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Old 09-06-2013, 11:46   #1
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Can I use 12v and 24v panels with same controller?

Hi all,
The sheer tonnage of what I don't know about solar and controllers is staggering. I have been following many of the threads here, and want to know if I can have two large 24v panels on my arch, and two smaller 12v panels on my port and starboard railings? Will one of the fancy controllers be able to work with this?

Cheers, Bill
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Old 09-06-2013, 12:17   #2
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Re: Can I use 12v and 24v panels with same controller?

You can wire the 2 12v panels in series, then parallel that with the 24 v panels.

However MPPT regulators work best when the Vmp of the panels match closely and with different types of panels in very different locations they are unlikely to be close.

You will not damage anything, but the output will be less than optimum.

An alternative using a large MPPT regulator for the two 24v panels and a separate (MPPT or non MPPT) regulator for the 12v panels, or even better a separate MPPT regulator for each of the 12v panels. This option will give you more power, but may not be worth added complexity.

Knowing the specs of the panels, would be a help.
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Old 24-06-2013, 18:16   #3
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Re: Can I use 12v and 24v panels with same controller?

Noelex, thanks for the info. What I am picturing is two large (245w or larger) panels on my arch. Then maybe two smaller panels on my stern lifeline/railing (100w or larger). That is why I was asking about using 24v and 12v panels together. If I could find smaller panels in 24volts, my problem would be solved.

Keep the advice coming please

Cheers, Bill
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Old 25-06-2013, 05:35   #4
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Re: Can I use 12v and 24v panels with same controller?

not sure why you want to fit 24v panels, is the system 24v or 12v? You would be better off with multiple 12v panels connected in parallel to the controller. Depends how much you believe the hype about MPPT controllers as to whether you can justify the high cost for the small gain, cheap MPPT controllers don't even make good paper weights so don't waste your $$ there, a fairly reasonable rule of thumb is if the MPPT controller is less than $500 spend half that and buy a good PWM controller, Plasmatronics in Aust make a good PWM unit, a new 40 amp Dingo has been added to the line up. They have a lot of add on's that can make it a battery monitors as well, a link to the computer is available, they have a long data history storage, completely adjustable, good value for money.
No, I don't sell them or have shares or work there etc, just use quite a bit of their products and they have never let me down.

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Old 25-06-2013, 06:28   #5
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You could use several different controllers one for 24 one 12. I would also concider using several small pannels insted of one large one. If you have any damage you can replace one small pannel insted of one large one. Also if you put a controller on each pannel the others will produce power over the one that is shaded. Just a thought.
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Old 25-06-2013, 06:48   #6
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Re: Can I use 12v and 24v panels with same controller?

Quote:
Originally Posted by montenido View Post
Noelex, thanks for the info. What I am picturing is two large (245w or larger) panels on my arch. Then maybe two smaller panels on my stern lifeline/railing (100w or larger). That is why I was asking about using 24v and 12v panels together. If I could find smaller panels in 24volts, my problem would be solved.

Keep the advice coming please

Cheers, Bill
It is a problem there is no ideal solution.
At 490w for the main two panels you are in the category of the big and expensive MPPT controllers. Its a shame not to use this for the smaller 100w panels, but with panels in different locations with different specs it is sub optimal.

If you can find 2x100w panels with close to 1/2 the Vmp of the 245w panels I would use one big MPPT controller with the 2x100w panels in series and the 2x 245w in parallel
However you may not be able to find panels that are suitable in the correct size for your instalation.
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Old 25-06-2013, 06:51   #7
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Quote:
Originally Posted by T1 Terry View Post
not sure why you want to fit 24v panels, is the system 24v or 12v? You would be better off with multiple 12v panels connected in parallel to the controller. Depends how much you believe the hype about MPPT controllers as to whether you can justify the high cost for the small gain, cheap MPPT controllers don't even make good paper weights so don't waste your $$ there, a fairly reasonable rule of thumb is if the MPPT controller is less than $500 spend half that and buy a good PWM controller, Plasmatronics in Aust make a good PWM unit, a new 40 amp Dingo has been added to the line up. They have a lot of add on's that can make it a battery monitors as well, a link to the computer is available, they have a long data history storage, completely adjustable, good value for money.
No, I don't sell them or have shares or work there etc, just use quite a bit of their products and they have never let me down.

T1 Terry
This isn't good advice Terry , you don't have to spend a fortune to get reasonable mppt, if you know what you are looking at

Dave
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Old 25-06-2013, 07:18   #8
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Re: Can I use 12v and 24v panels with same controller?

More from bad experience than anything Dave, to make an MPPT regulator work well over a wide range, rapid sampling and tuning on the fly rather than shut down and take a reading, then determine a suitable algorithm and go again, and carry a decent current rate costs $$, you can't make a circuit like that cheaply and still make money, none of them are in it as a charity venture, so an MPPT controller that really will work better than a PWM controller is going to cost good $$, it's just the way it is. There are a heap of cheap controllers on the market with the MPPT letter attached, they aren't the real deal, just a waste of money and effort.

T1 Terry
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