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Post Info TOPIC: MPPT solar controllers in parallel
Whenarewethere


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MPPT solar controllers in parallel
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Since I have 2 Victron MPPT controllers & 6 solar panels set up as 2 panels in series then in 3 sets. 

 

I connected 4 x 26AH & 80AH & 85AH batteries together. 

 

Both controllers I tested separately with 120watts of panels. In summer I can easily get 125watts out of the panels & squeezing them hard (water cooling) up to 137watts! Each controller collected 111watts 26th June in Sydney.

 

So let's say you have a controller & you wanted to add some more panels & the controller doesn't have enough capacity. 

So you use a second controller with the additional solar. In this situation I have 80watts on one controller & 40watts on the second controller.

 

While both controllers are charging in Bulk mode everything works ok. But in this situation the 100/20 controller went to Absorption mode & the amps dropped, while the 75/10 controller stayed in Bulk mode trying to push out as many amps as possible.

 

So while both controllers are in Bulk mode, 2 controllers are not an issue. But, one controller goes into Absorption mode thinking the voltage is high enough. In actual fact the batteries could have still taken the maximum amps available.

 

If you can use one large controller it would be better. If you have to use 2 controllers it is ok but you could be missing out on some input.

 

Victron 100-20 and 75-10 co.jpg

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-- Edited by Whenarewethere on Sunday 27th of June 2021 08:15:35 AM

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Peter_n_Margaret


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Whenarewethere wrote:

 

So while both controllers are in Bulk mode, 2 controllers are not an issue. But, one controller goes into Absorption mode thinking the voltage is high enough. In actual fact the batteries could have still taken the maximum amps available.

 

 

The one that goes into absorption early is not set correctly.

Fix that and the problem goes away.

Each controller is doing exactly what it is set to do.

Cheers,

Peter



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OKA196, 4x4 'C' Class, DIY, self contained motorhome. 960W of solar, 400Ah of AGMs, 310L water, 280L fuel. https://www.oka4wd.com/forum/members-vehicles-public/569-oka196-xt-motorhome
 

 
Jaahn


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Hismile

Interesting information but did show (I think ! ) what we knew. In bulk mode while the voltage is lower than the setting the multi regs will just put the power in OK. MPPT or PWM regs. Possibly depending on the panel differences and the regulator actual voltage accuracy one will get to a mode change first. By then the bulk of the charge is in ! Possibly if the panels are large and the battery absorbtion is slower there may be some up and down at this point, sometimes called fighting each other, but really it is just a machine working to achieve its setting. Nothing to see there really IMHO.hmm

Those tables of information you put up are interesting but even I have trouble making sense out of them and knowing what it presented smile I would not like to think we drive some newbies away. However you did start a new thread !

A comment on setting the regulators. They are not precision voltage devices and the voltage settings are not very accurate often. You could play with them with a multi meter to adjust them closer.  Obviously better quality gear is probably more accurate. 

Jaahn   



-- Edited by Jaahn on Sunday 27th of June 2021 09:28:54 AM

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Whenarewethere


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I looked at all the settings in both controllers, they are set to the same. So any difference is either variation in components or underlying programming. As I don't need a second controller I'm not going to fiddle around adjusting the voltage. Personally I would just buy another larger controller.

Screenshot_20210627-165209~2.png

 

A bit of a circus in the car, Anderson plugs & jumper cables connecting up 269AH of batteries.

7979204947267901067.jpg



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Procrastination, mankind's greatest labour saving device!

50L custom fuel rack 6x20W 100/20mppt 4x26Ah gel 28L super insulated fridge TPMS 3 ARB compressors heatsink fan cooled 4L tank aftercooler Air/water OCD cleaning 4 stage car acoustic insulation.
Peter_n_Margaret


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Multiple controllers are the best solution for failure and the best solution for different panels operating under different conditions.
Multiple small controllers can also be cheaper than a single large one.
Cheers,
Peter

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OKA196, 4x4 'C' Class, DIY, self contained motorhome. 960W of solar, 400Ah of AGMs, 310L water, 280L fuel. https://www.oka4wd.com/forum/members-vehicles-public/569-oka196-xt-motorhome
 

 
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