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Tracked Array

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Started 2 years ago by IAEA
Latest reply from photonthief

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IAEA
Member

Hi all,

I'm new here so be gentle with me.

I would like to ask the question as to why there is not an 'explosion' of tracked array PV sys. around instead of fixed installs that one sees commonly?

I have been following a tracked 1.5kW array in the NE of Vic. that today offered this: "Daily Yield: 11.87 kWh". Compare this to a 2kW sys. here in Melb. (Eastern suburb) that did this today: "Solar Today 8.32kWh"

This 1.5kW sys. has produced: "Total Yield: 6128.81 kWh" since Aug. 2007.

Why is there not more of these tracking array to maximise a ROI here in Melbourne/Victoria?

If on the other hand it is more econonical to install a fixed array, what additional watts would one need to match this 1.5kW sys. in its Total Yield avg. out for 1 yr.?

Do any members here have a link to live data (streaming) of a 1.5kW sys. in Melb.?

Solar Data
2010
Last Power Reading: 0 W
Total 60W Bulbs: 0
Daily Yield: 11.87 kWh
Total Yield: 6128.81 kWh

--------------------------------------------------------------------------------

Current Conditions
Solar Power 0W
Solar Today 8.32kWh
Total 528 Watt
Pool 16W, Main 512W
Last hour usage 0.55kWh
Room Temp. 28.0
Last record 2010-03-17 19:32
Solar Information
17/03/2010
Dawn 06:15
Sunrise 07:17
Solar noon 13:28
Sunset 19:37
Dusk 20:39
Inverter Last Info
Input Voltage 253.78
Input Current 0
Input Power 0
Grid Voltage 244.18
Grid Current 0.52
Grid Power 0
Grid Frequency 50
Conversion Efficiency 0
Inverter Temperature 31.12
Booster Temperature 30.97

Cheers,
IAEA

Posted Wednesday 17 Mar 2010 @ 8:59:39 am from IP #
Russell Moore
Member

My guess is that the KISS principal is at play here. A two axis tracking array is certainly more efficent than a fixed array. The best I could see was a 25% boost to output.

The negative side to trackers would be, 1) cost, 2) complexity, 3) upkeep, 4) shading, of other panels, and thus more spacing is needed between the panels. You could offset the extra cost in the tracker system by adding extra panels to a fixed array system. Maybe someone who has a tracker system could enlighten us...

Also most suburban installs are on top of roofs, and fixed angle arrays are less obtrusive.

Posted Wednesday 17 Mar 2010 @ 9:15:36 am from IP #
dymonite69
Member

A 10m2 array weighing over 150kg driven by motors tracking in two dimensions 10000 times over 30 years without ever being blown off the roof by a strong wind gust.

Posted Wednesday 17 Mar 2010 @ 10:11:37 am from IP #
peterhawkes
Member

I am working with Solatraka to put together a packaged price for Solar Array + Tracker on the Gold Coast Queensland. If you have an interest in this product, hit me up at http://www.peterhawkes.com/off-grid so I can get some orders in.

I'm checking to see if this can be mounted on a roof? Wind Tolerance?

Posted Wednesday 17 Mar 2010 @ 9:27:36 pm from IP #
ghostgum
Member

Tracking costs extra money, and is one more thing to break down. It would make more sense if you had lots of space (i.e. not the city), and needed more electricity in the morning or late afternoon.

Posted Thursday 18 Mar 2010 @ 12:50:00 am from IP #
IAEA
Member

ghostgum writes...

"Tracking costs extra money,"

They do cost extra money. I can secure one to cater for a 1.5kW sys. for AUD$2,900 delivered. I will have to erect it though. I want to be able to match a 1.5kW tracker that is pushing out approx. 14kW(h) on a good day in the NE Vic., so what no. of additional panels would I require if it was installed as a fixed install here in Melb?

Cheers,
IAEA

Posted Monday 22 Mar 2010 @ 12:17:26 am from IP #
ghostgum
Member

Try keying in the data to
http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/
Select "Southwest pacific", AUS Melbourne, Start PVWATTS for international sites.
There are options for fixed tilt, 1 and 2 axis tracking.
It looks like the tracking will increase annual output by 19% for one axis and 23% for two axis tracking.

So the equivalent would be a 1.875kW fixed tilt system instead of a 1.5kW tracking system, with two extra fixed tilt panels at about $1000 each.

Posted Monday 22 Mar 2010 @ 12:35:10 am from IP #
IAEA
Member

ghostgum writes...

"So the equivalent would be a 1.875kW fixed tilt system instead of a 1.5kW tracking system, with two extra fixed tilt panels at about $1000 each. "

Thanks very much for the reply. Now, given that the tracker is operational for a max. of 15hrs./day in the NE, and beyond the Great Divide the temp. is more favourable than down here in Melb., what additionl panels are necessary to cater for the peak sun hrs. that Melb receives during Mar.? From a Govt. site it is 5.2hrs. per day for Mar.(avg.)? The avg. for Melb. for a yr. is 4.6hrs./day.

Hope I have this right? Please correct if I am wrong.

Cheers,
IAEA

Posted Monday 22 Mar 2010 @ 12:46:31 am from IP #
Russell Moore
Member

IAEA, it is almost impossible to give you an exact answer to your question. The amount of sun you will receive is so variable, I believe that even trying to compare another array in an adjoining suburb is fraught with difficulties.

I see my output jump up and down like a yoyo on cloudy days, from anything as low as 1,200w up to 4,300w in a matter of seconds, as the clouds pass overhead, and we go from heavy cloud to full sun.

I believe ghostgum has it about right with the two extra panels, amd don't forget that you will need extra space for the tracking panels as well as for the extra fixed panels.
Tracking panels will shade each other if the spacings are wrong, fixed panels don't.

Add to all this the simplicity of the fixed panels, and the complexity of trackers, and I know where I would go.

Posted Monday 22 Mar 2010 @ 1:17:34 am from IP #
IAEA
Member

Russell Moore writes...

"The amount of sun you will receive is so variable, I believe that even trying to compare another array in an adjoining suburb is fraught with difficulties."

You are so, so right with this statement. This is why I requested a tracker here in Melb. that I could use as a reference against a 2kW fixed install I have access to (Melb.) insofar as extracting real time data.

What would those two additional PV panels amount to in watts? Would that be 350, 420 or 600watts?

This is all so confusing, I can tell you.

This 1.5kW sys. absolutely eats a 2kW roof install here in Melb. consistently on a daily basis. I would dearly love to replicate its performance here in the outer East.

Cheers,
IEAE

Posted Monday 22 Mar 2010 @ 1:44:41 am from IP #
ghostgum
Member

North East Victoria is north of the divide, and consequently gets more sun than Melbourne. A PV system in Wodonga would do much better than Melbourne, and Mildura (North West Victoria) would do even better.

It's been sunny most of the morning in the Melbourne CBD, but my solar system 20km away has been mostly under cloud before midday. As the other Russell said, it varies by suburb.

To compare two sites, get the solar insolation data for NE Victoria, and compare that with Melbourne. Here is one graph of Australian solar insolation
http://www.bom.gov.au/jsp/awap/solar/index.jsp
http://www.bom.gov.au/sat/solrad.shtml
I haven't yet found how to access tabulated data for specific sites.

I was suggesting that a 1.9kW system (10x190W panels) with fixed tilt would give about the same output as a 1.520kW system (8x190W panels) with 2 axis tracking. A budget 1.520kW system is about $7000, so increasing by two panels to 1.9kW would be cost about $2000 more. This is cheaper than the $2900 you mentioned for the tracking equipment.

Posted Monday 22 Mar 2010 @ 2:31:38 am from IP #
Russell Moore
Member

Was just speaking with IAEA, ah, good old Skype.... he has access to some low priced high output 300w Sunpower panels which could be installed as one unit, hence no overshading, and probably only one tracking system, so only five are needed for a 1.5kw system. Might be an OK way to go..

I still favour the KISS way though!

Posted Monday 22 Mar 2010 @ 3:00:07 am from IP #
IAEA
Member

Many thanks to the both of you in the main for responding against my initial enquiry. Much appreciated.

Have a lot to injest re: PV and an install here in Melb. Not really happy with the FiT as being a nett programme here in VIC. Did all know that, that additional AUD$0.06/kW(h) can be recinded by the retailer (TruEnergy) in my case by the provision of a formal letter to me giving me 10 days notice that it is to occur? This is not good as far as I'm concerned.

The below is some additional data comparing a fixed install of a 2.16kW sys. in Melb. and the 1.5kW install.

On the 16th. the 2.16kW did 11.2kW(h) and the 1.5kW did 12..63kW(h) ....... impressive.

Cheers,
IAEA

Posted Monday 22 Mar 2010 @ 3:33:26 am from IP #
ghostgum
Member

The 11.2kWh for 2.16kW system is 5.18kWh per kW of panels.

On 16 March, my 4.67kW system 24km SE of Melbourne CBD generated 24.02kWh, or 5.14kWh per kW of panels. Very similar to the 2.16kW system. That was a good sunny day according to my graphs. My panels are at only 7 degrees tilt.

I'm not fussed about it being a net feed-in tariff, because my system easily exceeds our daytime standby power use. I'd be concerned if I had a 1kW system.

Posted Monday 22 Mar 2010 @ 4:42:51 am from IP #
IAEA
Member

Russell Moore writes...

"he has access to some low priced high output 300w Sunpower panels ......"

An error had been made re: the cost: The 210W panels will cost AUD$1,000 each, GST incl. So for a 1.470kW sys. - cost will be AUD$7,000. The 300W jobs are AUD$1,480 each.

Cheers,
IAEA

Posted Monday 22 Mar 2010 @ 6:44:22 am from IP #
Russell Moore
Member

So $1,480 x 5 = $7,400 for the 300w panels + $2,900 for the tracker = $10,300 plus added costs to install it all....maybe around $11,000 all up, minus RECs...

Posted Monday 22 Mar 2010 @ 7:51:33 am from IP #
ghostgum
Member

Plus the cost of the inverter.

Replace the $2900 tracker with $2960 for the two extra 300W panels, and you will get more output, although you will also be paying another $500-1000 for a higher power inverter.

Posted Monday 22 Mar 2010 @ 9:59:20 am from IP #
IAEA
Member

ghostgum writes ...

"I'm not fussed about it being a net feed-in tariff, because my system easily exceeds our daytime standby power use."

How is your sys. performing now that we are in autumn, and heading towards winter? We still have three mths. to go before winter concludes.

IAEA

Posted Friday 28 May 2010 @ 2:35:12 pm from IP #
Russell Moore
Member

Each 'PV solar season' is 13 weeks, spread 6.5 weeks either side of the two solstices, and equinoxes. Thus for the 'winter' season, which we are already in, we are just over 3 weeks out from winter solstice, when the amount of available sun will start to climb again, albeit very slowly at first.

Thus we will be in the spring 'PV solar season' in about 10 weeks.

Hard to say how well my system is working now as we have had a lot of rain and cloud lately, but going by recent outputs when it was sunny I would guess this: Max output winter season 4kWh per 1kw, spring/autumn 6kwh per 1kW, Summer 7kW per 1kW? yet to go through a summer season...

Posted Saturday 29 May 2010 @ 2:14:36 am from IP #
dymonite69
Member

It's fairly easy working out the changes in output over the year. Summer to winter insolation varies from 2 to 4 fold depending on your latitude. Closer to the poles, the greater the variation. At the equator it remains constant.

I have been assiduously monitoring our solar hot water boosting (thus estimating the energy output of the system) and mapped it against monthly insolation over a year. The two sinusoidal (or more correctly cosinusoidal) curves are in near perfect synchrony.

Posted Saturday 29 May 2010 @ 3:01:08 am from IP #
ghostgum
Member

IAEA,

The month of May has been pretty good in Melbourne. I'm averaging about 10kWh per day generation (off a 4.5kW system), which is above the expected 8.3kWh per day.

In the last 10 days since the cogen meter was installed, I've been generating 9.4kWh per day and exporting 6.6kWh. Sunny days I export 75% of production, bad days I export 40%.

I did discover that 6 weeks before the winter solstice, some of the solar panels are shaded by a tree in the adjacent school. This lasts for an hour, starting just after 2pm. The output from one panel string/inverter is hit hard by this shading (output reduced from 900W to 90W). The other panels are in two strings on a separate inverter and while also receiving lesser shading, is not impacted as much. I've not been home on a sunny weekend afternoon to investigate in detail. I suspect that either one of two strings is being shaded, reducing output to half, or those solar panels have a better bypass diode arrangement.

Posted Saturday 29 May 2010 @ 3:18:43 am from IP #
IAEA
Member

ghostgum writes ...

"I'm averaging about 10kWh per day generation (off a 4.5kW system), which is above the expected 8.3kWh per day."

http://www.yourhome.gov.au/technical/fs67.html

From the offered Govt. website the peak sun hours averaged out pa for Melb. is 4.6. If your sys. is 4.5kW, then your sys. "should" offer you as an avg. 20.7kWh and not what your are receiving at 10kWh (avg.).

Is this correct, or am I interperating the chart wrong? Are you losing AUD$7.062/day from not generating (avg.) 20.7kWh/day right now?

IAEA

Posted Saturday 29 May 2010 @ 5:21:38 am from IP #
IAEA
Member

I have this wrong as for May, the avg. is 2.8 (PSH - Peak Sun Hours, Melb.) and at that level the return should be 12.6kWh (avg.).

So, the loss is not what was stated at $7.06, but $1.72/day for the mth. of May. I think I have this correct.

IAEA

Posted Saturday 29 May 2010 @ 5:44:33 am from IP #
ghostgum
Member

I was using PVWatts v1 for the calculation, using 7 degree pitch.
http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/
I still got the figures slightly wrong - it should be 8kWh per day for my system . 31 days in May, not 30. My system is actually 4.67kWp, not 4.5.

Using your figures, you need add another derating factor of about 0.77.
http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/derate.cgi
Then 2.8 hours * 4.67kWp * 0.77 derate = 10kWh.
Then we add another factor of about 0.8 to account for the difference betwen 7 degree tilt and the preferred 28 degree tilt (latitude - 10 degrees).
That gets us back to 8kWh per day, the same as before.

Posted Saturday 29 May 2010 @ 6:00:11 am from IP #
IAEA
Member

Ah yes!!! Had not allowed for the derating.

IAEA

Posted Saturday 29 May 2010 @ 6:19:03 am from IP #
IAEA
Member

< Daily Yield: 11.87 kWh
Total Yield: 6128.81 kWh >

Six months ago I started this thread and the then total was 6128.81kWh. The most current fig. as of today is 7190.54kWh.

This is a difference of 1061.73kW over six months.

This calculates out to 5.8338kWh/day and is 3.8892kWh/kW.

This has been achieved at a Lat of -36.12578. Would like to know as to other fixed installs and what kWh's has been achieved at Lat -36.12578 or in Melb. at -37?

If taken as a 5kW sys., a fig. of 3567.4853kWh would have been achieved over a six. mth. period. If a 10 kW array - 7134.9706kWh's.

Cheers,
IAEA

Posted Friday 17 Sep 2010 @ 12:25:31 pm from IP #
matas
Member

Sorry to revive an old thread.
It's just that I have read references to a "tracked 1.5kW array in the NE of Victoria",
mentioned by the original poster, in a few different forums.

Just wondering if anyone has links or more info on this system ?

I have become interested in tracked PV arrays, even if they are impractical.

Posted Sunday 19 Sep 2010 @ 5:43:57 am from IP #
thatmosis
Member

A tracked array can be installed by a DYIer. The cost can be kept to a minimum and the circuitry can be easily made up from bits and pieces purchased from a local electrical shop, ie Dick Smith or on line. Welding is a requirement but with the advent of gas less welders and ease of operation anybody can become proficient enough to produce the stand etc.The one i have the diagram for uses a car window winding motor as its motor source and relies on a photoelectric cell to trigger the movement. If anybodies interested i will have a look in the next few days in my archives for the diagrams and circuits.

Posted Monday 20 Sep 2010 @ 1:44:10 am from IP #
matas
Member

Thanks Thatmosis, I was interested in building a tracker one day.
I'll probably never achieve it though, because it seems a difficult job.
Good tip about using the car motor.
I have done a lot of amateur welding, but only have a stick welder, not a MIG.
I was thinking of using a computer program to calculate the suns position and drive the tracker that way.

Posted Monday 20 Sep 2010 @ 4:58:18 am from IP #
Benny
Member

IAEA, your figure of 3.9kWh/kW/day sounds about right for Lat 36deg and over winter. Plus I heard you've had a lot of rain over east this winter.
I'm in Perth, Lat 32deg and currently getting 7kWh from a 1.5kW array on a completely fine day. Average over last 6 months 4.9kWh or 3.2kWh/kW. System faces NE though.
Energy matters forum has heaps of data on typical outputs from lots of systems.

Posted Monday 20 Sep 2010 @ 6:16:55 am from IP #

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