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Victron MPPT over panelling

timselectric said:
Again, multiple battery voltages.

I still think that my original statement stands true.
You have to be careful with overpaneling Victron SCC's. Too many amps will damage them.
Unless I misunderstood previous conversations on how they operate.
Click to expand...

Then why do Victron even have an option for "Allow oversizing above 130%" on their MPPT calculator...

www.victronenergy.com

MPPT Calculator - Victron Energy

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

If it were simply do not exceed max voltage and input amps then they wouldn't even talk about oversizing. (the SCC would simply go up in a puff of smoke the moment maximum inputs were exceeded)

No, oversizing is in relation to the watts of PV relative to the max wattage output of the unit.
 
timselectric said:
It was my understanding that they very well could.
If input amperage was exceeded.
@sunshine_eggo please correct me if I'm wrong.
Click to expand...

Of course they would. That's why they state not to go over the maximum voltage rating and amperage input rating.

But that's not what they're talking about when they talk about oversizing PV relative to the SCC output.
 
I run my 75/15 with PV input connected to 630Ah battery, so it's effectively as overpaneled as wire resistance will allow. I have 5A fuse in line. It never blew yet. So I kinda doubt Victron shorts PV input as part of MPPT routine. Or maybe MPPT never runs when it detects "infinite" power source. Makes this thing into neat little 48V > 12V dc converter with bluetooth!
 
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timselectric said:
You have to be careful with Victron SCC's.
They aren't like other MPPT's.
Part of their sweep includes shorting the circuit.
They are very limited with overpaneling.
Click to expand...

It was these parts. Victron provides very clear guidance on over-paneling their MPPT. Their MPPT calculator regularly recommends up to 30% over-paneling just because you're not missing much in most cases.

While a 250/100 (what I have) could only put out 1450W to a 12V battery, one could safely hang about about 11,000W@ 170Vmp and 65A Imp. That's over 700%.

It gets even more absurd with the 450/200. EACH tracker (4) can safely be over-paneled to about 8,300W... there's 4 trackers, so about 33kW even though it can only output about 11kW.

timselectric said:
It was my understanding that they very well could.
If input amperage was exceeded.
@sunshine_eggo please correct me if I'm wrong.
Click to expand...

Kiwi2000 said:
Of course they would. That's why they state not to go over the maximum voltage rating and amperage input rating.

But that's not what they're talking about when they talk about oversizing PV relative to the SCC output.
Click to expand...

Nope. The PV input current limit is the maximum Isc the array can have and still retain reverse polarity protection. If you don't hook your array up backwards, then there's no hard limit - except on the aforementioned RS 450/200 (they explicitly state it's a hard limit).

It probably runs up against a sanity limit. It would be insane to put 30kW on a controller only capable of outputting 5800W :)
 
I overpanelled a cheap renogy 40 amp to probably 5x its limit. I had 10 panels on it and disconnected them 1 by 1 until it was just two panels pushing it to 42 amps. So it had handled the extra 8 just fine.?

It output 42 amps and just got warm/hot and kept on ticking. I would guess it's heat rejection was in the order of 50-70 watts.

My current Epever was at 12 volts 100 amp is sitting on 2470 of panels.

Same deal 1 sunny day in July. It just kept it to like 98 amps while the panels went to full open circuit voltage. Controller gets warm but nothing to write home about.
 
timselectric said:
I guess that I was misunderstood.
Overpaneling (to most) means exceeding amperage limits.
But, I suppose the word could also be used for exceeding wattage rating. While remaining below VOC and ISC of controller.
I would not consider that Overpaneling. Because you are within the two limits.
Click to expand...
So in your world over paneling is a 30A SCC outputting more than 30a?!? Or just an SCC allowing higher VOC than published specs, like midnites?

I always thought over paneling was just having more name plate PV connected to the SCC than it could output.

Do all SCC post ISC limits?
 
740GLE said:
So in your world over paneling is a 30A SCC outputting more than 30a?
Click to expand...
No
I would assume that is impossible.
740GLE said:
Or just an SCC allowing higher VOC than published specs,
Click to expand...
Never
740GLE said:
I always thought over paneling was just having more name plate PV connected to the SCC than it could output.
Click to expand...
This basically.
But since Victron has multiple voltage output options. It appears that it has multiple options for overpaneling. As long as you never exceed the ISC hard limit.
740GLE said:
Do all SCC post ISC limits?
Click to expand...
Nope, only a few post hard limits.
 
Checkthisout said:
I overpanelled a cheap renogy 40 amp to probably 5x its limit. I had 10 panels on it and disconnected them 1 by 1 until it was just two panels pushing it to 42 amps. So it had handled the extra 8 just fine.?

It output 42 amps and just got warm/hot and kept on ticking. I would guess it's heat rejection was in the order of 50-70 watts.

My current Epever was at 12 volts 100 amp is sitting on 2470 of panels.

Same deal 1 sunny day in July. It just kept it to like 98 amps while the panels went to full open circuit voltage. Controller gets warm but nothing to write home about.
Click to expand...
Last winter I had 90a worth a panels connected to an 18a SCC. I had full output from sunrise to sunset. lol
 
timselectric said:
No
I would assume that is impossible.

Never

This basically.
But since Victron has multiple voltage output options. It appears that it has multiple options for overpaneling. As long as you never exceed the ISC hard limit.

Nope, only a few post hard limits.
Click to expand...
So what’s your definition of over paneling?

Do you have your favorite SCC that you consider over paneling friendly?
 
740GLE said:
So what's your definition of over paneling?
Click to expand...
Connecting more PV than a SCC can use.
Since most MPPT's have voltage and amperage limits that closely add up to the wattage. It usually means over amperage. (Since overvoltage is damaging)
740GLE said:
Do you have your favorite SCC that you consider over paneling friendly?
Click to expand...
Most are, if they don't post hard ISC limits.
I know that my Growatt's have no problem with it.
And members have reported several others. I don't remember exactly which ones they were. But I'm sure that all of the Voltronics based ones are fine with it.
 
Any well designed MPPT controller should have output overcurrent protection or any software glitch will let the smoke out. It should only drink what it needs from the firehose.
 
Wow

My most replied to thread too date !!!!

I started this topic, simply on the assumption that I trusted my TriStar mppt over the possible new addition of a victron.

(I have a TriStar 45a mppt and wanted to add a 20a mppt and found a good deal on the Victron)

This is all a assumption mind
But TriStar controller are a lot more money than vicron

If TriStar gives a limit of 130% too over panelling (ie wattage not voltage) then why does the cheaper victron not mention it other then so say the mppt will deal with it

That was my logic that prompted my question
 
You can over-panel Victron SCC as much as technically possible, that is, within its Voc and Isc limits.

I have Victron 100/20@12V(290W max) currently, and with enough panels, I could go and over-panel it by 500% or 1600W of solar in summer or 400% in winter.

Obviously, I'd never go with 500% as it matches the SCC Voc, but even 400% over paneling is a lot on this small 100/20 beast.

As Sunshine mentioned, you could even over-panel a bit more over the Isc limit, but in case of reverse polarity or short-circuiting of the PV input, the SCC can no longer protect itself.

So, staying within Voc and Isc limits with a bit of headroom is the best practice.
 
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I've spent quite a bit of time going through hundred of solar panel datasheets to find a good panel match for this SCC that would enable me to fully utilize this small SCC beast.

Two panels are a darn near perfect match for this SCC, depending on what you have to work with space-wise, temperatures, etc.

So without further ado, here's what I've found to be a good match for this SCC.

A more elegant combo is 100/20 with 3x Sunpower Maxeon3 400w panels in parallel for a total of 1200W
Voc 75.6V & Isc 6.58A per panel.

A more flexible combo, 100/20 with 12x Ecoflow Rigid 100W solar panels in 4S3P configuration
Voc 20,3V & Isc 6.3A per panel.

Ecoflow 100W rigid panel
- almost universally available across the globe
- reasonable price, ability to order online with free shipping mostly
- well protected in the box
- each set of two has a sticker on the box with two SN for each panel so you can activate warranty on their official website.
- since it's a part of the whole line of products it's intended for, there's a certain guarantee you'll be able to add more of the same panels going forward with no concerns will it be available in a few years as with some or most of the other panels. So you don't have to buy 12x panels from the get-go, you can do so in steps.

Anyhow, hope it helps shed light on what panel might be worth considering if you're looking to get the most out of Victron 100/20.
 
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sunshine_eggo said:
The PV input current limit is the maximum Isc the array can have and still retain reverse polarity protection. If you don't hook your array up backwards, then there's no hard limit - except on the aforementioned RS 450/200 (they explicitly state it's a hard limit).
Click to expand...

Is there any truth to what previous posts in this thread have said about the MPPT sweep and that it includes a short circuiting of the array? It seems strange to me if it was, because what useful data can the controller get from that? If I'm correct, then there is no real limit to array short circuit current either, as long as you put a fuse in series with the array.

As far as I understand, if the controller senses something dangerously wrong with the array it can go into protective mode and short circuit the array to protect itself and other connected devices. That's where I think the max Isc value comes from. Is that correct?
 
BjornM said:
That's where I think the max Isc value comes from. Is that correct?
Click to expand...
I think that's correct. Max Isc rating is relevant to how many amps controller will tolerate when PV is connected in reverse polarity. When that happens there is internal diode that short circuits the panels to protect remaining circuitry.
 
AntronX said:
I think that's correct. Max Isc rating is relevant to how many amps controller will tolerate when PV is connected in reverse polarity. When that happens there is internal diode that shorts circuits the panels to protect remaining circuitry.
Click to expand...

So as long as you don't crimp black to red you can overpanel by quite a bit?
 
Yes I think so. I run my Victron smart solar 75/15 from 44V 630Ah battery bank connected to PV input via 5A fuse. It never failed.

Screenshot_20240121-131613.jpg Screenshot_20240121-131649.jpg
 
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BjornM said:
Is there any truth to what previous posts in this thread have said about the MPPT sweep and that it includes a short circuiting of the array? It seems strange to me if it was, because what useful data can the controller get from that? If I'm correct, then there is no real limit to array short circuit current either, as long as you put a fuse in series with the array.

As far as I understand, if the controller senses something dangerously wrong with the array it can go into protective mode and short circuit the array to protect itself and other connected devices. That's where I think the max Isc value comes from. Is that correct?
Click to expand...

I need some education here.

I thought "shirt-circuiting the array" means it will momentarily connect the battery directly to the array to see if array voltage will pull down to battery voltage.

Now I feel like an idiot.

So the controller has some circuitry at the PV input that allows direct shorting of the solar pos/neg?
 
BjornM said:
Is there any truth to what previous posts in this thread have said about the MPPT sweep and that it includes a short circuiting of the array? It seems strange to me if it was, because what useful data can the controller get from that? If I'm correct, then there is no real limit to array short circuit current either, as long as you put a fuse in series with the array.

As far as I understand, if the controller senses something dangerously wrong with the array it can go into protective mode and short circuit the array to protect itself and other connected devices. That's where I think the max Isc value comes from. Is that correct?
Click to expand...

Shorting is not a normal function UNLESS reverse polarity is detected. Hence the limit.

Still can't believe they don't have voltage sense leads... :p
 
AntronX said:
I think that's correct. Max Isc rating is relevant to how many amps controller will tolerate when PV is connected in reverse polarity. When that happens there is internal diode that short circuits the panels to protect remaining circuitry.
Click to expand...

Here is what it says in the SmartSolar 250/100 manual (might be different from the model this thread is about).

8.10.5. PV Short relay reset procedure
This procedure outlines the reset process for the internal protection mechanism, known as the PV Short Relay, in the Smart SolarCharger 250/100.The protection consists of a latching relay, which is mounted across the PV Input. When the firmware detects a short between the PV inputs and the battery outputs, by monitoring the battery voltage for an over-voltage, it engages the relay and, as such, shorts the PV Input.

8.11.15. Error 80 to 88 - PV Input shutdown
When these errors show, the PV Input is internally shorted in order to protect the battery from over-charging.

And in the specs for max 70 A short circuit current, it also says "A higher short circuit current may damage the solar charger in case of reverse polarity connection of the PV array", just like you mentioned.

So I assume the Isc current limitation is for both the reverse polarity protection and the short relay.
 
Checkthisout said:
I thought "shirt-circuiting the array" means it will momentarily connect the battery directly to the array to see if array voltage will pull down to battery voltage.
Click to expand...

It is the opposite of that. It connects the two input leads from the solar array together (short circuits them), so that no current can flow from the array to the battery.
 
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