Direct parallel connection of 2 EAST and WEST PV solar strings with (very) different panels and voltages?

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izentrop
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Re: Direct parallel connection of 2 EAST and WEST PV solar strings with (very) different panels and voltages




by izentrop » 24/11/21, 11:23

Christophe wrote:2 diodes and 2 fuses is always cheaper than a new inverter!

Then you have to choose them well and make a clean installation if you want to be quiet for years !!
It must protect against reverse voltages and waste the least energy while costing as little as possible.
If your PV can deliver 300 W / 300V therefore 10 A, a diode of this type https://docs.rs-online.com/97f2/0900766b814d6c95.pdf dissipate about 11 W, you will need a radiator to dissipate the heat.
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Re: Direct parallel connection of 2 EAST and WEST PV solar strings with (very) different panels and voltages




by Christophe » 24/11/21, 11:26

You bugger Izy! That would be 1A ... : Mrgreen:

Generally solar thongs work between 5 and 10A ... but yes for the radiator, no worries with that!
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izentrop
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Re: Direct parallel connection of 2 EAST and WEST PV solar strings with (very) different panels and voltages




by izentrop » 24/11/21, 11:32

Ha yes you're right, but why were you talking about 300V?
Should the characteristics of the "string"
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Re: Direct parallel connection of 2 EAST and WEST PV solar strings with (very) different panels and voltages




by Christophe » 24/11/21, 12:16

Because generally a string at an individual works between 250 and 350 V (6 to 10 panels in series, it depends on the panels obviously ...)

In high limit, my inverter accepts up to 600V (some are at 1000V or about twenty panels in series is rare among individuals ...).

And it starts to inject at approximately 110-120V (the lower the better, otherwise it is 100% lost start and stop production ...)
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izentrop
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Re: Direct parallel connection of 2 EAST and WEST PV solar strings with (very) different panels and voltages




by izentrop » 24/11/21, 13:34

Ah ok, so https://fr.aliexpress.com/item/1005003186131987.html 45A 600V is largely sufficient as a non-return diode to couple 2 "strings" of 350 V 10 A, but they must be paired.
They will work much better if they are both facing south.

Total back-to-back panels probably have a special design to be able to produce out of favored direction? https://www.entraid.com/articles/clotur ... -verticaux
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izentrop
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Re: Direct parallel connection of 2 EAST and WEST PV solar strings with (very) different panels and voltages




by izentrop » 24/11/21, 17:56

By searching a little, the panels of total are constructed by https://www.next2sun.de/referenzen/
We see that they use N-pert cells
Which leads to a Chinese manufacturer https://www.dsnsolar.com/solar-cells/n- ... -cell.html

A study http://e-biblio.univ-mosta.dz/handle/12 ... ?show=full
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Christophe
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Re: Direct parallel connection of 2 EAST and WEST PV solar strings with (very) different panels and voltages




by Christophe » 24/11/21, 18:01

izentrop wrote:Ah ok, so https://fr.aliexpress.com/item/1005003186131987.html 45A 600V is largely sufficient as a non-return diode to couple 2 "strings" of 350 V 10 A, but they must be paired.


Ah yes it looks good this one ... on paper!

What do you mean by paired?

izentrop wrote:They will work much better if they are both facing south.


Yes of course but that is NOT the subject of this topic!

izentrop wrote:Total back-to-back panels probably have a special design to be able to produce out of favored direction? https://www.entraid.com/articles/clotur ... -verticaux


Same, not the subject ...
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izentrop
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Re: Direct parallel connection of 2 EAST and WEST PV solar strings with (very) different panels and voltages




by izentrop » 24/11/21, 18:43

Christophe wrote:What do you mean by paired?
I talked about it, it's to limit mismatch losses https://ateliersolaire.ch/le-mismatch/
https://www.photovoltaique.info/fr/real ... rformante/
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Re: Direct parallel connection of 2 EAST and WEST PV solar strings with (very) different panels and voltages




by Christophe » 24/11/21, 18:47

Well, no one does that except maybe for parks with several thousand signs!

When you buy X solar panels you are not going to sort them to throw away X%! No private individual does this ... even at 1 € per Wc! : Shock: : Shock: : Shock:

Pairing of modules

The modules naturally have different characteristics (even very few) that can create imbalances during their association within a photovoltaic field. This difference in performance between modules of a branch or between branches placed in parallel is called the "mismatch". These imbalances degrade the MPP (maximum performance point) of the series of modules and lead to a drop in usable energy. In order to limit this phenomenon, the associated modules will be sorted in order to have the most homogeneous possible currents. Depending on the power tolerance, this practice may reduce mismatch losses from 1,5% to 0,4% for a dispersion of 10%. In practice, the modules are sorted according to their MPP current as soon as the individual power tolerance of the modules exceeds 8%. This sorting is carried out on the basis of the characteristics measured when leaving the factory by the manufacturers (flash test).


Logically, a good manufacturer does this before putting his panels on the market ...

The rest is commercial bullshit to sell micro inverters I think ...
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Re: Direct parallel connection of 2 EAST and WEST PV solar strings with (very) different panels and voltages




by GuyGadeboisTheBack » 24/11/21, 19:07

(After the heated pool, Christophe puts on two heated thongs: one upside down, the other upside down ... I don't understand anything anymore !!!) : Mrgreen: : Oops:
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