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MASSIVE Overpaneling -MPPT input current

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Zsiger

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Hello guys!

Please help me clear this!
(if it's already discussed, SORRY for repeat)

Some intro:
I have a PowMr 5.5kW off grid SCC+inverter (yea know it's not the top quality stuff on the market). I have 9x385W (3465W) mono panels connected to it. I have a 100Ah 51,2V LifePo4 battery. I'm using it for 2 years now without any problem.
Recently I upgraded the system a little bit: bought a Victron Smartsolar 100/20(48V) SCC with 2*285W poly pv panels and connected them to the battery too.

This whole system is a kinda test, experiment or more to say... hobby for me.

But, the question: what about extreme overpaneling?

If I'm right the SCC only draw that much power from the panels, that it pushing out to the battery.
So (theoretically) If I don't exceed the SCC's max input voltage, and make everything correct (correct connecting, fuses, polarity, etc..) I can connect infinite amount powered solar array?

For exapmle:
Victron 100/20.
Max voltage:100V.
Max current: 20A (max. battery charge 58*20A=1160W).
If I connect a 2s10p solar array (about ~Vmp:75V and Imp:90A =~6750W) there won't be ever any problems. I just waste a lot of power cause of clipping, right?

Is there any chance of the SCC somewhy try to draw more than 20A? Sudden cloud, then back full sunshine or any tracking anomaly? Any danger about it? What about Isc? When will the SCC short circuits the PV input? And why? Because the manual have a max input Isc (20A).

Is anybody here own a system with 400% - 500% overpaneling? What are the experiences?

I know it is a brutal amount of energy waste in summer but now I'm only interested about the physics.


Thanks any answers!
 
Last edited:
I have a 600w array on a Victron mppt 100/30, (clips above 440w), it does work in that range, but it also tends to cause some issues with driving the charging voltage a bit high when clipping a lot - which causes that mppt to hit Absorbing and float - well before the other mppt does.

Because of that I am planning on breaking up that array - back to 420w…

One more array (more solar) because I need the tax credit… or something like that.
 
Zsiger said:
Hello guys!

Please help me clear this!
(if it's already discussed, SORRY for repeat)

Some intro:
I have a PowMr 5.5kW off grid SCC+inverter (yea know it's not the top quality stuff on the market). I have 9x385W (3465W) mono panels connected to it. I have a 100Ah 51,2V LifePo4 battery. I'm using it for 2 years now without any problem.
Recently I upgraded the system a little bit: bought a Victron Smartsolar 100/20(48V) SCC with 2*285W poly pv panels and connected them to the battery too.

This whole system is a kinda test, experiment or more to say... hobby for me.

But, the question: what about extreme overpaneling?

If I'm right the SCC only draw that much power from the panels, that it pushing out to the battery.
So (theoretically) If I don't exceed the SCC's max input voltage, and make everything correct (correct connecting, fuses, polarity, etc..) I can connect infinite amount powered solar array?

For exapmle:
Victron 100/20.
Max voltage:100V.
Max current: 20A (max. battery charge 58*20A=1160W).
If I connect a 2s10p solar array (about ~Vmp:75V and Imp:90A =~6750W) there won't be ever any problems. I just waste a lot of power cause of clipping, right?

Is there any chance of the SCC somewhy try to draw more than 20A? Sudden cloud, then back full sunshine or any tracking anomaly? Any danger about it? What about Isc? When will the SCC short circuits the PV input? And why? Because the manual have a max input Isc (20A).

Is anybody here own a system with 400% - 500% overpaneling? What are the experiences?

I know it is a brutal amount of energy waste in summer but now I'm only interested about the physics.


Thanks any answers!
Click to expand...
Max short circuit current for that 100/20 controller is 20A. I’d stay under that so you don’t risk damage to the controller.
 

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Please STOP IMMEDIATELY ! You are about to burn your system up !
You cannot over panel as you describe - it will fail and terribly so.

When the 100/20 SCC (Solar Controller) @ 48V is limited to
100VDC, 1160W MAX input and 20A.
Exceed the PV Voltage & Max Amps it will fry the fuse hopefully before the SCC. Victron does NOT have HyperVOC capability which does allow for slight over panelling. But it isn't much.

Case Point; My Array is aimed Due South @ 45 Degrees. This provides OPTIMAL generation in March & September for me. In those months my array can over produce by 200-250W & over 25V over SCC limit (when sun is perfectly aligned for about an hour). I use a Midnite SCC which has HyperVOC and can handle it but a Vicky would die. While the rest of the year this is a non-issue.

Where you CAN get away with some over panelling: When you cannot set panels at optimal angles or direction which would result in never seeing Full Capacity coming from the panels you can compensate with over panelling. BUT you must be certain that when the highest production of that array is achieved it does NOT go over the limits.

1714072881188.png




< for 48V system,
<
 
SoakedUp said:
Max short circuit current for that 100/20 controller is 20A
Click to expand...
Yea that's clear.
But when will the SCC reach this status? When will it short circuits the PV input?
Isn't it only about the reverse polarity protection?
 
Steve_S said:
Please STOP IMMEDIATELY ! You are about to burn your system up !
You cannot over panel as you describe - it will fail and terribly so.

When the 100/20 SCC (Solar Controller) @ 48V is limited to
100VDC, 1160W MAX input and 20A.
Exceed the PV Voltage & Max Amps it will fry the fuse hopefully before the SCC. Victron does NOT have HyperVOC capability which does allow for slight over panelling. But it isn't much.

Case Point; My Array is aimed Due South @ 45 Degrees. This provides OPTIMAL generation in March & September for me. In those months my array can over produce by 200-250W & over 25V over SCC limit (when sun is perfectly aligned for about an hour). I use a Midnite SCC which has HyperVOC and can handle it but a Vicky would die. While the rest of the year this is a non-issue.

Where you CAN get away with some over panelling: When you cannot set panels at optimal angles or direction which would result in never seeing Full Capacity coming from the panels you can compensate with over panelling. BUT you must be certain that when the highest production of that array is achieved it does NOT go over the limits.

View attachment 211530




< for 48V system,
<
Click to expand...
Thanks but something isn't clear.
That number is an example.
The essential:
What if I have a huuuge solar array what never exceeds 80V (not Vmp, not Voc), not ever reach the 100V limit.
But the array is capeable of pushing 100A current.
So if I'm righ te SCC only DRAW as much power as it need. Like a 230V AC connector in your wall: if your connect a 100W lamp into it, the grid won't push 300Amps only because it have the POWER.

In short. If I have a 10kW array which never exceed 80V, I set the max OUTPUT current to 19Amp, why and how would demage my SCC?
Why would it DRAW more power than it need?
 
Zsiger said:
Yea that's clear.
But when will the SCC reach this status? When will it short circuits the PV input?
Isn't it only about the reverse polarity protection?
Click to expand...
Ahh I see what youre asking now. The SCC will see a short circuit when the panels short circuit. So technically if there’s never a short circuit I would assume everything would work fine and just clip the excess power above 20A. If you’re worried about damage to the SCC just add a 20A fuse before the controller to ensure you never exceed the limit of the SCC. I’m honestly not sure if the controller will see any damage otherwise, but I’d assume running it at 100% of its capability won’t help it last long.
 
SoakedUp said:
Ahh I see what youre asking now. The SCC will see a short circuit when the panels short circuit. So technically if there’s never a short circuit I would assume everything would work fine and just clip the excess power above 20A. I’m honestly not sure if the controller will see any damage but I’d assume running it at 100% of its capability won’t help it last long.
Click to expand...
I think we are at the point now!
Its not an ,,accident,, I'm asking this.
I built everything very carefully. I have multiple layers of fuses, bigger diameter cables, 3x checking every voltage, polarity, and so on.... I don't want to try anything that can leading to demage.

The thing I'm. really planning is to make a huge overpaneling for my 5,5kW SCC.

I'm planning to build a 10-15kW array.
The Powmr can hande 500V open circut voltage and has a 450V MPPT limit.
I'm planning a max. 360-380V array.
So about 40ampers on full load.
BUT I never use more than 4kW on my output (expect pretty short seconds when for example a compressor start).
So I would never pull 40 amps from my array but about 10-15. I will use only 4kW of power even if my array could produce 10kW.
My inverters manual doesn't mention any input current limit, just an example about max 20amps.

So if my logic is good and everything is built correctly what I willget:
-better yield at winter and cloudy days
-extreme wasted emergy on sunny days
-no problem at all

What you think?
 
Every Solar controller has limits as to the Volts/Watts/Amps they can accept.
That Victron 100/20 will ONLY Accept 100 Volts/1160W from a solar array.
Linking multiple controllers together in parallel then you can use an "Array" of panels for each controller.

Using my system as example again (non Victron but also Tier-1)
Array 1 = 2080W - 4S-2P configuration. Midnite Classic 200 SCC, Takes 200VDC and produces 79A charge.
Array 2 = 2370W - 2S-3P configuration. Midnite Classic 150 SCC, Takes 150V Max & produces 92A charge.
Midnite Systems have HyperVOC to handle over voltage/wattage. Victron does not.
Each array comes in through a Polarized Breaker to SCC, From SCC to another DC Breaker (80A or 100A respectively) then to master E-Panel.

Victron has a tool for working out Panel Combinations to configure your arrays for optimal performance with the selected Solar Controller.
Here is the Link for the tool. USE IT ! A Word, IF you fry an SCC by going overboard - warranty becomes terribly questionable.
www.victronenergy.com

MPPT Calculator - Victron Energy

MPPT Calculator - Victron Energy
www.victronenergy.com www.victronenergy.com

A SOLAR CONTROLLER CANNOT REGULATE INPUT !!! It has no way to throttle it. This is why they are very specific about Max Volts & Watts that it can take. Now I am off to cook some perkolt. Jó napot kívánom, Igen, én is magyar vagyok.
 
timselectric said:
What?
Every single SCC constantly regulates input all day long.
Based on what is available and what is needed.
Click to expand...
Exactly. In principle, the input of the MPPT presents a load resistance between zero and infinite Ohms to maximize the power from the PV.
At either end you get 0 watts, and in-between you get varying power, with its goal to find the maximum power.

Victron recommends you not exceed a specific current level because their reverse-protection circuitry will release the magic smoke.
So don’t connect them backwards!

If you are worried about infinite current from massive over-panelling, do what you always do for large currents: Use a DC breaker or fuse on the PV.
 
I have a victron 150/45 (max power 2600w @ 48V) with an array around 3kw (VOC ~110V, Isc ~40A), fwiw it clips at around 2550w into the battery when the PV would have kept going up, seems happy enough. Also planning to put around 6.5kw on a 250/100 (max 5.6 ish kw). Also notice my goodwe in a different install limit its mppts @ 11A (max rated) fairly regularly. Does it matter how far higher you go? not sure lol
 
An A-Typical SCC will NOT regulate what is incoming if it is Over Spec. They CAN & DO regulate when going from Bulk/Absorb to Float because they take less from the panels and fo all intents & purposes burn off the excess. They Cannot however act a dump loader for overwatt overvolt. Some SCC's Like the Midnite Classics can be used with Wind as well and have the firmware + to support dump load management - with an external dump device (water heater, coil etc).

Given that the OP has such a Large Array, the simplest way to put it, he bought the Wrong Victron SCC and he may have ven been able to use 2-3 or 4 pending on what the panels are and their configuration S & P.
 
Zsiger said:
Is there any chance of the SCC somewhy try to draw more than 20A? Sudden cloud, then back full sunshine or any tracking anomaly? Any danger about it? What about Isc? When will the SCC short circuits the PV input? And why? Because the manual have a max input Isc (20A).
Click to expand...
Here is the Victron discussion on the topic.
General consensus is that the current limit is mainly for reverse polarity protection reasons.
But see for yourself.

SmartSolar Maximum input current - Victron Community

community.victronenergy.com community.victronenergy.com
 
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