solarguy

            Compared to a fixed N array about 5% loss, but better than completely flat.

          • solarguy

            It does matter if it’s north south, better east west than flat by a long shot.

          • Tom

            Only if there’s gaps between the “valleys” to accommodate shadowing. In the pictures there are not. Therefore east-west is exactly the same as flat.

          • solarguy

            Look Tom, the shadowing is of no consequence at such a shallow angle (looks like about 10 degrees) shadowing from a low east or west sun doesn’t matter as the solar day is over at those sun angles. In the early morning the situation is reversed.

          • Tom

            You’ve just proven my point. The increased surface area at 10 degrees is a minuscule advantage, exactly offset by the shadowing which is a minuscule disadvantage. The morning efficiency of the (presumably) east-facing panels is exactly offset by the morning inefficiency of the west-facing panels. The net effect is that an array of ANY design which covers 100% of the area that it is built on will have exactly the same solar radiation collection as panels that cover the same area and lie flat on the ground.

            The only reason for the slopes is to allow rain to run off and to rinse the dust and bird poo off.

          • solarguy

            The shadowing will be at very low sun angles, 10 degrees pitch will come into it’s own a bit later after dawn when there is no shadowing on the west pitched panels. And if you think about it the east panels will reflect light onto the west panels, except the very edge of the array. This increases output over flat array considerably. Having said that it would be interesting to model the difference between this idea v’s tracking array on the same land area, considering cost issues of the latter.

            10 degrees is the min self cleaning angle, but in periods of no rain cleaning is going to be a bitch, unless they develop a robotic duster of some sort.

            Anyway, I don’t think you will believe any of this and that’s your problem, but here’s a take away thought, do you really think these people would have put their money into this design without modelling it first!

          • Tom

            I’ve modelled it all (except the shadowing – that’s really hard to do). The magic formula (which took me 2 weeks and lots of sheets of graph paper, mostly scribbled through, to work out) is as follows:

            cos theta = (cos alpha sin gamma) + (sin alpha cos beta cos gamma)

            Theta = the angle between the direction the panels are facing and the sun’s rays. Cos theta is what you really want to know – this is the efficiency.

            Alpha = the angle of tilt of the panels above horizontal

            Beta = the horizontal deviation of the sun from the direction of the panels (eg, if the panels were facing North, and it was 9am, and meridian that day is 12 noon, then beta = 45 degrees)

            Gamma = the height of the sun above the horizon.

            Plug these into excel, perform these calculations as many times as you want to for different scenarios (hourly, half-hourly, whatever you want), draw the graphs and see what you come up with.

            I know what you’ll come up with because I’ve already done it.

          • Graeme Harrison

            Tom, re your claim “I’ve modelled it all… The magic formula is as follows: cos theta…” is a simplification.

            ‘Cos Theta’ problems are:
            1. It does not take into account surface reflectivity as a function of theta;
            2. It assumes uniform/linear performance of PV cells over light levels from zero to max solar radiation. It is known that at low light levels (eg panels in shade) become a ‘load’ on those generating (if in series);
            3. It assumes maximising for total MWh produced, not matching generation to any demand curve (ie the different worth of a MWh at different times of the day).

          • Tom

            Graeme Harrison – on Point 1 and Point 2 I agree. However, Point 2 would mean that the array demonstrated in the pictures would work even less well than a flat horizontal plane of panels, as the panels facing away would become a load more readily despite the other panels facing toward the sun.

            On Point 3 – my formula is for a point in time – you need to repeat the formula dozens of times (or use integral calculus) to produce the area under curve (total MWh per day). So I disagree. The daily generation curve with the pictured array will equal the daily generation curve of a horizontal array (notwithstanding your correct points 1 and 2).

            At a given point in time, the increased power of the panel facing the sun will be exactly offset by the decreased power of the panel facing away from the sun, hence the daily generation curve will be equal.

            If you want to think of it really simply – the use of the sun is a choice between electricity generation and grass growing. The greater the shadow cast, the less grass grows, and the more electricity is generated.

            In a single-axis tracking array, the row of panels may be 2 metres wide, and there may be a row every 8 metres. Does that mean that 75% of the grass that can otherwise grow will grow between the rows of panels? No it doesn’t, because on average the shadow of the panels shadows a greater ground area than the area of the panels themselves. The grass would be restricted to about 60% of its unshaded growth, as the panels capture about 40% of the available sun over the whole area.

            Similar with fixed north-facing panels – they may cast a skinny shadow at 6:30am shadowing less area than if these panels were laid flat on the ground, but at noon (especially in winter) they cast a longer shadow than their area, such that their average shadow area is greater than the area of the panels.

            The above array’s shadow area is equal to the area of the panels.

          • solarguy

            The only time that an horizontal array would work better than the one in question is briefly at noon, but at 10 degrees not by much.

            Of course tracking arrays will produce more output for any given array size, but at a much higher cost and require greater land area.

            I think your missing the big picture here Tom.

          • Tom

            The big picture is pretty much what I said in my original comment in this thread.

            This sort of configuration is good for many reasons. It is cheap and fast to install, and it packs a lot of power into every hectare.

            However, as I said in my original comment, the ONLY problem is that this configuration produces at a low capacity factor, and short periods of lumpy power crowd other variable energy out of the transmission capacity. I also said that some on-site storage would solve this, if it could be installed & operated cheaply enough.

            The thread then became an argument about mathematics, as many people were fooled the same way that I was fooled when I first read about this sort of array on this site about a year ago. It seems that everyone finally agrees that I was correct about the basic maths, as the arguments now are about reflection and non-linear performance rather than capacity factor and power curves.

          • solarguy

            It won’t be as low a capacity factor as you would think Tom. I have 9.3Kwp in two separate arrays, 3Kw is facing due west at 15 degrees tilt. In summer either side and including the solstice that west facing array produces very bloody close to half of the north facing 6.3Kw array’s daily output which has a 22.5 degree tilt, both have their own MPPT chargers……….ummm that’s interesting isn’t it.

            Think of what the daily production would be if I had another 3Kw facing east on the shed……. that’s right it would be virtually the same as a north facing 6Kw array, now it doesn’t take much imagination to realize that you would get a similar result if not better at 10 degrees, with panels facing towards each other east and west.

            As far as lumpy power goes, there wouldn’t be any.

          • Tom

            You conveniently forgot your south-facing panels.

            If you’re going to talk about 100% surface area coverage and you’re talking about north-facing panels, you have to talk about your south-facing panels too.

          • Hettie

            What good do you expect south facing panels to do? ANY where but in the northern hemisphere or very close to the equator, in the southern, their output would be miniscule.

          • Tom

            Not much good, but Solarguy was comparing apples with grapes when he was comparing his array of some north-facing, some west-facing, and potentially some east-facing with the array that we are talking about. If you have 100% of the ground area covered and you have some north-facing panels, then by definition you also must have some south-facing panels (unless you are on a steep north-facing hillside, which this is not.)

          • solarguy

            Yep, south will only make sense if every part of your roof is filled with PV, but south will only give you joy in early morning and late arvo in summer for the most part, winter output a frigin joke, a complete waste of money. But you can reverse pitch to north on a south facing roof, but usually only a single row depending on the pitch angle and depth from ridge to gutter.

          • solarguy

            If your in the northern hemisphere south is king, but why talk about south facing panels in Australia, unless the array is very north latitude?

          • Hettie

            I may be dead wrong , Solar, but my thought is that for best all year round performance of fixed panels, the pitch should maximise winter output, to compensate for summer’s longer days.
            Best output is achieved when panels are perpendicular to the sunlight, yes? The lower winter sun means panels should be more steeply pitched. Actual optimum pitch is of course latitude dependant, so the higher the latitude, the steeper the pitch of the panels.
            So I am surprised how flat your north facing panels are. And the east and west pitch would need to be higher again because the sun is lower.
            At 31° south, I was advised that 24° elevation is optimal, so built the house with that pitch of roof. But I think you are in SA, so would have expected you would have pitched higher, given your relevant expertise.
            Where am I going wrong?

          • Hettie

            Yaayy!
            30.5 kWh .

          • solarguy

            Where are you going wrong. Well my dear, firstly I live in Maitland NSW, 3hrs drive from you and you have forgotten that. The house roof is 22.5 degrees std pitch and was not my design, but that’s ok for winter, just as 24 is ok for yours, bugger all in it really. Obviously north pitch ain’t flat.
            Shed roof is pitched E to W and has 15 degree angle, built to a budget and summer PV performance, besides west is chocka block holding 16 x 190w panels. Good enough to make 11kwh on a sunny July day, summer it will make up to 20kwh on a cloudless day. Couple that with the 6.3kw north array=shit loads of power.

            Just FYI, optimum pitch in winter is latitude plus 15 degrees, best to have dual axis tracker, if you can afford it!

          • Hettie

            Oh dear! I’m clearly losing my marbles. Yes, I had forgotten that it was you in Maitland. I knew somebody was…and then I got all muddled about the angles of your panels, mixed up by Tom’s wittering.
            In my defense, I’ve had a bit of trouble with back and hips of late, and am spaced out on painkillers.
            It’s a bugger getting old!
            That’s a nice simple formula for panel pitch. Should be taught in school geometry. It seems mine are 2° flatter than best. But 30.5 kWh yesterday is pretty happy making.
            Yours must be a fairly power hungry household. But then there’s only one of me most of the time, and my 20 x 265 panels give all I need and more.
            Yet to see what the RCAC will use. It went in on Friday, and makes no more noise than the sound of my own breathing. Yesss.

          • solarguy

            Look all cool, I get a bit zonked on pain killers myself and thank the sky fairy for codeine, nurophen, diclovfenac and prednislone.
            Unfortunately the methotrexate honey moon is almost over for me, need to add another liver toxic drug to the mix, says specialist. Oh joy! Immune system still too aggressive, damn thing just won’t lie down. “Talk about the enemy within”

            Our power requirements vary, as little as 9kwh, mainly 15kwh, but up to 35kwh on those roasting days and nights and that all includes battery charging and losses.

            Great to hear you now have RCAC, you’ve been waiting for that for a good while now, bet your pleased as punch. Don’t forget to pre warm or cool before sundown to make the most of your PV production when needed. If you need any operating tips to get the most out of it, I’ll be only to pleased to help.

            P.S. I wonder what Tom’s on for all his dribble, it’s obviously bloody good!

          • Hettie

            Your health issues sound far worse than mine. Commiserate onshore. Methotrexate is heavy duty. Mostly I get by on regular panadol osteo, but have tramadol for the bad patches.
            The RCAC is set on timers. 07:30 to 09:30; 17:30 to 10:30. 21.5°C.
            As long as there is a bit of sun, the house is warm all day. Just starts to feel coolish around 17:30.
            In summer, I’ll reset the timer to 23°C, 14:00 to16:00. By 17:00 it starts to get cooler, and time to open up again
            Coupled with full heat exclusion measures, and max cool overnight air, that should be plenty.
            Losing the $100 gas bills each winter month should more than compensate for a bit more power.
            I’ve been buying around 3, 3.5 kWh a day since the panels went up. Was 8 to 10. Doesn’t sound like much, but it adds up to around $45 a month.
            And of course I’m stoked that the panel output is so much greater than the 20 kWh a day I had budgeted on.
            Just wish I could convince more pensioners that going solar now, even if they have to borrow, will save money from day 1.

          • solarguy

            Oh yes losing the $100 gas bill will a great win. As the colder days are yet to come can I suggest what we do here. As any A/C uses the most power in the first hour of running, even inverter types, turn it on at 15.00 set @24c or even higher, as the room warms up, turn it back down, It will be run by solar if there is plenty of sun. After the first hour it will just lope along using very little power into the night( as low as 200-300whrs) when you have to use the grid. You may find you want to turn it off before 10.30.

            On those 40c + days that keep the temp up well into the night like into the 30’s and opening a window would be madness, it won’t use much power at all. Same thing as winter regime, get it colder first then adjust up. At what time you turn it on in summer is up to you and the ambient temp. Just let solar do the job early enough, after all it’s free.

          • Hettie

            All good advice, but a few things are worth pointing out. In Armidale, our hottest day so far has been 37.5°, and careful management has kept the inside temp to 25° on days like that. I do prefer to be a little cooler. Because it is so high, elevation 1000m above sea level, temperature drops she reply from 4.30, 5.00, and ovenight minimum has not been above 20°. More like 15 or 12. Single figures more often than not.
            So as soon as it is cooler outside than in, I open everything to exhaust the warmer air, stay open overnight with fans going to drive the cool air down onto the exposed concrete floor. Shut up shop when I get up.
            So to get the little bit of cooling that I want, the plan is to set temp to 21° and run from say 2.30 to 3.30, 4.00.
            Heat gain after that will be minimal.
            Now and through the winter, timer is set for 21° by 7.30, off at 9.30 when the morning sun is warming up nicely. On again for 5.30, because it stays warm until then. Off 10.30, but I often go to sleep in my chair and will wake up, a little cool, around midnight and toddle off to bed.
            With the gas, I had the same timer regime, and the house maintained 16° to 25° year round. Of course in rainy days in June, I would override the timer. Home most of most days. Winter here is clear skies and sunny. Low rainfall. Summer is wet. But June has been miserable last few years.
            It will be interesting to see how it pans out.

          • solarguy

            On the hot water, couldn’t have been better timing. If you have instant gas hot water and don’t shower long, you should notice a big difference.
            Falling asleep in the chair happens to me too, but there is one thing I would like you take away about A/C use and that is if there is sun use it to get things up to speed with free energy well before 5.30 pm. Take note of how much your inverter is making between 3pm through to sundown, which is about 5.10pm for me at this time of year. Trust me it works a treat. By all means experiment, just remember the PV bell curve and work within it for the most benefit of your finances. Penny saved is a penny earned.

            You may be interested that I bought a portable induction cook top to make use of free power and save LPG gas. Not that gas cost me anymore than $18/q, it’s because I’m an energy tight arse like my old man was. Survival trains hard.

            Good luck.

          • Hettie

            The air con wouldn’t kick in much before 5pm, because the house is too warm. 23, 24°. The big heater in the sky does that without any intervention from machines. Orientation, double glazing, double thick concrete floor where the sun hits, and that’s from sunrise to sunset once the leaves are down. Walk around in socks on the concrete in midwinter for truly toasty toes.
            It’s hard to compute until you live it. So I’ll take the saving on gas as the prize.
            Ah, it just woke up to take the room temperature and immediately went back to sleep.
            Temp outside is 16.3. Inside it’s 23. (4.21 pm)
            High light cloud, 489W.
            Wish I had some west facing panels!
            I’m thinking the gas will be about $10 a month. More when I have a guest. AirBnB. Not much of that now until the August UNE intensive schools.

          • solarguy

            My west facing PV only producing 230w now 4.42pm and it’s a 3kw array. This time of year things drop off fast and that’s what I’m on about. If you can tolerate setting @ 25-26c from 3-4pm you can turn it down after that and it will lope along well into the night, because you got over the 1st hour max consumption hurdle all powered free from your PV, then the grid power you use after that will, be chicken feed.

            I’ve been in a house as efficient as yours and they are great, so I understand fully.

          • Hettie

            Uhuh. I’d burst into flame. Sometimes you make choices. I hate being hot even more than I hate being cold.
            FIT 12.8, price to buy 26.21, ac has scaled right back after only 10 minutes. Nothing in it. And so quiet.

          • solarguy

            So you’re not as frugal as I thought then. Do you know the input power of the A/C?

          • Hettie

            The Powershop half hourly readout for Sunday and yesterday (bar graph only, so not very accurate) suggest a total of about 800 W for the first hour in the morning, with outside temps around 6°, then about 150 W until the sun kicks in. In the evenings, the first half hour looks like around 100, settling back to around 50 until it shuts off.
            As I said, in the evenings the room is already at the preferred temp when the ac kicks in, so apart from warming the unit itself, there is little if any initial extra load, just temp maintenance.
            Daily total 4.9, 5.2, up from around 3.3.
            So cost around 50 per day.
            I can live with that, if it is going to be saving $3.00 a day or more on gas.
            When 7.00 am temps go down to minus 3 it will be different of course. Although inside will be not much cooler than now, there will be a lot less heat outside to work with. Rated to minus 15°, sheltered position, never frost on the ground, and the end of the outside unit gets the earliest morning sun.
            What do you think?

          • Hettie

            The unit itself is rated 6kW heating.

          • solarguy

            That’s all interesting, but I meant, what was the compressor input power required for heating and cooling. Info will be on a sticker on the outside unit and or in the booklet that came with the unit in the specs page?

            What do I think about what exactly?

          • solarguy

            Ok, I can’t discuss the maths modelling as I’m not qualified and perhaps you haven’t formulated this correctly (see Graeme’s comment below)

            An engineer from Fronius, tested the real world output of an east/west array tilted 30 degrees with a single tracking MPPT inverter on a building. Now shade really came into equation here, but the array’s output was only 5% less compared to a north tilted array.

            Some years ago I designed an e/w array at 22.5 degrees for a customer, but with a duel tracking inverter and the results have been fantastic.

            Now the array that we have been discussing is tilted even lower @ 10 and not on a building, so shade will be very transient and only at very low sun angle, when even 90 degree angle wouldn’t amount to much output, dawn or dusk. And perhaps they are using duel tracking inverters too.

          • Hettie

            Tom, Tom, it’s not the efficiency that is at issue, but how early and late in the day the panels can generate.
            My solar array all faces 4° west of true solar north. Insignificant.
            Well, no. Output from sunrise to solar noon (about 8 minutes later than AEST noon) is consistently about 2 kWh less than the output from noon to sunset.
            As I am a late-ish riser, that is no disadvantage to me. Plenty of solar power happening by the time I am up, and enough to power the aircon a bit later than those whose panels are on exactly solar north.
            Besides, unless there are micro inverters, one panel with lots of bird poo will cripple the whole array. Clean panels are more efficient.

          • Tom

            I just gave away my magic formula to Solarguy immediately below this comment.

            I challenge you to pick some arrays, plug the numbers into Excel, and draw some graphs.

            Keep the sun high enough to avoid shadowing, or otherwise you can work that bit out for yourself. Shadowing is too hard for this formula.

            You will find that if 100% of the ground is covered, then whatever the array the efficiency will be exactly the same at any time of day as it would be if it was one great big flat panel laid on the ground.

          • Graeme Harrison

            Tom, you are wrong in your claim “if 100% of the ground is covered, then whatever the
            array the efficiency will be exactly the same at any time of day as it
            would be if it was one great big flat panel laid on the ground.”

            The more acute the angle of light hitting the surface, the greater percentage is reflected back to space, with less entering. That is why glare off water etc is worse in winter (lower sun) than summer, even though the sun is ‘stronger’ in summer (higher lux).

            If you are trying to supply a local load, better to have some with East & some with West orientation to ‘smooth’ generation over hours of significant sunlight. Personally, I would also have more West-facing (and steeper West-facing) as the ‘peak’ shifts more to evening, though I understand this opens up ‘gaps’ in the panel rows.

            Also, some North-slope is worthwhile away from the tropics, but this site is at edge of tropics. It reflects how cheap the panels now are, that this site’s arrangement is to best utilise long thin strips of metal for affixing, rather than worrying about peak orientation. The bigger challenge is how such installation will go with ‘whirlies’ (highly-focused low pressure areas at bottom of twisting column of air – that can rip roofs off farm sheds). Whirlies exert very different forces on gapless surfaces above ground-level, compared to consistent strength winds from a given direction. They pull a surface ‘up’ with great force.

          • Mike Westerman

            I further problem is drainage during tropical storms – they may not be frequent but when they happen the precipitation depth/hour can be very high.

            It’s great to see innovation in deployment, as now that panels are so cheap, labour for deployment and support structures become a significant factor.

          • solarguy

            You certainly have a point with the whirlies. Looking at the video there are gaps between the strings that could minimize damage from events like that. And if the strings are anchored well, it may just be able to handle it

          • Hettie

            No. Not going to play. Not my game at all.

          • solarguy

            Tom mate you are so wrong and you can’t be told!

          • Tom

            Ok, I’ve wasted a few hours of my life plugging in the numbers and producing some graphs.

            I’ve assumed 30 degrees south, summer equinox, meridian at noon. Each graph has 33 data points, half-hourly from 0400 to 2000 inclusive, and the data value ranges from 0 to 1.0, being the proportion of direct radiation being received at that point in time.

            I have compared a completely flat plane of panels to panels tilted 20 degrees east and 20 degrees west.

            First, this is the capacity curve for the horizontal array:
            https://uploads.disquscdn.com/images/0daaa86bc7e855d5b4ae9fe3921012be6fe6b9887137bb9cc63bfb03ed09bfd5.png

            Next, the capacity curve for the 20 degree East-facing array:
            https://uploads.disquscdn.com/images/9909bb72a9eda85a160411f06a7393b52c2e82cec0d8e4201960223f76f5c187.png

            Next, the capacity curve for the 20 degree West-facing array:
            https://uploads.disquscdn.com/images/941cf97c89382bd973862ea8e85fac6fb1efe599329a3f6877342ae5b6414d71.png

            Now, combining the east- and west-facing arrays:
            https://uploads.disquscdn.com/images/77a20921b16026cf90b113d034c6b02b707047bba07f479ec9dae23d13cca52f.png

            Very similar to the horizontal array. How similar? Let’s subtract the combination east-west curve from the horizontal curve:
            https://uploads.disquscdn.com/images/acf655ea2a615a48f36b463a339b273500b271ba754e67459f123b07334d5634.png

            Why the differences between the two curves?

            For most of the day the flat panels have a slightly higher EFFICIENCY than the east & west panels behind. But the flat panels cover 6.4% less area, as the east & west panels are the hypotenuse, and so need to have a greater area of panels to cover the same area of ground. This is the exact difference in efficiency, ie, covering the same area of ground the same power will be generated at any point in the day.

            In the first and last 1.5 hours of sunlight it appears that the east-west array has a significant advantage, and it would, if there was enough space between the panels to avoid shadowing. But this are the exact times when the sun is below 20 degrees high, and so (in the evening for example) the west-facing panels would cast a shadow completely shadowing the adjacent east-facing panels, and then partly shadowing the next row of west-facing panels. My maths isn’t clever enough to calculate the exact shadowing.

            It’s obvious really – there is only so much solar radiation landing on a hectare of ground, and if that entire hectare is covered by solar panels then it doesn’t matter how those panels are laid out, they will capture the same total amount of radiation whatever the layout. There is still no such thing as a perpetual motion machine.

          • solarguy

            Before going any further in this discussion, answer this question please.

            When comparing output of horizontal array and E/W tilted array of 11MWh each. What would be the output difference be, between the two on a completely overcast day?

          • Tom

            If 100% of the ground was covered, the difference between radiation collected would be zero. The radiation collected would be equal to the radiation which would usually fall upon the now shadowed ground.

            The only differences would be to do with non-linear efficiency, glare etc, and if overcast these are likely to be miniscule.

          • solarguy

            Well at least you got that right. Now for what you have gotten wrong.
            Barcaldine is 23.55 degrees south, not 30.
            Tilt angle 10 not 20.
            So don’t assume anything, know the facts or shut up.
            Now it beats the shit out of me why you haven’t taken any notice of your own modelling. In the graph for horizontal output compared to east and west, which shows for both the output starts earlier and later in the day. Not only that there is more power for those times in comparison to a horizontal array. It completely ignores reflection off those E/W panels facing to each other at certain times of the day, and that will increase output.

            In ending, if I was designing a solar farm like Barcaldine and I am a CEC accredited PV system designer even though I don’t do jobs that big, I would design it with separate MMPT for east and west panels and parallel the output, making the most of the design. And the guys who designed it, may just have done it that way for all I know.

            If you superimpose east and west graphs you might twigg as to what I’m on about.

            It took me 5yrs to get my qualifications, what qualifications in PV do you have?

          • Hettie

            Oh solar, you can’t argue with stupid

          • solarguy

            That’s right Hettie, you can’t educate f%&k wits!

          • Hettie

            But by losing your temper you lose anyway.
            However, the provocation was pretty horrible.
            Please just block him.
            You probably know this,The little down triangle at top right of a comment gives you that option.

          • solarguy

            Here what you’re saying, but I didn’t really lose my temper. If you see a blinding flash, feel heavy seismic action and a mushroom cloud, then you know I have really lost it. LOL.

            Luckily I haven’t got a short fuse, well most of the time I haven’t. I suppose who ever relights the damn thing again, gets the good news quickly.

          • Tom

            You’re just grumpy that you’ve been proven wrong.

            I only bothered in case you were in the industry so you don’t give bullshit advice to paying customers.

          • solarguy

            It’s you that has been proven wrong idiot, you google goof ball. A little bit of knowledge in the hands of an uneducated fool is a dangerous thing. And it is you that is grumpy because you have been caught out with a hand on each dick. Knew all along you were a goose. You have been told by more people than I that you were wrong.

            For all your BS math modelling all you came up with was a big load of jizz. And as for advice, if you don’t know what your talking about, just shut up!

          • solarguy

            Micro inverters are so old now, latest tech are dc optimizers and cheaper too.

          • Hettie

            Ah, what it is to be in the industry and up with the latest tech.
            It’s moving so fast now. My info is nearly a year old.
            It’s the progress towards 100% renewables that keeps me interested here now. But the news about FITs going down is a downer. State election due March 23 2019. Hmm.

          • solarguy

            Yep, let’s hope we can kick Aunty Gladys and her morons out on there arses!

          • Hettie

            I have a nasty feeling that the sports stadiums might be a winner for the great unwashed, and there are a great many of them. Not so many thinkers.
            There are also a great many homeless, who have no reason to love her. Let’s see. The Sydney train commuters.
            The people displaced by Westconnex. Everyone who hast to drive in central Sydney, and everyone who has a business affected by the traffic mayhem from the light rail debacle – perhaps the list is long enough to see her tossed.
            Especially as she was transport minister before she was premier, and all the stuff ups are down to her. Ordering trains that are too big for the tunnels, or not making the tunnels big enough was a spectacular exhibition of competence.
            Not.
            Can you see them surviving?

          • solarguy

            Both my mother and grandmother were grassroots Labor girls and every thing they said about the Libs when I was a kid and into later life was just so true. And about the low income unskilled workers who voted Liberal and were scared of commies, believed the Libs were better economic managers and used twisted logic in their arguments, all the while getting screwed by low wages and bad conditions. But how could they believe that, how could they compare, when Labor hadn’t been in power since just after the war.

            Well nothing much has changed, although now mum and dad both have to work in order pay off a mortgage and the bills. Hell I could go on, but I haven’t got time, I’m sure you now what I’m on about.

            The Libs have stuffed up Newcastle with light rail too, the idiot business council were all for Glady’s stupidity, but now some of their members are suffering big time.

            They have done more than enough to piss people off and I think we just might toss them out. I’ve been in the ear of our local Labor MP about changes to the state building code and RE,. Fingers crossed they may make this policy.

          • Hettie

            A decent subsidy for retrofitting energy efficiency features like double glazing and external shading, as well as insulation would be good. Drive employment, reduce energy use and cost, all that good stuff.
            All those weather board houses with timber floors should get underfloor insulation with good thick foil board. Plenty of skinny youths who would slither around in the crawl space to do it after fumigation for spiders and rats.
            Landlords could get extra to encourage them to bring decrepit old rentals up to habitable standard.
            Anyway, the battlers have finally realised the Libs are out to rob them blind, and the daft Australian thing of not sacking a first term government does not apply, either at state or federal level.
            Let’s keep everything crossed.
            If Labor does all that it has promised to give the 1% a real haircut, there will be pots of money to bring about real change.
            Dog knows we need it.

      • solarguy

        Go to the top of the class.

        • Tom

          Not the maths class though.

    • Rob

      Lots of thoughtful comments there on the effect of panel orientation on production. The comments are quite right, we did do comparative analysis very early in the design phase to properly understand the trade offs between various mounting options. Indeed to raise capital for a project like this its pretty much mandatory to do a PVSyst analysis which covers the effect of panel orientation and a range of other issues like DC:AC ratio options and site specific annual irradiance and temperature among other things. We then sought proposals from various contractors for each of the mounting options and took into account the different O&M costs for each option. The commenters are correct, per DC kWp of PV array, the Belectric PEG system produces less than a tracker and also less than a fixed tilt north facing system, but crucially it also costs a lot less to build and maintain. You could cite a relative production figure for each option but that isn’t meaningful unless you also cite the DC:AC ratio being considered, and the reality is the right DC:AC ratio is both site specific and different for each mounting option, so comparing all options on the same DC:AC is a classic tactic to win an argument under false pretences, each should compared at its own optimal DC:AC ratio and that will need to be individually determined at each site. The answer changes again if you are say planning to add a future DC coupled battery.
      We can’t get to the right solution for a site by looking at a single issue in isolation, even an apparently unrelated issue like grid connection cost can change the final choice in a proper financial optimisation. The financiers view on the forward energy curve can also change the choice. As an example, in the face of uncertain forward prices, a rapid payback is a useful thing so you will tend to favour a lower cost solution. There are a lot of subtle factors to consider and include in the analysis. In the end it wasn’t even close for the Dunblane site. The Belectric PEG system delivered the least cost per kWh delivered.

      • Tom

        Awesome comments Rob – thanks.

        I need to learn more about factors affecting DC:AC ratio – this sounds really interesting.

  • Peter F

    I think plants like this and similarly sized wind farms in the 10-25 MW range are the future. They can be connected to the 22/66 kV distribution grid and most of the power can be sold locally improving resilience and reducing transmission losses. They can be matched with some storage and or biomass/ mini hydro etc so that 80-90% of power is generated locally. If they are owned by a local co-op all the better, keeps money in the district and improves the local economy.
    This farm will supply enough power for about 3,000 people and local businesses so a town like Griffith needs 5 of them each combined with three or four 2.4 MW wind turbines using common grid connection infrastructure

  • Graeme Harrison

    I love the concepts in the project – using a system that is quick/easy/cheap to install a good number of solar panels.

    BUT, I do wonder about designs seeking to optimise land use. Land is incredibly cheap in dead-centre Queensland. Adding maintenance/cleaning access walkways (wide enough for a ride-on mower or quad-bike with pressure-sprayer or spare panels in quad-trailer) might use a tiny amount of additional cheap land, but make long-term maintenance much cheaper. It also avoids health issues of crawling under array to unscrew from below.

    MIT did a study a few years ago, finding that the most efficient wind turbine arrangement for windfarm limited to any given hight was a crystal-lattice type array of vertical axis turbines. This could give the highest energy per acre/hectare. But I suggest this is a meaningless parameter to optimise for. Most wind farms are still spaced along ridges, because the turbines do not ‘consume’ the land, but grazing etc can still occur between them.

    Similarly, for installation systems, I think the optimisation should be for lowest cost of installation/maintenance over the expected life of the project, not per hectare. That would tend to provide for easy maintenance access.

    I also worry about large flat surfaces ‘tied’ to ground by only modest structural elements. Whirlies can exert huge upward forces as they pass over such a structure, sufficient to rip sections of roof from all-but-the-best-constructed farm sheds. Gaps between rows of PV panels allow that instantaneous 100kph+ wind to be sucked in from around, without lifting the large/flat connected surface shown in this installation.