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I have installed my 8 panels on a solar tracker I built and ..  I find that where I live I get up to 55% extra power from the same panels.
Would like to know if someone less also did this and what they are experiencing.

I designed the bearings, frame, cpu and.
It is amazing to see the difs between non tracker and tracker.

 

STrack.jpg

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1 hour ago, plonkster said:

I think the concensus here is if you build your own and if you like doing that sort of thing, or if space is at an extreme premium, then it makes sense. For everyone else it is cheaper to just add more panels :-)

Plus one on that!

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Many thanks for the comments.

I can not get the same results with the same $ spend on extra panels as on the tracking system.

The tracking only galv was expensive else I need an addition 6 panels to get the same charging rate.
Tracker and all my system is at +/- R45K 4 x 200A solar tracker  management system for home 8 260W panels and 3 - 5 Kwatt inverter.
The frame for my house I was quoted R 3800 and the tracker cost R 5300 for 16 panel unit and will give me 520 amps per day.

Effectively for R1500 I got between 40 - 55% more power.
I harvest more than 260 amps per day.

In the summer I get more than 300 amps per day between 40 - 55% more effective.
No MPPT no ....
Very simple.

today.png

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FWIW.

With my recent introduction to CoC's for panels, all panel wires must be as per new regulation specs, preferably enclosed, although the new ones can lie in the sun. But, we all know the sun wins in the end. 

And earthing the panels ... whole new subject, spakies differ in their approaches. One said if they are in doubt, they approach a engineer.

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15 minutes ago, Erastus said:

I harvest more than 260 amps per day.

Amps is a rate of flow (1 coulomb charge per second). So normally you'd multiply them by hours to get back to an amount of electricity rather than a flow rate. And then you have to multiply them by the voltage at which the work was done to get a real idea of how much energy is involved. So sadly that line makes no sense at all :-)

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17 minutes ago, plonkster said:

Amps is a rate of flow (1 coulomb charge per second). So normally you'd multiply them by hours to get back to an amount of electricity rather than a flow rate. And then you have to multiply them by the voltage at which the work was done to get a real idea of how much energy is involved. So sadly that line makes no sense at all :-)

It is simple.

People like to talk watts P P = I X E.  But if you have a messed up impedance matching RtI != TtL (maks power tranfer) then you make use of electronics to do the tricks and induce losses which is ignored. If you want to calculate  at low V 45V or full charged 57.8V or when equalizing 60V it all give different Kw. But no matter what you or I do a solar panel can only giv  mx amps from solar panel.
The current I am getting from now +/-  7 amps at +/- 7H30 to 8.5 amps peak solar - 7 amps +/- 18H00. That == 9H30 or +/- 75 amps per string. Therefore @ 45V =  3.3Kw or 4.5Kw @60V. Therefore I am running @ 98 - 99% power transfer. That is not possible with fixed array. Fixed array over 12 monts between 45 - 55%. Solar tracking very close to 100%

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31 minutes ago, Erastus said:

messed up impedance matching

Yup, that bit I understand. Normally the voltage the panels work at is at least 30% higher than the battery voltage (36-cell so-called 12V panel really makes 18V at Vmp), so you lose a third of the power by pulling them down.

But if you can design the string voltage to be closer to the battery voltage, and keep it there (which I assume is what you do by physically tracking the sun), then this loss will be much lower than 30%. I would be very surprised if it does efficiencies of 98%, but I suppose it depends on what your benchmark is. If your benchmark is "that which I would have gotten with a fixed array and an MPPT", then yes, you might be able to do almost as well with a tracker.

(I'd still pick the MPPT... no moving parts... at least if the inductor is properly glued down!).

Tracking simply keeps the insolation closer to 1000W/square meter (so your power curve is more square), but I'm confident an MPPT will still improve overall energy harvest above that (ie tracker plus mppt will do even better). In theory, if the impedance is already close to a match, the MPPT would PWM at a very high duty cycle approaching a direct connection anyway.

Of course you may want to save the cost of an MPPT, which is a different argument.

Edited by plonkster
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42 minutes ago, Erastus said:

8.5 amps peak solar

Pretty typical.

42 minutes ago, Erastus said:

75 amps per string

Woah how did you get that!? Oh hang on, you multiplied the hours with the current, so it is 75Ah (amp hours) per string? That makes more sense :-)

42 minutes ago, Erastus said:

45V =  3.3Kw or 4.5Kw @60V

and there's the voltage inefficiency bit illustrated clearly. If you designed the array to have a Vmp of 60V (that's some pretty gnarly thick 35mm cable), then the MPPT will run it at 60V the whole day and you will get 4.5KW regardless of what voltage the battery is at. Plus a 2% loss or so on the cable (1.2V) times 75A, that's another 90W lost on the cable, which you can more than half by doubling the voltage of the array.

Yeah, I'm not convinced. It might be a good alternative, but I'd still go MPPT :-)

Edit: Oh hang on again... You mean at 45V it would work out to 3.3KWh and at 60V to 4.5KWh! See the importance of using the correct units? I literally have no way of following this.

Edited by plonkster
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MPPT does not allow for the angle of the sun and can loose up to 18% . Only to do a in-between-er for a system badly designed.
Please I am not trying to promote a tracker. I live right on the west coast and the North West hits me right on the wrong angle every now and then my veranda disappears.  For that reason I did not dare to use the "normal" solar "frames" Mine is made of 100mm x 50mm steel and can handle 16 panels. I got engineers to do the checking of wind load plus safety and COC simply the storms are tough.
Last year I had +/- R90K storm damage but the solar worked 100%.
With the strong frame that was not a bad cost of R4800 I thought let me do a tracker. Then I saw why it is so expensive and I designed all the metal work bearings and voila it dropped the costs drastically.
I can not buy extra panels at the same cost to give me the same power than with the tracker. So I Have 3 phase power and City approved 9Kva system.
That gives me my money back and makes it worthwhile to put back in the grid.

I am waiting for my inverters and then I can can start pumping back. I must be honest there are three "guys" involved in the process at CoCT they are terrific re this.
 

WindFactor.pdf

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5 minutes ago, Erastus said:

I must be honest there are three "guys" involved in the process at CoCT they are terrific re this.

YES!!! They are not out to "get you" or anyone for that matter, are they?

Ever helpful and quite knowledgeable about going solar and why the regs, right?

Edited by Guest
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4 minutes ago, plonkster said:

Pretty typical.

Woah how did you get that!? Oh hang on, you multiplied the hours with the current, so it is 75Ah (amp hours) per string? That makes more sense :-)

and there's the voltage inefficiency bit illustrated clearly. If you designed the array to have a Vmp of 60V (that's some pretty gnarly thick 35mm cable), then the MPPT will run it at 60V the whole day and you will get 4.5KW regardless of what voltage the battery is at. Plus a 2% loss or so on the cable (1.2V) times 75A, that's another 90W lost on the cable, which you can more than half by doubling the voltage of the array.

Yeah, I'm not convinced. It might be a good alternative, but I'd still go MPPT :-)

Edit: Oh hang on again... You mean at 45V it would work out to 3.3KWh and at 60V to 4.5KWh! See the importance of using the correct units? I literally have no way of following this.

45V when batteries are flat not PV voltage but gives different Kw calculation use for demo. If I am a salesman I use 60V @ 8.5A. But if the Vbatt is 45 then you still get 8.5A but the Kw is different.  Therefore I use amps not Watt's.
You go for MPPT but get try and equal harvest INTO THE BATT you can not match that if your RiT = RlT. MPPT takes voltage and push it through a set of transformers. to start there the losses starts.

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3 minutes ago, The Terrible Triplett said:

YES!!! They are not out to "get you" or anyone for that matter, are they?

Ever helpful and quite knowledgeable about going solar and why the regs, right?

My experience with CoCT make me understand the actions of TmcV

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1 minute ago, Erastus said:

Therefore I use amps not Watt's.

Can't use only the amps when calculating efficiency, since the bulk of the inefficiency (in almost all areas) is due to doing the work at the wrong voltage.

For example, the main reason lead acid batteries are so inefficient, is because you put 100Ah into them at 14.2V, and then take it out at nominal 12.5V. So 1420Wh in, and 1250Wh out, or 88%. Without even looking at any other losses. Lithiums spend almost their entire life at 12.8V-13.2V (using a 12V example), so 1320Wh in, 1280Wh out, or 96%. Do the math again for "Edison cells" (Nickel-Iron) and it gets even worse.

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18 minutes ago, Erastus said:

My experience with CoCT make me understand the actions of TmcV

My experience with CoCT make me understand the actions of TmcV
I think one has to understand:

  1. Technical stave helpful and pleasant
  2. Building inspectors arrogant and not so helpful
  3. Admin and Fin  can be summarized by arrogance = 1 / knowledge

The last two are the problems not the technical people. When the fin director send you a insulation certificate for a calibration certificate and does not have the ability to understand the difference then you problems start.

Technical staff Mr A de Jager superb in BeVille "Morgan Claasen inspector" superb Eunice Lugalo superb Bonginkosi Majavu
 superb Joy-Ann Southgate superb.

It is super to deal with them. They tell you straight what is required. Guide you where to get. help you when forms are wrong and with procedures.
The people in aircon offices with the exalted egos they are the problems

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10 minutes ago, plonkster said:

Can't use only the amps when calculating efficiency, since the bulk of the inefficiency (in almost all areas) is due to doing the work at the wrong voltage.

For example, the main reason lead acid batteries are so inefficient, is because you put 100Ah into them at 14.2V, and then take it out at nominal 12.5V. So 1420Wh in, and 1250Wh out, or 88%. Without even looking at any other losses. Lithiums spend almost their entire life at 12.8V-13.2V (using a 12V example), so 1320Wh in, 1280Wh out, or 96%. Do the math again for "Edison cells" (Nickel-Iron) and it gets even worse.

How do you charge the batt what does the PV deliver?

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7 minutes ago, Erastus said:

I am revering to harvesting. Then the formula of max power transfer is the most important one one can get.

Agreed, so my one array makes 8.5A at 115V. My MPPT drops that to around 35A at 26V where my batteries live most of the time, around 95%. So the MPPT loses me around 5%, but some of that is because my array is a tiny bit oversized, typically I would expect 98%.

So clearly there is a bit impedance mismatch in this setup. Without an MPPT, I would have to use a different setup. 0.5V per PV cell at max power, generally speaking, so I'd have to somehow make up strings of 58 cells each (60-cell panels might be a close match). So the panels make peak power at 30V, at 8.5A, while the battery gets 8.5*26V (nominally for my LFPs). That's a loss of only around 35W (not bad heh?), or an efficiency of around 87%. I can get it better if I can make up 58-cell panels...

Now if I point them to the sun all day it might do just as well, perhaps better than the stationary one with the MPPT. But personally I'd still pick the MPPT, because the DC/DC conversion remains more valuable to me.

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87% not bad but compared to to 96 - 102% and the amount you paid for the MPPT.

That  proves the formula of Max P transfer 100% a coil transformer WILL have at least +/- 10% loss.
If we are talking of grid system it is 100% important to match PvV with Vbatt then you do not require a MPPT and you have 13% more power as you explained.
Maybe that is why my 3 -5 Kw system only cost R23000 and not the amount I was quoted.
Your explanation of the MPPT defines the money wasted in solar systems.
Of grid system FOR SAFETY the best voltage is 48V and that will be the best value for your $
Thank you for explaining why a MPPT is an unnecessary evil to have  :rolleyes:
If you are running at 26V and you are charging batteries you will for sure shorten the life of the battery

It is impossible to beat the cost of a well designed system.
The best inverter and solar system is one without mppt and charging cct and the best cost ratio as well.

MPPT is to compensate for a bad design. I play a bit in electronics and the more you design and add the bigger the cost, affecting reliability but veryseldom added value.

The old saying KISS is very important.
The reason why I use 48V you can not get killed by it. But 96 and higher will kill some one.
I understand a higher Vdc is more efficient than 48V but life is more precious than $
I do want to thank you for this nice conversation it is appreciated.

Edited by Erastus
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46 minutes ago, Erastus said:

That  proves the formula of Max P transfer 100% a coil transformer WILL have at least +/- 10% loss.

Well, it's a DC/DC converter, a so-called buck converter. It uses an inductor, a capacitor, and a "flyback" diode and/or active switch and runs it at 40khz (or more) using a PWM signal, and then by modifying the mark/space ratio of said PWM signal it adjusts the impedance. By using a closed control loop you adjust it until you hit optimum power, which is where dI/dV = I/V or dP/Dv = 0, if you want to get into the maths :-) So the efficiency will be in the order of that what other SMPS (switch mode power supplies) do, which is better than your typical iron transformer (a correctly sized iron transformer is already 90%-95% efficient). For the Victron kit this is known to be as high as 98%. It's extremely well understood technology.

This book has an entire chapter on SMPS design, which the authors have graciously made available for free.

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Plonkster,

Maybe I am struggling to understand English or maybe I am describing stuff incorrectly. I only have to go by what your statement.  A Iron core transformer has an efficiency of 90 - 95%. In other words it need 5 - 15% to step up or step down.  Thus if I use a panel of 8 amps then according to you the loss is between 5 & 10%.  Thus .4 - .8 amps is used (dissipated) in the core. Or you need 11 panels to do the same as I do with 10 panels. 

Is the maths wrong?

What do I miss understand when you are describing 98% efficiency means a loss of 2% or do I have it completely wrong. 98% is always less than 100%.

What part am I missing or misunderstanding?

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