Poor Design? How can I hook up Mixed Panels?

[tbodine88]

This is the schematic of my system. Problem is with only the 200W hooked up and the battery at 12.5 v charge current is 1.4A


With all panels connected & battery voltage at 13.4v 200w panel puts out .7A and the 100W puts out .1A the 15W shows a flashing battery symbol.


Can I correct this? is there a controller that will take multiple solar inputs and combine them so all panels can contribute to charging?

[Statistical]

This is on a boat? It is weird it looks like the panels are wired into AC. That is more typical for grid tie residential setup. Are those modules attached the panels solar optimizers or micro inverters (neither of which are typical for marine setup)?

There likely isn't a good way BUT to know what your options are need to know the voltage of the panels not just their wattage. If the 100W and 200W panels are the same vMPP (voltage at maximum power point) they could be put in parallel at least with a DC MPPT controller. Honestly this entire setup is kinda bizare for a boat.

Usually the standard way of doing things is same panels in parallel or series connected to a DC MPPT (or PWM) controller connected to the battery. If there are differing panels multiple MPPT (or PWM) controllers are used for each group of similar panels.

[wholybee]

It is weird. I don't think the panels are connected to AC, I think there is a relay so that when AC is available the soler is disconnected. Note the relay coil connects to AC, but the contact is connected to battery positive.

What brand of solar controllers are you using? Having a separate controller for each panel is the best way when the panels are very different. However, if you have older or cheap controllers that are just on/off relay type, performance will be very poor like you see. PWM controllers would be a little better, but you really should get some good MPPT controllers in there. Best would be something like Victron where the controllers can talk to each other, and change stages together.

Keep in mind, 13.4V is a fully charged 12V battery. There really shouldn't be very much current at that time. Just a tiny bit of float current.

[noelex 77]

The circuit diagram is confusing , but if I am understanding correctly, you have a seperate controller for each solar panel.

If this is accurate each panel should contribute the optimum output. 0.7A @ 13.4v is only just over 9w so this is very poor for a 200w panel, unless the solar conditions are abysmal.

I suspect something is very wrong with your system.

[Spot]

Hi Tom, what are the two unlabeled items near the ACR and the two colored ones upper right corner of schematic?

If you reduce the system to one solar panel, one controller, one battery-do you get decent readings at the controller and battery?

[wholybee]

Originally Posted by Spot

Hi Tom, what are the two unlabeled items near the ACR and the two colored ones upper right corner of schematic?

If you reduce the system to one solar panel, one controller, one battery-do you get decent readings at the controller and battery?

The two items near the ACR are batteries. The color items are volt meters, one connected to a battery, the other to AC.

[wholybee]

Originally Posted by noelex 77

The circuit diagram is confusing , but if I am understanding correctly, you have a seperate controller for each solar panel.

If this is accurate each panel should contribute the optimum output. 0.7A @ 13.4v is only just over 9w so this is very poor for a 200w panel, unless the solar conditions are abysmal.

I suspect something is very wrong with your system.

I think he just needs better solar charge controllers. We need to know more about what he has there.

The cheapest controllers are just a relay that connects the panels to the battery until the voltage reaches a preset charged level. Weird things might happen if 3 of those are paralleled together, especially with such a huge difference in panel size. The VOC of the 15W panel is much less than the others, that would screw stuff up if it was paralleled directly to the other panels.

Or, if he has slightly better cheap PWM controllers, they might be in float at 13.4V, which would also explain the very low current.

In either case, we need to know what kind of controllers he has. I would recommend upgrading to good MPPT controllers, and unless he has a good reason for it, eliminate the solar cut out relay.

[Spot]

Originally Posted by wholybee

The two items near the ACR are batteries. The color items are volt meters, one connected to a battery, the other to AC.

I am not seeing the AC feed to the meter, it looks like both meters hit the batteries.

[tbodine88]

Originally Posted by wholybee

What brand of solar controllers are you using?

2 each Renogy MPPT on the 200W and 100W

That blue lable chinese MPPT controller you see all over the internet

Originally Posted by wholybee

Having a separate controller for each panel is the best way


Keep in mind, 13.4V is a fully charged 12V battery. There really shouldn't be very much current at that time. Just a tiny bit of float current.

[/QUOTE]
That was what I was trying for, thanks

[Statistical]

Originally Posted by tbodine88

That blue lable chinese MPPT controller you see all over the internet

So if each panels is hooked to their own MPPT then what is all the solar relay cutoff stuff? MPPT should simply stop charging based on the 3 stage programmed charging curve. It is its own cutoff.

As for your poor performance ... buy Chinese garbage get Chinese garbage.

Good MPPT controllers communicate with each other so they can coordinate charging. Ideally they also have a method of detecting battery voltage at the battery. You may be getting very little current because each charger is seeing the other charger output as meaning the batteries are at a high state of charge and so dropping to float.

The other possibility is these aren't MPPT controllers. "Chinese Garbage" (TM) brands tend to lie. I have seen people swearing they have MPPT controller when it turns it is a PWM controller with an MPPT label.

As a test confirm the battery state of charge is reasonably low (<70%). If it is too high run some loads to get it. Then disconnect two of the MPPT so only one is active at a time. Do they work as expected as the only MPPT? If so the problem is likely just buying Chinese garbage and they probably aren't smart enough to work together properly.

[tbodine88]

Voltage ratings
sunny 200W 22.5V
cloudy 100W 18.3
sunny 15W >13v


I selected the panels by where they'd fit. the 15w fits between the cabin hatch and grab rail.
the 100w on the cabin hatch
the 200w on the Bimini


The relay disconnects solar from the charge circuit so the charger sees just the battery voltage, and can act properly

[Statistical]

Originally Posted by tbodine88

Voltage ratings
sunny 200W 22.5V
cloudy 100W 18.3
sunny 15W >13v


I selected the panels by where they'd fit. the 15w fits between the cabin hatch and grab rail.
the 100w on the cabin hatch
the 200w on the Bimini


The relay disconnects solar from the charge circuit so the charger sees just the battery voltage, and can act properly

I would start with testing each controller separately and post the results. If they all work as expected separately and only have poor performance together it is likely just they are poorly coordinated. Chargers can't see SoC directly they determine it by voltage and these don't have any sense leads or any communication with a battery manager so they are measuring the "battery" voltage at the output terminal so they may just not work well in parallel.

For the test be sure your state of charge (double check bat voltage) is low enough to go into bulk. If you have a clamp meter I would check the panel current as well. That will let you determine the power in & out for each panel/controller because the output is going to vary based on the input so seeing the output only is only half the picture.

As for your charger relay you really shouldn't need it but it likely isn't the source of your issues.

[tbodine88]

Thanks

I just experienced a gale. Which blew off the 200w
It's in the cabin now.
I disconnected shore power.
Now the 100w shows .4 amps
The 15w shows it's charging

I am thinking of combining the 100 and 200 into a single circuit

Thanks again for your observations and suggestions.

[Statistical]

As a heads up you may not have MPPT controllers.

This image you posted
https://image3.pushauction.com/3/0/0...75bd10f142.jpg



shows up in a lot of PWM listings. So either someone make a MPPT and PWM model which are absolutely identical or someone lied and sold you a PWM controller as a MPPT controller.

Putting panels in series or parallel can work but with different voltage and amps there will be a lot of losses. In series the voltages are added together but the current is the lowest of all the amps. In parallel the amps are added together but the voltage is pushed down by the lowest voltage panel.

[Spot]

Originally Posted by Statistical

As a heads up you may not have MPPT controllers.

The Amazon vendor I last bought from sells them both ways at 30 amps.
Is there a way to determine if a controller is really one or the other?
Is it still good practice to fuse the charge controller output to battery?