Author Topic: Paralleling solar panels  (Read 865 times)

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Offline uer166Topic starter

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Paralleling solar panels
« on: May 17, 2023, 06:44:30 am »
I know better not to do it, but I have 10 panels with Vout of 65V each. If i have one string, that is 650V, if two, then 325V. In either case, the price of a total of ~3kW of MPPT capacity is very high for whatever reason. The cheap MPPTs seem to top out at ~250V PV.


So, what are the downsides of paralleling say 5 (or 10) 325W panels, all in identical conditions/temperature, and no shading?
 

Offline Jeroen3

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Re: Paralleling solar panels
« Reply #1 on: May 17, 2023, 07:20:16 am »
The input current of an MPPT is also limited. Typically around 15A.
Paralleling solar panels requires different strategies for power tracking and is uncommon.

I can buy a 3kw growatt with 360 Vdc nom input for less than 500 euro.
Three phase output inverters can typically handle higher dc inputs.
 

Offline uer166Topic starter

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Re: Paralleling solar panels
« Reply #2 on: May 17, 2023, 07:41:08 am »
The input current of an MPPT is also limited. Typically around 15A.

In a non-isolated buck, the input current handling should be same as output, would it not be? All the ones I'm looking at are 40-60A output non-isolated buck MPPTs. 500 Euro is eye-watering for this application. You're right about the panels, it's a totally different optimization..
 

Offline Jeroen3

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Re: Paralleling solar panels
« Reply #3 on: May 17, 2023, 07:57:13 am »
You are looking for a DC/DC application?
 

Online tautech

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Re: Paralleling solar panels
« Reply #4 on: May 17, 2023, 08:23:18 am »
The input current of an MPPT is also limited. Typically around 15A.
Yet the Morningstar ones I remotely monitor are rated to 60A. Commonly see them from 2 and 3 panel arrays charging at 25A.
While double checking that online I notice they have a new 600V product also rated to 60A.
https://www.morningstarcorp.com/products/tristar-mppt-600v/
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Offline uer166Topic starter

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Re: Paralleling solar panels
« Reply #5 on: May 17, 2023, 08:33:31 am »
I should have been more clear, it is a lithium battery application (12s Li-Ion battery) charging.
 

Offline Siwastaja

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Re: Paralleling solar panels
« Reply #6 on: May 19, 2023, 01:02:46 pm »
Is it not an option to buy two of the cheap controllers, paralleling their outputs at the battery instead? That would work the best. If this is too costly, you would save even more if you just did not buy (or sold if you already have them) half of the panels, making a smaller system. The problem with paralleled one is it gives less bang for a buck as it's likely working suboptimally all the time. Of course you get more energy than from a half-sized system, but probably not even near the double, but the panels, their mounting and the location still has cost.
 

Offline uer166Topic starter

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Re: Paralleling solar panels
« Reply #7 on: May 19, 2023, 03:04:00 pm »
That's exactly what I went for, with a bonus that it adds quite a bit of redundancy. I had to get four (4)! units where each can handle only 2-3 panels.

Each being 40A is over-provisioned by about 4x, but that's still way cheaper than a single HV string MPPT.
 


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