Virtual Tracker panel arrangement

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Re: Virtual Tracker panel arrangement

Postby Gordon-Loomberah » Tue Apr 16, 2013 8:03 am

I've been thinking a bit more about the Virtual Tracker panel arrangement and realised that having the top and bottom of the panels horizontal is the equivalent of flat mouted panels- ie best for summer, but not so good for winter. In addition to having the panels facing 30deg above the E and W horizons, the panel should ideally be tilted by your latitude in the N-S direction. A typical 20degree sloped N-facing roof would be good for Qld, but further south a steeper tilt would give better winter performance. Being able to adjust the tilt for summer and winter would increase output, just as it does with N-facing arrays.
I have tried to do some more tests recently now the sun is well north of the celestial equator, but cloud keeps stuffing things up :(
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Re: Virtual Tracker panel arrangement

Postby Tracker » Tue Apr 16, 2013 10:06 am

Poundy wrote:I think Gordon was only advocating this for grid-connect scenarios where you need to cancel out your background usage rather than export and earn nothing from it. I think with charging batteries you still want to maximise that across the day, which would imply N facing.

The simple bottom line is that it's all horses for courses..
The concept of spending lots on panels and use them less efficiently, to achieve a controlled power generation, has to be kept in perspective. There is enough to contend with, with shadows and clouds and heat and panel inclination and, and, and.

There IS a practical application for battery systems, where the goal is to use a minimal battery capacity, and basically USE the solar power for the home... ie a solar supplemented system.. one where you want to seriously change your imported power usage.

With a minimal battery capacity and VT panel arrangements, you can have the best of both worlds.
Grid supplementation and a degree of autonomy.. ie. Keep those batteries fully charged all day and ready for any grid disruption..


IMAGINATION.. pure imagination as to how you can adapt the concepts, for max benefit ..
Gordon-Loomberah wrote:Being able to adjust the tilt for summer and winter would increase output, just as it does with N-facing arrays.

Oh, to have the space... it's hard enough adjusting the North facing panels,without worrying about the e/w ones.

I am afraid that when it happens here, they will be fixed at something like 25deg.. not optimum by any means.
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Re: Virtual Tracker panel arrangement

Postby Gordon-Loomberah » Tue Apr 16, 2013 10:14 am

Tracker wrote:The concept of spending lots on panels and use them less efficiently...


What, you mean like fixing the panels in place facing north, instead of getting maximum output with a tracker? ;)
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Re: Virtual Tracker panel arrangement

Postby Tracker » Tue Apr 16, 2013 12:10 pm

Gordon-Loomberah wrote:What, you mean like fixing the panels in place facing north, instead of getting maximum output with a tracker? ;)


Oh how nice it would be.. I still wish that I had been able to go ahead with a real tracker.. :cry:

If I do the VT thing, the neighbours will be really talking anyway.. I'm sure they think I am strange.. :idea: .. No comments now... :oops:
They comment--- "are you trying to power the suburb.. :?: .."

As we know - Horses for Courses..
The Mechanical Tracker is simply the BESTEST option for power/M2
The fixed North are great for producing the maximum for generous Feed-In-Tariffs..
..great for MAX charge to a battery bank..
The VT is especially beneficial when you have the option of a small additional NET feed in system, so most of your background power is covered by Solar..
So much will change when those generous benefits are taken away.

I'm vacillating between a small NET E/W VT GRID system and a battery system (Grid Supporting), but then I wonder about an alternative one..
ie.. house lighting and small power circuits, and a matched SOLAR system..
PV's feeding some heavy capacitors and smaller Inverter, and a fast A/C transfer.. ie.. power what you can when you can and no expensive batteries on THAT system..
Would be great for the FINAL Off-Grid system, where you can minimise daytime use of the real battery system..

Not tremendously "Solar" efficient, but use full when this system is distanced from the main Battery Plant.
ie. no energy efficient way of getting the VT power to the battery..

Sought of A/C coupling, as is being discussed more and more..
..
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Re: Virtual Tracker panel arrangement

Postby Tracker » Tue Jun 25, 2013 4:14 pm

....
The idea is to place panels tilted up 60degrees, ie pointing 30 degrees above the horizon, facing east and west, in order to get a fairly constant output throughout the day...


Gordon.... to add color to the picture
, what do you see as the result of laying the panels down more .. eg. Say a typical roof angle of 30deg.
I am ignorantly assuming the 60deg gives the flattest response consistent with supplying a consistent power all day and that dropping them to the 30deg will give a more pronounced noon peak..
Will it give more overall power , thus improving any net FIT that one might get. .
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Re: Virtual Tracker panel arrangement

Postby Gordon-Loomberah » Tue Jun 25, 2013 4:39 pm

Yes less tilt will give a more pronounced solar noon peak output, and more total output. 60deg is best for even output throughout the day. Higher noon output is great if you are on a high FiT, but there's not much point doing it if they pay you peanuts or less.
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Re: Virtual Tracker panel arrangement

Postby Tracker » Thu Jul 25, 2013 9:12 am

.
Gordon, if one sought a general rule-of-thumb hint on optimum angle for their part of Australia, for the flattest E/W all-day response, what time of the day, would you think to use to manually adjust...?

Eg 1500.... adjust till sun is perpendicular, and this should be optimum for flatter response..

Am I explaining myself logically.. :?:
..
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Re: Virtual Tracker panel arrangement

Postby Gordon-Loomberah » Thu Jul 25, 2013 10:29 am

After some thought in recent months, I think for best year-round performance, assuming the number of sunny days/month is reasonably consistent, the best position for the panels would be to face the panels at points on the celestial equator, at points equal to your latitude north of due E and W.

For example, if you were at 33.5deg south, then the panels should be tilted at 30degrees, and point at azimuths 56.5 and 303.5.

Of course, this will not fit installed flat on most house rooves, so ground mounting is best, but if you have NE and NW facing 30 deg slope rooves, then winter production is favoured, and if you have E and W facing, then summer production is favoured. Less slope (ie panel tilt) means that output wont be as near to flat as the ideal, there'll be a bit of a peak around solar noon. I haven't looked at it in detail yet, but I think there will tend to be a a bit of solar noon output peaking in winter too, as the sun will be less than 60degrees from face-on to the panels for a bit. If there was any chance of a cloud-free day I'd do some tests... maybe sometime in the next few days might be ok.

Once I get my new alt-az tracker up and running, I am thinking of converting the existing large tracker to a Virtual Tracker, with the ability to do seasonal adjustments, ie more than my latitude tilt in winter, and less tilt in summer.

So, on the March equinox, point them at the sun at 8:30am, and 8:15am on the Sept equinox.
In the afternoons on the equinoxes,15:25 in Sept and 15:40 in March. A few days either side wont make much difference, but the time should be within +/- 5 mins... but it is easy to buy a cheap clinometer to measure tilt, or use a spirit level and a suitable 30-60-90deg triangle. I'm sure you can work it out ;)
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Re: Virtual Tracker panel arrangement

Postby karlajensen » Thu Jul 25, 2013 9:05 pm

I copped a couple of plugs in this thread, so here's my 2c.
1)roof pitch changes are expensive (tilts), panels are cheap.
work out the array based on a split East/West as Gordon suggests based on YOUR roof.
if pitch is low, add more panels.

My system runs a 2kW (in reality a 2.2kw as i force cool it) inverter with ~4.5kW panels 8 E , 8W, 8Nth.

my observations including experimentation with > inverters!
A) a 3.6kw inverter would be ideal -little or no clip.
B) 2.2kW has at least some clip for 9 months of the year
c) Clip actually equates to ~1.4kW for 4hrs a day and ~6 months of the year at best ie just 1MW.
thus.....ideal 4MW (E/W arrays)+2.4MW(Nth Array) 6.4MW-1MW thus 5.4MW from a 2kw inverter.

this is the most extreme case you are ever likely to see and given 2kW Nth facing on 2kW inverter would yield
~3.3MW its worth more than $1000 a year in FIT, becomes a no-brainer given 190/200W panels are now well under $200 a pop.

Even more extreme is the 2.2kW i have facing SE! -terrible in winter but great in summer!
8E + 8W + 8Nth Garage CMS2000-1 with ~4500W in 3 strings of 8.
Fronius Galvo 3.0 inverter with ~6.6kW panels
12x ZNShine + 12x 180W Solarfuns both NW + ZNShine 12x190 facing SE.
Edwards Solar Hot water


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Re: Virtual Tracker panel arrangement

Postby evadsiv » Wed Aug 07, 2013 12:35 pm

Gordon,
Is that your site advertising Virtual-Tracker tm.
If so Gratz on taking the concept further.

Is there any tables that will let me work out approx output for Virtual tracker at my Lat given different roof pitch and azimuths. Or just go back to Sin and Cos tables?
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