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johannes123 avatar image
johannes123 asked

With MPPT RS 450/200-Tr 450V 10A or 225V 20A (2 panels parallel) ´more efficiency?

Hello,

may I ask the following question about the MPPT RS 450/200-Tr:

Would it be general more efficient to use 450V 10A or 225V 20A (string with 2 panels parallel)?

I assume that with 450V also at low light the MPPT will work better?
Or is it not relevant?

On the other hand it might have less loss when transferring down from only 225V instead of 450V to the needed ~ 58V?


And 2nd question:
If all panels receive 100% same amount of light, no shadows, all 100% the same, would it make a efficiency difference whether the panels use 450V 20A (string with 2 panels parallel) on 2 trackers or 450V 10A on 4 trackers?

Thank you very much

Best regards

Johannes

MPPT ControllersMPPT SmartSolar
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jeanmarie avatar image
jeanmarie answered ·

much better to use high voltage than high current, definitively !

20A : a MPPT for RS450 can handle up to 18A, not 20 ! and having panels with Isc <10A is not anymore common those days

But be carreful as 450V is a "false" limit : High voltage is limited to installed batteries. With Pylontech (15S) for instance you must ensure to keep Voc below 414V even by low temperature. Using a 16S battery allows you to go a bit higher (around 440V)

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johannes123 avatar image
johannes123 answered ·

Hello,

thank you very much for your fast answer.

Having a "standard" 430wP 10A panel at Azimut: -41° and tilted 38° at 51.000 latitude it might never reach the full 10A power, so 2 parallel still might be fine?
As the MPPT will cut off / waste the power over 18A, or will it get destroyed?

Yes, I am aware of the max. 450 Volt limit and with the factor down to the battery size that I have some luck with as it should be Pytes E-BOX-48100R-C.

But this factor is - according to the manual - a "should" and not a "must"?
What happens if the converter Voltage of 450 Volt is higher than the factor of battery (as with 15S 414V in your sample??

Best regards

Johannes

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Michelle Konzack avatar image
Michelle Konzack answered ·

The voltage of the Solarpanels can not be bigger then 8 times the maximum Voltage of your batteries otherwise you coock the Buck-Inverter which is not made for a higher ratio

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Michelle Konzack avatar image
Michelle Konzack answered ·

Oh, the 414V mentioned are the Voc and not Vmpp, because if your panels have a temperatur coefficient of -0,4%/°K then at -20°C you would reach 480V and your RS 450/200 is done.

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johannes123 avatar image
johannes123 answered ·

-0,4%/°K then at -20°C

But to make sure the low temperature Voltage does not damage the system can be easily checked in the Victron MPPT calcualtor, right?

While I wonder why it is set to only -10°C, while the company is Netherlands - but also Netherldands can have lower temperatures (I just checked lowest temperature ever 2012 -19,5 °C in Groningen)

So always use the real absolute minimum temperature that can occure at the position of the panels?
So having also about -21°C in my region according to the whether charts as minimum possible.

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Michelle Konzack avatar image Michelle Konzack commented ·

Lucky you!

In Estonia we get nearly every winter over 1-2 days up to -42°C where I live (20km from Rakvere direction Narva) hence my Voc can NOT EXCEED 213V on my SmartSolar MPPT 250/100 VE.Can


With my 410Wp Winaico modules and 6 in series I would hit the SmartSolar hardlimit at +3°C.

With 5 Modules I can go down to -50°C which would be a real ICEAGE!


Oh, I made a mistake in calculation by buing 6 of them and bought recently 4 more to get two sets where the 2nd set is 100% winter optimised and very easy to clean from snow.

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johannes123 avatar image
johannes123 answered ·

Can someone kindly check my calculation of 4strings with each 435Wp?
https://mppt.victronenergy.com#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
https://www.tepto.de/media/e3/94/61/1693381561/230216_2_Datasheet_VertexS+_NEG9R.28_DE_2023_A.pdf

I wonder because the PV max. voltage @ min. Temperature (-20°C) is 459,2 Volts - so higher than the always told max. 450 Volts. But the calculater does still suggest the MPPT RS 450/200-Tr

I used 57,6 volts for battery of Pytes E-BOX-48100R-C, this is right?

Is there a big loss at Azimut: -41° and tilted 38° at 51.000 latitude in summer?
(while I mainly need the MPPT to charge the battery always in the morning and in summer there is already much more AC solar power, but sure if loosing too much power then it might be better to take a RS450/100 or smaller one additional?
Or is the loss of power too low for adding more MPPTS, Cables and Connections?

So I would have gotten mydream configuation, because I need 32 panels.

Again: Thank you very much!

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Michelle Konzack avatar image Michelle Konzack commented ·
Are you sure, you want to calculate with only -20°C and a temperatur coefficient of -0,24%/°K?


2°C lesser and the calculater has no solution for you anymore.


Also chanfing the temperatur coefficient to -0,26%/°K let your RS450/200 disappear.


I had already in North of München (Freiman) 11 years ago already -25°C.


I would not take this risk to loose an MPPT for more the 2000€ especially if we get so much differences of climat every year. I München we got a bitter cold winter and bright sun shine!


Maybe you should think about and make 4 strings 7 modules and one with 4 modules using a smaler SmartSolar MPPT 250/60


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jeanmarie avatar image jeanmarie commented ·

I agree with Michelle.

1) your panels, with an Isc of 10,49 cannot be parallelized, out of warranty for a RS450/200

2) 57,6 is not a consistent floating voltage, it is more usually a shutdown voltage for any BMS with a 16S LFP battery. 56.0V is more consistent as floating voltage (corresponding to 3,5V / cell) and in such case the calculator doesn't suggest any converter


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johannes123 avatar image
johannes123 answered ·

I found a great solution as I think:


As I see other modules have much less voltage but some more ampere, like this 440wP module
JinKo Solar 440W JKM440N-54HL4R-V PV Modul Tiger Neo N-Typ Black Frame
https://cdn02.plentymarkets.com/kmyhaikn11xq/frontend/actec-shop/downloads/Jinko-Solar-Tiger-Neo-N-Typ-54HL4-V-440-W-Black-Frame-Datenblatt.pdf
where I can put even 10 pcs in line and have 1 free MPPT tracker:
https://mppt.victronenergy.com#djM7ZXlKdVlXMWxJam9pTlRBeE9ERWdRbVZrWW5WeVp5d2dSR1YxZEhOamFHeGhibVFpTENKc1lYUWlPalV3TGprNE9UTTBPQ3dpYkc1bklqbzJMalUzTVRFMU1qUjk7ZXlKbVpXRjBkWEpsY3lJNld5SjJhV04wY205dVEyOXVibVZqZENKZExDSjBaWEp0YVc1aGJDSTZkSEoxWlN3aVlXeHNiM2RQZG1WeWMybDZaV1FpT25SeWRXVjk7Y3VzdG9tLDEwLDEsNTcuNiwtMjAsNzAsNDgsMTMuNDEsMC4wNDUsMTMuODYsNDQwLDMyLjgxLC0wLjI5LDM5LjM4LDUwLDY=


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johannes123 avatar image johannes123 commented ·

@jeanmarie

@Michelle Konzack

Do you agree with my idea to use solarpanels with less voltage but more ampere to reach the maximum quantity of solarpanels per MPPT?

Does the RS450/200 "collect the power" from all 4 MPPTs together, or is it a 2x 450/100 system?
I ask to know whether it is important to sort the MPPT strings from different house sides.
For example 2x MPPT string west and 2x MPPT string east, all same quantity and modules.
Does it matter where to put in so for example best to do the following:
1. MPPT string: West
2. MPPT string: East
3. MPPT string: West
4. MPPT string: East
Or does the position of each string not make a difference?

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jeanmarie avatar image jeanmarie johannes123 commented ·
Hi @Johannes123

yes you are right to consider using 54 cells panels instead of the more "classic" 60, 66 or 72 panels, it will help to increase the current, lower the voltage and allowing you to reach the 10 panels in series keeping the voltage to an acceptable level for the RS450 inputs in relation ship with battery voltage.

This RS450/200 is constituted of 4 MPPT, meaning you can have 4 totally independent solar panels groups with each of them it's own orientation and inclination.

The only limit you will face are

- the max capable current the RS450 can inject on the DC bus : 200A, meaning installing more than 11 kWc of panels will cause some saturation and lost in the max production.

- the max power each MPPT can handle according the technical description from Vicrron.


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