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I'm confused on victron mppt 150/45 solar limits

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oregonsun

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I searched and can't find the answer, even though I'm sure it's probably been answered a million times.

I bought a smartsolar 150/45 and I guess I need to know what the overpanel limits are.

The specs for it say 150v input max and 50a input current, which leads me to calculate 7500w max panels but obviously the specs don't agree and say it's limited to 2600w at 48v.
Curious

I live in Oregon and need max performance in low light and cloudy conditions so I want to overpanel as much as I can.

Is it ok to connect 8x 440w panels in 2s4p which adds up to 3200w max? 49.5voc 10.5a isc per panel which equals around 100v 42a?

Am I right to assume there's no way it can do 9x 440w panels in 3s3p, even if I add long leads to intentionally add voltage drop, that the voltage could still exceed max in cold conditions?
 
Last edited:
45 x Battery Voltage = Peak Solar watts...anything over is over paneling.
 
oregonsun said:
The specs for it say 150v input max and 50a input current, which leads me to calculate 7500w max panels but obviously the specs don't agree and say it's limited to 2600w at 48v.
Curious

I live in Oregon and need max performance in low light and cloudy conditions so I want to overpanel as much as I can.
Click to expand...

The 150 volt limit is the open circuit voltage, You'll get a maximum power point voltage of around 100 if your open circuit voltage is just under 150. So you can only over panel it to about 5,000 watts.

Don't think of it as how much over you can go over on one charge controller. If you can fit and afford 5,000 watts of panels, and you have enough batteries to charge in the 100 amp range. Just get a second charge controller. and split the panels between the two.

If you happen to get a NICE SUNNY day and your batteries are low, do you really want to limit your charging by only having one charge controller?
 
Maximum practical limit on that controller is 3S of 60 cell panels with 50A input current limit, so:

93V * 50A = 4650W

The 2600W is an OUTPUT based on:

45A * 58V = 2610W

2S4P is fine.

For reference:

www.victronenergy.com

Matching solar modules to MPPT charge controllers - Victron Energy

Life used to be so simple; in a 12V battery system you took a ‘12V’ solar module, watched carefully that the maximum PV current would not exceed the charge controller maximum current and the system would work. Unfortunately due to the fact, that with PWM controllers the PV module is not feeding...
www.victronenergy.com www.victronenergy.com

Limits to Oversizing a PV array

How to determine by how much you can oversize a PV array? This can be done with help from the spreadsheet tool. Here though is the manual explanation of how it is done.

There are two limits, when determining the maximum array size that can be connected to an MPPT:
  1. The Maximum PV open circuit voltage (Voc at STC)
  2. The Maximum PV short circuit current (Isc at STC)
Both values are specified in the datasheets of all our MPPT Solar Charge Controllers. Those two ratings of the PV array must not exceed these MPPT limits.

Note that these two maximum ratings must not be multiplied to determine the maximum installable peak power. Instead, each of them needs to checked by itself:

As an example, if I were silly enough to have my 250/100 on a 12V system, while it could only OUTPUT 100A * 14.5V = 1450W, it could have 5S 60 cell panels at about 180Vmp and 70A input limit, 180*70 = 12,600W array. Kinda wasteful, but it's permitted. Would output 100A almost all day long.
 
sunshine_eggo said:
Maximum practical limit on that controller is 3S of 60 cell panels with 50A input current limit, so:

93V * 50A = 4650W

The 2600W is an OUTPUT based on:

45A * 58V = 2610W

2S4P is fine.

For reference:

www.victronenergy.com

Matching solar modules to MPPT charge controllers - Victron Energy

Life used to be so simple; in a 12V battery system you took a ‘12V’ solar module, watched carefully that the maximum PV current would not exceed the charge controller maximum current and the system would work. Unfortunately due to the fact, that with PWM controllers the PV module is not feeding...
www.victronenergy.com www.victronenergy.com

Limits to Oversizing a PV array

How to determine by how much you can oversize a PV array? This can be done with help from the spreadsheet tool. Here though is the manual explanation of how it is done.

There are two limits, when determining the maximum array size that can be connected to an MPPT:
  1. The Maximum PV open circuit voltage (Voc at STC)
  2. The Maximum PV short circuit current (Isc at STC)
Both values are specified in the datasheets of all our MPPT Solar Charge Controllers. Those two ratings of the PV array must not exceed these MPPT limits.

Note that these two maximum ratings must not be multiplied to determine the maximum installable peak power. Instead, each of them needs to checked by itself:

As an example, if I were silly enough to have my 250/100 on a 12V system, while it could only OUTPUT 100A * 14.5V = 1450W, it could have 5S 60 cell panels at about 180Vmp and 70A input limit, 180*70 = 12,600W array. Kinda wasteful, but it's permitted. Would output 100A almost all day long.
Click to expand...

I‘m asking as I am trying to learn something here & reading specs sometimes I literally “don’t understand”;


Your example of having 5S & 70A but input ?


IMG_0202.jpeg


Is that an issue for the MC4 connection ? (Victron states 30A max)

IMG_0203.jpeg
 
kayakingphotos said:
The 150 volt limit is the open circuit voltage, You'll get a maximum power point voltage of around 100 if your open circuit voltage is just under 150. So you can only over panel it to about 5,000 watts.

Don't think of it as how much over you can go over on one charge controller. If you can fit and afford 5,000 watts of panels, and you have enough batteries to charge in the 100 amp range. Just get a second charge controller. and split the panels between the two.

If you happen to get a NICE SUNNY day and your batteries are low, do you really want to limit your charging by only having one charge controller?
Click to expand...

This is what I was missing in my confusion, I forgot/didn't actually realize how much the voltage drops under load.

I will eventually get another controller but that has to wait, I've been buying a ridculous amount of stuff lately and just can't spend any more atm.

I already have the panels but am forced to switch from using a growatt to get away from the high idle consumption which is absolutely killing me now in winter.

I do have two smartsolar 100/20 though that I also grabbed while they are on sale, to manage other 100w panels I have, is there any way to use one of them for some of these 440w panels with a VOC of 49.5v in 2s2p, still wondering if I can just deliberately cause a little voltage drop so they don't exceed the controller voltage limit. They're so close to exceeding the limit at 99v with two in series, but I still feel like if I just add 50-100 feet of wire between them and the controller maybe that would drop the voltage enough to use one?

I do have enough batteries to feed all this power into, 25kw of lifepo4 now. :) Probably way more than I need for this setup but half of them were free.
 
Last edited:
RV8R said:
I‘m asking as I am trying to learn something here & reading specs sometimes I literally “don’t understand”;


Your example of having 5S & 70A but input ?


View attachment 177481


Is that an issue for the MC4 connection ? (Victron states 30A max)
Click to expand...

MC4 connectors themselves are typically limited to 30A. My particular unit doesn't have MC4 connectors (Tr version). The 250/100 MC4 has 3X MC4 pairs on it, so even though each MC4 is rated for 30A which implies 90A, the unit is limited to 70A.
 
RV8R said:
I‘m asking as I am trying to learn something here & reading specs sometimes I literally “don’t understand”;


Your example of having 5S & 70A but input ?


View attachment 177481


Is that an issue for the MC4 connection ? (Victron states 30A max)

View attachment 177476
Click to expand...

I don't have any answer for you but "Would output 100a all day long"... Not where I live in the winter, I'm lucky to get 2KW from around 5500w of panels after an entire day of rain and clouds, which is the reason I've had to switch from using the growatt, it's idle consumption was greater than my entire days harvest of solar on most winter days.

Oregon in winter is mostly cloudy and rainy and I don't have a place to mount the panels, they're still flat on the ground until I get some exterior house painting and siding repair done.
 
oregonsun said:
I do have two smartsolar 100/20 though that I also grabbed while they are on sale, to manage other 100w panels I have, is there any way to use one of them for some of these 440w panels with a VOC of 49.5v in 2s2p, still wondering if I can just deliberately cause a little voltage drop so they don't exceed the controller voltage limit. They're so close to exceeding the limit at 99v with two in series, but I still feel like if I just add 50-100 feet of wire between them and the controller maybe that would drop the voltage enough to use one?

I do have enough batteries to feed all this power into, 25kw of lifepo4 now. :) Probably way more than I need for this setup but half of them were free.
Click to expand...
NO

Open circuit voltage is there when Zero Current is flowing. With no current flowing, there is no voltage drop no matter the length of the wire.

You will be over 100 volt open circuit almost all the time if you wire them as 2s.

The Victron MPPT calculator linked above will show you the open circuit voltage compensated for temperature if you input all the panel specifications.
 
sunshine_eggo said:
MC4 connectors themselves are typically limited to 30A. My particular unit doesn't have MC4 connectors (Tr version). The 250/100 MC4 has 3X MC4 pairs on it, so even though each MC4 is rated for 30A which implies 90A, the unit is limited to 70A.
Click to expand...

Thanks @sunshine_eggo

I am a novice & have a very small system 6 - 100W Array which is 3S2P; so basically 60volts & 10amps = 600W.

Victron 100 | 50 & on a 12vdc AGM ( 250Ah ).



Have you ever gone thru a learning process & the penny has dropped, but only partially?? That is where I am at ?.

That is how I feel about my understanding from your posts on this thread & part of it is I have zero experience with the bigger equipment.

My question(s) is not “Your“ actual system I am asking about, but that example you stated;

IMG_0202.jpeg


I assume ”in your example” the 5S1P provides an Array of 180volts @ 70amps = 12600W ?

So those panels are “singularly” 70amps each? As they are on 1 string?

So if MC4 are good for 30amps & 10AWG also has it limits, are MC4s “not used” on the solar panels or anywhere in that 1 string system? So the Solar panels are 70amps as single panels & do not come with MC4 pigtails ( + & - )?


Then in my case with my Victron 100 | 50 ; Can I over panel by staying safely under the 100 max voltage, but increasing the input amps to 50 ? Say an array of 70volts @ 50amps ?

If I do that then do I wire it differently without any MC4s?

What is a (Tr version)? I will try to google this


Sorry for all the questions, but I do appreciate your posts here as it has greatly helped my limited understanding.


edit; so 2 models of the 250 | 100 ,,, Tr & MC4


IMG_0208.jpeg

IMG_0209.jpeg


Seems to be an option after the 50 amp size ?‍♂️
 
Last edited:
sunshine_eggo said:
There are two limits, when determining the maximum array size that can be connected to an MPPT:
  1. The Maximum PV open circuit voltage (Voc at STC)
  2. The Maximum PV short circuit current (Isc at STC)
Click to expand...
What are the current limits of over paneling?
 
kayakingphotos said:
NO

Open circuit voltage is there when Zero Current is flowing. With no current flowing, there is no voltage drop no matter the length of the wire.

You will be over 100 volt open circuit almost all the time if you wire them as 2s.

The Victron MPPT calculator linked above will show you the open circuit voltage compensated for temperature if you input all the panel specifications.
Click to expand...

I had to google what you said there about no voltage drop without current flowing, I do not remember that from college I took decades ago for electronics field service. You're right. Dang. My memory is just not so good any more.
 
RV8R said:
Thanks @sunshine_eggo

I am a novice & have a very small system 6 - 100W Array which is 3S2P; so basically 60volts & 10amps = 600W.

Victron 100 | 50 & on a 12vdc AGM ( 250Ah ).



Have you ever gone thru a learning process & the penny has dropped, but only partially?? That is where I am at ?.

That is how I feel about my understanding from your posts on this thread & part of it is I have zero experience with the bigger equipment.

My question(s) is not “Your“ actual system I am asking about, but that example you stated;

View attachment 177508


I assume ”in your example” the 5S1P provides an Array of 180volts @ 70amps = 12600W ?

So those panels are “singularly” 70amps each? As they are on 1 string?

So if MC4 are good for 30amps & 10AWG also has it limits, are MC4s “not used” on the solar panels or anywhere in that 1 string system? So the Solar panels are 70amps as single panels & do not come with MC4 pigtails ( + & - )?


Then in my case with my Victron 100 | 50 ; Can I over panel by staying safely under the 100 max voltage, but increasing the input amps to 50 ? Say an array of 70volts @ 50amps ?

If I do that then do I wire it differently without any MC4s?

What is a (Tr version)? I will try to google this


Sorry for all the questions, but I do appreciate your posts here as it has greatly helped my limited understanding.


edit; so 2 models of the 250 | 100 ,,, Tr & MC4


View attachment 177513

View attachment 177514


Seems to be an option after the 50 amp size ?‍♂️
Click to expand...
The Tr is the bare wire (screw terminal) version. The MC has two or three pairs of MC4 (paralleled internally). Potentially you could avoid using a combiner box or something with the MC version.
 
And remember name plate PV watts output is only a tested value that’s hard to achieve for time that’s worth while.

I’d much rather have 1.5 PV name plate going into my SCC knowing that I’d be leaving 10-20% peak output on the table (for an hour or two a day) and capture more power over the course of the entire day.
 
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