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Old 27-02-2019, 14:29   #1
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Different panels, one MPPT controller

I had two identical 50W panels in use in parallel with a PWM controller. I have ordered a Victron SmartSolar MPPT controller with the intention of putting the two panels in series to feed into it. However today I discovered that one of the panels is faulty and that type canít be bought any more, so Iím going to have to have two different panels with one controller.

What aspects of the panels should I try and match when purchasing a replacement?

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Aedan
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Old 27-02-2019, 17:54   #2
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Re: Different panels, one MPPT controller

Best to have all the panels on a given SC match in every way.

But if going to mix, the Voc and Vmp are the critical specs to get exact.

But MPPT is not going to give as much a boost over PWM.

Look at getting two smaller Victrons, usually just as cheap as one big one. Also better shade handling.
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Old 27-02-2019, 22:49   #3
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Re: Different panels, one MPPT controller

Quote:
Originally Posted by john61ct View Post
Best to have all the panels on a given SC match in every way.

But if going to mix, the Voc and Vmp are the critical specs to get exact.

But MPPT is not going to give as much a boost over PWM.

Look at getting two smaller Victrons, usually just as cheap as one big one. Also better shade handling.
If you are putting the panels in *series*, then you should try to match Imp.

I agree that on a boat, due to shading problems you may be better served with individual controllers for each panel.
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Old 02-03-2019, 09:44   #4
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Re: Different panels, one MPPT controller

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If you are putting the panels in *series*, then you should try to match Imp.

I agree that on a boat, due to shading problems you may be better served with individual controllers for each panel.
I have a similar question, but in my case I have a parallel connection of 4 Sunpower E series 327w panels connected to one Outback 80

I want to add a 5th panel of same size (96 cells) over the davits, but Sunpower is no longer available in the Philippines.

Do I still have to match Voc etc exactly as John advised?
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Old 02-03-2019, 12:16   #5
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Re: Different panels, one MPPT controller

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I have a similar question, but in my case I have a parallel connection of 4 Sunpower E series 327w panels connected to one Outback 80

I want to add a 5th panel of same size (96 cells) over the davits, but Sunpower is no longer available in the Philippines.

Do I still have to match Voc etc exactly as John advised?
An *exact* match isn't critical, but a close match is a good idea. Getting a close match at Vmp is what I would be looking for. If the panels have the same number and type of cells per string it's probably going to be close enough.

For a 12V example, my 20-year old Shell Solar 100W panels have two parallel strings of 36 monocrystalline cells, giving a Voc of 21.7V, and a Vmp of 17.5V. A newer Sunpower 100W panel has a Voc = 21.2V, Vmp = 17.7V. These two panels would parallel very nicely.

A Renogy 100W mono panel also has 36 cells in a single string. Voc = 22.5V, Vmp = 18.9V. The Vmp isn't as close, but as best as I can read the panel curves, the power at 17.5V is only down about 4%. I would still use this panel without reservations.
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Old 02-03-2019, 14:13   #6
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Re: Different panels, one MPPT controller

So in my planning, I will have one 160 panel and two 50 watt panels. I was told I could use 1 controller by some for all three...... and some say 1 controller for the 160 then 1 controller for the two 50 watt panels that will be in parallel....... thoughts??

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Old 02-03-2019, 15:01   #7
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Re: Different panels, one MPPT controller

Already been answered.

Ideal is one to one ratio.

Next best is all panels per SC match.

Then come partially matching, dead last is widely different.

To me, it is important to maximize watts output into the bank per square area available.

Others don't care, so can sacrifice lots of efficiency to save some up front money.

Your rig, your choice.
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Old 03-03-2019, 04:55   #8
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Re: Different panels, one MPPT controller

Same here, I have 3x100w now and a 50w panel. Definitely don't want to complicate life with 4 controllers...

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Originally Posted by NYSail View Post
So in my planning, I will have one 160 panel and two 50 watt panels. I was told I could use 1 controller by some for all three...... and some say 1 controller for the 160 then 1 controller for the two 50 watt panels that will be in parallel....... thoughts??

Thanks
Greg
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Old 03-03-2019, 05:42   #9
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Re: Different panels, one MPPT controller

Just 2 would be fine, no one is saying toss out the existing SC with matched panels.

Parallel thread http://www.cruisersforum.com/forums/....php?p=2838352
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