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Old 06-10-2016, 15:31   #16
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Re: Charge controller for each solar panel?

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Originally Posted by a64pilot View Post
If you wire in parallel and only have one MPPT, then shading will effect you no more or less than it will if you have an MPPT for each panel, I don't think.
Wiring in series is where it hurts.


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I think you will lose less power from shaded parallel panels than from series, but I think you could lose even less with a controller per panel.

Here's the thinking. We've already seen the drastic losses of series panels when shaded. We've also seen how the voltage drops drastically on a panel when it's shaded only a little. So let's say you have 2 panels cooking along in parallel and they're both putting out 38v and 90% of rated power. The single controller has no problem determining that 38v is MPP and holds it there.

Now the boom comes along and drops the output of the first panel to 20% and voltage from that panel drops to 22v. The second panel is still unshaded and is trying to produce power at 38v. Now we have two different power points - one at 22v, the other at 38v. Which one is the MPPT controller going to ty to maintain, or is it going to split the difference and go for 30v? If so, it's not optimal for either panel.

A system with a separate MPPT controller per panel would suffer the absolute minimal losses from shading, since no matter which panel, or how much it gets shaded, each panel is still going to get tracked at it's max. power point.
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Old 06-10-2016, 15:43   #17
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Re: Charge controller for each solar panel?

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Holly thread hi-jack!

The purpose of this thread is to determine if its worth having a single mppt controller for every panel vs having a single large mppt controller for all panels.

The issue I am having is that I cannot monitor all 5 controllers, I can only monitor one. So I give up monitoring for the extra efficiency.
You could connect all 5 controllers to a bus bar, then connect an ammeter with a shunt to the bus bar and it will show you combined output of all 5 controllers. There are nice V and A meters with 0-30v and 0-100A displays with shunt for about $15 on Ebay.

The controllers I use display input W, output A and V, even though they are inexpensive.

A better known (higher quality) brand is Victron, you can get them in a wide variety of sizes (10, 15, 30, 35, 50, 70, 75, 85, 100A) and 70v, 100v and 150v input, and they communicate to the whole Victron system, for very comprehensive data on your entire electrical system.
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Old 06-10-2016, 16:06   #18
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Re: Charge controller for each solar panel?

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Originally Posted by socaldmax View Post
You could connect all 5 controllers to a bus bar, then connect an ammeter with a shunt to the bus bar and it will show you combined output of all 5 controllers. There are nice V and A meters with 0-30v and 0-100A displays with shunt for about $15 on Ebay.

The controllers I use display input W, output A and V, even though they are inexpensive.

A better known (higher quality) brand is Victron, you can get them in a wide variety of sizes (10, 15, 30, 35, 50, 70, 75, 85, 100A) and 70v, 100v and 150v input, and they communicate to the whole Victron system, for very comprehensive data on your entire electrical system.
Can you post or PM me the brand you use, or some units (inexpensive) you recomend.
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Old 06-10-2016, 16:30   #19
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Re: Charge controller for each solar panel?

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Originally Posted by socaldmax View Post
You could connect all 5 controllers to a bus bar, then connect an ammeter with a shunt to the bus bar and it will show you combined output of all 5 controllers.

A better known (higher quality) brand is Victron, you can get them in a wide variety of sizes (10, 15, 30, 35, 50, 70, 75, 85, 100A) and 70v, 100v and 150v input, and they communicate to the whole Victron system, for very comprehensive data on your entire electrical system.
That's great but I need to figure out how to connect them all to a Victron display. I need a solution that in integrated into the Victron ecosystem.

I am ordering 5 of the Victron 75/15 MPPT controllers.
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Old 06-10-2016, 16:53   #20
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Re: Charge controller for each solar panel?

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Can you post or PM me the brand you use, or some units (inexpensive) you recomend.
I'd recommend the Victron units, very inexpensive for the performance and quality.
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Old 06-10-2016, 16:57   #21
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Re: Charge controller for each solar panel?

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Originally Posted by socaldmax View Post
I think you will lose less power from shaded parallel panels than from series, but I think you could lose even less with a controller per panel.



Here's the thinking. We've already seen the drastic losses of series panels when shaded. We've also seen how the voltage drops drastically on a panel when it's shaded only a little. So let's say you have 2 panels cooking along in parallel and they're both putting out 38v and 90% of rated power. The single controller has no problem determining that 38v is MPP and holds it there.



Now the boom comes along and drops the output of the first panel to 20% and voltage from that panel drops to 22v. The second panel is still unshaded and is trying to produce power at 38v. Now we have two different power points - one at 22v, the other at 38v. Which one is the MPPT controller going to ty to maintain, or is it going to split the difference and go for 30v? If so, it's not optimal for either panel.



A system with a separate MPPT controller per panel would suffer the absolute minimal losses from shading, since no matter which panel, or how much it gets shaded, each panel is still going to get tracked at it's max. power point.


You won't have multiple power points, you will have only one, whether you have 2 or ten panels when you connect them to a single bus bar they in effect become one big panel.

I believe your answer you wanted was given to you, combine all MPPTs to one bus and read the one bus, it's the same as connecting them all to the bank



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Old 06-10-2016, 17:17   #22
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Re: Charge controller for each solar panel?

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Originally Posted by a64pilot View Post
You won't have multiple power points, you will have only one, whether you have 2 or ten panels when you connect them to a single bus bar they in effect become one big panel.

I believe your answer you wanted was given to you, combine all MPPTs to one bus and read the one bus, it's the same as connecting them all to the bank
Not quite...

Having all 5 controllers connected to a bus would only give me the total coming in. I am looking for cumulative data.

Having all 5 MPPT controllers connected corrrectly to the Victron display will tell me the present amperage and voltage is for each MPPT controller, plus how many amp-hours were accumulated for each of the past 30 days, how much time on absorption vs. float, maximum output for the day, etc.
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Old 07-10-2016, 04:31   #23
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Re: Charge controller for each solar panel?

Our boat was set up with one controller per solar panel when we bought it.
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Old 07-10-2016, 04:48   #24
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Re: Charge controller for each solar panel?

(Answering the question about the circled elements in the picture of my MPPT board on the previous page)

Those are indeed simple shunts, I use the 6 individual outputs going to an Arduino programmed system to measure the actual power output of my solar panels and to keep track of them over time, but that's another project.
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Old 07-10-2016, 06:14   #25
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Re: Charge controller for each solar panel?

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Not quite...

Having all 5 controllers connected to a bus would only give me the total coming in. I am looking for cumulative data.

Having all 5 MPPT controllers connected corrrectly to the Victron display will tell me the present amperage and voltage is for each MPPT controller, plus how many amp-hours were accumulated for each of the past 30 days, how much time on absorption vs. float, maximum output for the day, etc.
For cumulative data you would get that by taking readings off the bus. I think you're looking for discrete data ( what each controller is doing) the easest way I can think to do that is to use the Tracer BN series that can connect to a USB port along with their software that lets you monitor what each controller is doing and adjust each one independently. They're not as high quality as the Victron, but are much more user friendly to deal with.
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Old 07-10-2016, 06:43   #26
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Re: Charge controller for each solar panel?

I agree with Pilot. It doesn't matter how many panels you have leading to your controller. They act as one big panel and the controller knows no different. Therefore there is no need to have more than one controller as long as it is sufficiently sized...with the following caveat;

However, if any part of that panel(s) is prone to getting shaded independently of the rest, then it will affect the entire array. If this happens, it is better to separate them. My setup is that I have two sets of panels, one on my hard-top, another on my davits. The panels on the davits are usually all in the sun or all shaded. Therefore, the davit panels have one controller separate to the others.
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Old 07-10-2016, 09:56   #27
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Re: Charge controller for each solar panel?

every body talks 'bout the power going into the controller and all the mathematical theory. but no one talks about the other side. the level of charge of a battery is tested by the controller and the output is adjusted to compensate. Hence if both controllers are hooked to the same bank they will get an erroneous state of charge reading cause by the other controller output, which could only be eliminated by a battery separator. I've had multiple controllers and now use a single. the only "real world" difference I can see is the extra add cost of materials and maintenance. the only thing that makes a decision on what is working is "do I have enough electricity to operate my stuff without running a engine?" I prefer to keep the cost down.
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Old 07-10-2016, 10:14   #28
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Re: Charge controller for each solar panel?

I didn't read all the posts, so forgive me if I'm repeating. You cannot combine dissimilar panels before the controller without significant loss. If the panels are identical, then you can combine (parallel or series) before the controller and use 1 controller. That's what I did when I installed two 275W panels and used the 100v/50A victron bluesolar controller. I currently have series connection b/c i don't really get shade on my arch, but parallel is better if one panel gets shade. I don't think having separate controllers will do much for you in shade vs parallel connection, but may have marginal increase. Of course 2 gives you some redundancy if one fails... not sure the cost trade off is worth it?
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Old 07-10-2016, 10:16   #29
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Re: Charge controller for each solar panel?

Epic,

I have 4 rigid ultra solara panels, each with its own victron mppt controller. All 4 outputs from the mppts go to a bus bar, then through a watts up digital read out, then a fuse then batteries.

My panels are 110watts, and they lie flat on the bimini and dodger, this summer in the med i maxed out at 32amps one day, which i was happy with, so i agree that a controller per panel is the way to go.

Regards the color gx, it is my understanding from reading posts by the victron tech ream on their website that you can indeed connect all 4 or 5 panels to the controller, but they need to be ganged on a usb multi socket then 1 connection to the gx, which then only shows the total watts etc, not the individual panels.

To get individual info i use a lead from each controller to my pc and this gives all the info you require, you can use a bluetooth connector too.

If you have info otherwise, i would be very interested to hear as i am considering a color gx!
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Old 07-10-2016, 10:33   #30
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Re: Charge controller for each solar panel?

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For cumulative data you would get that by taking readings off the bus. I think you're looking for discrete data ( what each controller is doing) the easest way I can think to do that is to use the Tracer BN series that can connect to a USB port along with their software that lets you monitor what each controller is doing and adjust each one independently. They're not as high quality as the Victron, but are much more user friendly to deal with.
I bought one Tracer controller, and I strongly recommend not buying them.

Their MPPT algorithm is lousy, even if the solar input is steady, the controller drifts up and down the voltage range, losing power all the while it's off from MPP. It's by far the worst performing MPPT controller I've seen.
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