Would two charge controllers work well together in the same system

[coultergeist]

Hi,

I'd appreciate some opinions on this. I just finished installing two 158w panels on my van. I am using a 30 amp mppt charge controller. I have room for two more of these panels. That would give me a potential max of around 600 watts. That is too much for the one charge controller to handle. I can get another similar charge controller for about $50. A 60 amp mppt controller is $200 or more. If two charge controllers will work well in the same system, I can simply hook up the second set of panels to the second controller and save a good bit of funds. Is this workable or do I need to suck it up and plan to spend a bundle on the bigger charge controller?

If I'm missing something and there's other options or things I'm not thinking of, please let me know.

Thanks,

Patrick

 

[Optimistic Paranoid]

I'm not an expert, but I thought all charge controllers worked by sensing the voltage on the battery? If, instead of seeing the 12 volts it's expecting to see, it sees the 13 to 14 volts the FIRST charge controller is dumping into the circuit, wouldn't that tell the second controller not to charge the battery?

Regards
John

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On further reflection, how many house batteries do you have? If two, then maybe you could split the system and run a separate charge controller to each? And use one of those marine battery switches to switch between them and or combine them as necessary?

Regards
John

 

[flying kurbmaster]

I read somewhere, that some charge controllers can be linked and used like you intend, but not sure if that goes for all of them.

 

[coultergeist]

Thanks for the responses.

My battery bank is three batteries with a switched connection to the starting battery as well. I might be able to get away with attaching different chargers to different ends of the battery bank, but I think with the amount of solar power I intend to have, I still think that the separate chargers will end up reading each other and going to float mode too soon.

Kurbmaster, I researched about solar chargers that can be connected together. It is called paralleling. That would be possible with some controllers. Alas, the one I have now does not have that capability.

I have looked a good bit and I think the only real choice is to upgrade to a single larger unit. I am looking at getting a 60 amp charge controller. I am going to get one that can be paralleled so that if I expand further in the future, I won't have to replace the charge controller again.

Patrick

 

[flying kurbmaster]

are you planning on running a washer and dryer in that van???? are you converting to electric motor, that would be cool.

 

[Zil]

Can the 30a mppt handle more voltage if you series the panels?

 

[coultergeist]

Hi kurbmaster, no washer and dryer in here. Converting to electric drive motors would be pretty cool, but that is well beyond my mechanical skills. I have noted that with all the rain and cloudy days we've had since the panels got installed that they are just barely keeping up with the fridge and my pretty minimal power draw. I was going to add more panels in the future as extra insurance for future increased power use. I have enough funds saved up now, so I figure it's better to go ahead and have it all done now. Of course I do tend to err on the side of overkill

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Hi Zil, that actually is something I looked at. I could series the panels and they would just fit inside the 30 amp rating with a little room to spare. The problem is on the battery side. My battery bank and inverter are set up for 12volts. The output to the battery bank side would be well in excess of 50 amps at 12volts at full solar production. That would far exceed the controllers rating.

I could convert over to a 24volt battery bank setup. That would allow me to keep the charge controller I have now as the output to the battery bank would then be around 25 amps. The problem is that I would need to replace my big inverter with a 24volt unit and do a bunch of rewiring I'd really rather not do. It was a great suggestion though.

Patrick

 

[WheelEstate USA]

If you live where there's lots of clouds and rainy weather a small genny might be a good investment.
You can add more panel, but without the sun you're still not producing.