powering trackers

Discussion about the MX60 Charge Controller

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Fritz
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powering trackers

Post by Fritz »

I'm converting throwaway C-band satellite dish mounts to carry PV modules. Small, but they TRACK.
I want to make sure I cannot damage anything by powering the actuator from the PV output - which is the MX input... it might confuse the MX a little? but no catastrophic reverse bias avalanche with smoke?
Thanks-
boB

powering trackers

Post by boB »

I would shy away from connecting things other than the charge controller to the panels if possible... The biggest reason for that is that the panel's open circuit voltage (Voc) reading as measured by the controller, (either ours or others), may not be as accurate with another load on the PV and might not operate as well as it would otherwise. Also, running off the batteries will ensure that there is enough juice to move the panel tracker to the correct position in lower light conditions.

You also don't want to take a chance on shorting the MX60 PV terminals if you can help it... just in case the tracker control got stupid or stuck or something.

bob [img]images/smiles/icon_biggrin.gif[/img]

>it might confuse the MX a little? but no >catastrophic reverse bias avalanche with smoke?
Fritz
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powering trackers

Post by Fritz »

I'd make a controller - using a 80c51 and a Dallas Semi clock chip (DS17285-5). wakes up, 8am, must be morning, go east array 1, go east array 2, go east array 3.
go to sleep. Wake up 10 am, move west a little
etc. Til sundown
So the trackers' presence on the line would be highly intermittent, giving the MX plenty of time to recover.

Powering from the batteries means another longish run of wire. This is a 12V system that was hurting from long wire runs between panels & batteries & was recently (FANFARE!) improved by configuring the PV to 24VDC and adding the MX.
Controllers running stupid, well yes, and us humans too. Gives me the novel idea of fusing the actuator motors.
Which all labor at different and varying speeds.
Could be mechanical (likely), might be - hence the original question - some intestinal upset in the MX.
I observe steady operation, gradual slowdown then sudden speedup to original rate.
I plan to use the feedback pulses from the actuators to keep track of where the thing is pointing.
Just having fun...
rdmcghie
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powering trackers

Post by rdmcghie »

Fritz,

Why not just power them from the batteries, which is what Array Technologies, the manufacture of Wattsun trackers recommends for their trackers? They even supply a DC to DC converter to reduce the battery voltage in 48V systems to the 24V the trackers need.

How are you going to make the old dish mounts track the sun?

Robert
wd8cdh
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powering trackers

Post by wd8cdh »

Hi Fritz,

I would still run the tracker on a small battery. You could run a very small cable from your main bank to a gelcell at the tracker.

Have you also thought of wiring your array for 48V? Even less wire loss than 24V.

Ron
boB

powering trackers

Post by boB »

Fritz, I think those actuators are 24V motors, aren't they? How were you going to make sure the motors don't get too high of voltage from the panels?
Just curious... BTW, I try to grab those actuators when I can too. I also like to play with C and KU band satellite stuff.
boB
Fritz
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powering trackers

Post by Fritz »

Yes i have thought of upping the voltage again. Which incidentally brings up this puzzler.
I have a motley collection of panels. Of one kind I have 3, which meant one got left out of the current scheme. Of the several other kinds I have just two. So I am still trying to figure a way of series-connecting in a way that is efficient. I understand all units in a series need to be matched or the series will default to the wimpiest output of the lot. I'd like some input on that. I'll gather the data and post.
...
I am not even sure of the motor voltage really.
Seems when I measured at the satellite receiver's actuator output it was more like 50VOC.
An entire storage system to keep the trackers happy , well, groan, maybe. Might as well run AC out there when needed.

Fritz kE6VDA
billvon
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powering trackers

Post by billvon »

>So I am still trying to figure a way of series-
>connecting in a way that is efficient.

The ideal way would be an individual PPT for each string. This could even be a boost converter rather than a buck converter, since the purpose would be to mount the PPT on the back of the modules and send a high voltage to the battery bank. The OK4U will sorta do this but is expensive - $2.5/watt - and intended for line tie instead of DC.

Or do a small PPT buck converter for each string. It could potentially be pretty cheap if power was kept low - say, <300 W. Then you could parallel them all onto a 24 volt bus to go back to the battery bank.

If all else fails, if you just join each panel at each node - i.e. do series-parallel - you can do a rough matching of the entire array. 10A is generally 10A as long as you don't mix amorphous and crystalline.
Fritz
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powering trackers

Post by Fritz »

OK the panels are
6 arco 16-2000 (xtal,33)
1 arco 16-2300 (xtal,35)
2 photowatt (xtal,35)
2 solec 13x47in (xtal,sq)
2 solec 17x47in (xtal,sq)
3 solavolt MSP43e33 (amorph)
2 solarex SX85U (amorph) 85w
4 siemens sp130-24p (xtal) 130w

So currently all the arcos and photowatt are two to a series, as is everyone else xept the siemenses which are 24v panels & the reason I sprung for the MX60 in the first place.
I am thinking of doing four to a series for the arco/photowatt,
series the 2 solarexes with the 4 solecs (paralleled in pairs, 1 fat & 1 skinny one )
which leaves out the solavolts. And mixes amorphous with crystalline.

what is the amorphous/ crystalline difference exactly in this scenario?
wd8cdh
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powering trackers

Post by wd8cdh »

Ouch!!! And I thought my mix was bad. I think that I would stick with a 24V system and put the odd modules on a 12V charge controller with seperate wires or try to get one more arco 16-2300 and one more solavolt MSP43e33. Or just put the third solavolt MSP43e33 in series with the single arco 16-2300.
Fritz
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powering trackers

Post by Fritz »

This may be a partial reply to my own question, and/ or a heads up for Bob-
This morning I went and did the tracking ritual.
Moved one array west to east.
Second array wouldn't move.
Relays (24VDC) no click.
Voltage at tie point 18.6VDC
Sure enough, back at the house Mx was pulling it that low.
Re-started it and the voltage went to 27 or so.

NOt sure if the confusion arose from the tracker voltage drop during sweeping phase.
I'll have partner watch the Mx while tracking is going on.
This is the first time in (calc from first post this topic) days that this has happened.
Yell if I'm getting close to voiding my warranty.

Cheers
Fritz KE6VDA
boB

powering trackers

Post by boB »

Fritz, What is your Panels Voc ? With/without the tracker motor hooked up? And Voc also when it's cloudy with actuator hooked up ?

You are combining Amorphous AND crystalline together ? There may be multiple maximum power points. When the panel voltage went to 27 volts after the 18 volt pulldown, do you mean that 27 V was the open circuit voltage with the actuator running? When/how often do the actuators get triggered to move? The MX60 may also be powering the actuator motor at times if the panels cannot supply the required current. Also, be careful not to short the PV terminals while the MX60 is operating, which is sounds like you're OK on.
boB
Fritz
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powering trackers

Post by Fritz »

first, an aside:
It would be nice if we could get some of the cutsie stuff out of the way of seeing what I am responding to
which I just did by copying your post into this tiny porthole.

                    
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Fritz, What is your Panels Voc ? With/without the tracker motor hooked up? And Voc also when it's cloudy with actuator hooked up ?</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">semi foggy/ cloudy this morning, 39.6 VOC, with actuator going it is 38.4 and 39.3 respectively (surprise!).( this is with batteries very full at 13.6V due to hydro, so the MX may already be trying to throttle back?)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">You are combining Amorphous AND crystalline together ? </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yes. Point me to a description of the potential problems this may create...

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">There may be multiple maximum power points. When the panel voltage went to 27 volts after the 18 volt pulldown, do you mean that 27 V was the open circuit voltage with the actuator running?</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">No, this was not open circuit. It reflects the batteries being charged at the newly calculated power point, and the actuators were off - in fact they seem to make little change unless there is very very little sunlight.

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">When/how often do the actuators get triggered to move?</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Currently, whenever I decide to run out there and move the panels. I won't automate this before making sure there are no overriding reasons not to (track). Ultimately, probably once every couple of hours should be plenty accurate. Running for about 10 secs. each, staggered.
Returning home is a longer haul. I plan on homing half the arrays in the evening, the other half in the morning (how elaborate can you get!)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">The MX60 may also be powering the actuator motor at times if the panels cannot supply the required current.</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">They DO run at 12VDC but slowly.
The MX handles this OK...? (the original question)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Also, be careful not to short the PV terminals while the MX60 is operating, which is sounds like you're OK on.</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I'll try not to verify .
The relay could be made to kick out on negative current flow... if that helps safety wise. It would nix running the actuators at night though.
Fritz
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powering trackers

Post by Fritz »

I am using mono-crystalline and poly-crystalline panels. Not amorphous. Sorry for the confusion
Brian Teitelbaum
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powering trackers

Post by Brian Teitelbaum »

Fritz,

I know that the Arco 16-2000s are only rated for systems of 50V Max (I have 12 of these modules on my house). I think that the 16-2300s and maybe the Solec modules are rated the same as the 16-2000 units. So I would advise you to stick with 24V as a maximum system voltage.
solarmon

powering trackers

Post by solarmon »

Hey Fritz! This MX contoler solves one big problem for me in it's voltage drop capability. Interesting idea in the satalite trackers conversion. I have small fabrication shop in the Meadows. Maybe we could get together @ A.E. one day and "chat". Let me know. Later On! Solarmon [img]images/smiles/icon_wink.gif[/img]
Chris Soler

powering trackers

Post by Chris Soler »

I'm using a sattelite dish mount to track my panels. I got a circuit from redrok.com that I stuck in a plastic jar to control the motor. It uses two green led's as the sensors and surface mount components and 4 fets. It's only $36, I've given up designing my own circuit after finding this one. I had to tape a cone of tape around the led's to make it less sensitive (it kept going back and forth due to my less than rock solid mount). It still moves to find the brightest spot in the sky in overcast conditions. It moves back to the east at dark. One thing I had to do was get an actuator with a limit switch to shut it off at the ends, because the circuit stays on all night. So it's not a perfect solution but it worked all winter for me. I used the wire that came with the sattelite dish to bring 12 volt power from the batteries (my panels are at 24 volt). The controller runs on 12 volt and runs the motor 1/10th of the time so the motor moves very slowly, more than a minute to return to the east. The motor is built as a 36 volt unit so it has a low amperage draw (3-4 amps) so the wire can be pretty small. I don't think I'd want to try to run it through the charge controller, especially at night.
Chris
boB

powering trackers

Post by boB »

In talking to Chris on the speakerphone just a few minutes ago, something occured to me... But just now I realize that what could happen is very dependant on when the tracker motor is connected across the panel + and - leads. If it is connected all of the time, then in the very early morning or late evening when there is light but no current available, the motor will load down the panel voltage. So next morning would be when the tracker would reset to the east. If it was a 24V battery system then the tracker motor would drag the panel voltage down to near or below the battery voltage and the MX60 would not wake up. But that should be enough voltage to drive the actuator back to the east in the morning. Just slowly. Then, when there is more light, the MX60 would wake up and operate.
Something else though... When the MX60 wakes up and closes it's internal relays, the MX60 matches the voltage at the PV terminals with the same voltage it was seeing the panel provide before it closed those relays. The MX60 might try to power the motor but if more than a 1/4 amp or so goes TO the actuator, the MX60 will see reverse current and shut off and then wake up again. It will say "Re-Cal" when it does this. This ~might~ be a problem but maybe not. As soon as the sun is really "up", things should be fine I would think. I think the situation would depend on how the actuator motor is controlled.
If anyone plays with this and an MX60, please share with us. I'm curious. [img]images/smiles/icon_rolleyes.gif[/img]
I am just not sure what would happen exactly. I DO know that people use trackers with the MX60 and they work OK as far as I've heard. I'm just not sure about homemade trackers with varying control schemes.
Thanks,
boB Gudgel
rid

powering trackers

Post by rid »

Chris,

I would like to see that tracker, can you please post the URL.

ooops, It's not the same to redrok.com to www.redrok.com. It should be www.redrok.com

I'm thinking about that myself but I was thinking on using my old laptop Pentium 120 Mhz to do that Sun tracking using the parallel port and collect data from the MX60 and transfering it my FTP site.

<small>[ May 12, 2003, 10:03 PM: Message edited by: RID Wireless ]</small>
rid

powering trackers

Post by rid »

Heck!,you are right about that, for $35.00 I'll order the redrok traker.
Fritz
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powering trackers

Post by Fritz »

Today I installed one of the redrok LED tracker controllers on one of my arrays.
(I put off my previous scheme to the point of abandon, went for the simple solution)
Works fine, albeit a bit hyper... needs some tuning / dampening I suppose.
It is a cloudy day and the MX60 is cycling alot, sleeping, wakeup, MPPT, Re-cal, sleeping in about 2 minute intervals
I will have to investigate if this has to do with the tracker cycling or if it is just clouds scudding by.
Then, in the evening I will see what happens when the tracker puts the panels all the way east.
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Re: powering trackers

Post by Harriett »

solarmon wrote: Fri May 02, 2003 10:21 pm Hey Fritz! This MX contoler solves one big problem for me in it's voltage drop capability. Interesting idea in the satalite trackers conversion. I have small fabrication shop in the Meadows. Maybe we could get together @ A.E. one day and "chat". Let me know. Later On! Solarmon Image
One thing I had to do was get an actuator with a limit switch to shut it off at the ends, because the circuit stays on all night. So it's not a perfect solution but it worked all winter for me. I used the wire that came with the sattelite dish to bring 12 volt power from the batteries
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Re: powering trackers

Post by Mike Curran »

@Harriett - You know you're responding to a 17 year old thread, right?
https://smart.tigoenergy.com/p/pZXn7SZQyO45?date=2021-04-19
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
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Re: powering trackers

Post by JRHill »

Mike Curran wrote: Tue Dec 08, 2020 12:32 pm @Harriett - You know you're responding to a 17 year old thread, right?
Some problems just keep going on and on. It might still be relevant Mike!
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Re: powering trackers

Post by sodamo »

We were soooo much younger then 😁
David
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