Victron MPPT solar array help please

[brackstone]

Hello All

I have a Victron 150/45 MPPT charging a 48v system. Currently I have 6 x 300 Watt panels connected as two strings in parallel. So I end up with 102v with 1800 Watts.

My solar array is not installed in an ideal perfect location and has some shading so on a good day I am lucky to get 20A out of the controller.

My question is how to get more without having to change the controller and current panels.

If I add another 3 x 300Watt panels in parallel I will get the same voltage which is ok for the controller but will be at 2700 watts. The Victron manual specifies max 2600 watts, but my theory is that seeing as my system is not ideal and will never get to full potential will this actually cause an issue with the controller.

I expect with an extra 900 watts I will be getting 30A max so then I could go further and put 1800 Watts to get 40 amps out of the controller. This will be a max 3600 watts array but the controller will not see the full potential.

i understand the ideal solution if to buy a bigger MPPT but need to keep to some sort of budget

 

[timselectric]

What you are describing is called "overpaneling" (making more solar amps available) , and a common practice.
Current isn't pushed, it must be drawn. So making more available doesn't hurt anything (as long as you never connect in reverse polarity). But at some point too much can get wasteful.

 

[brackstone]

What you are describing is called "overpaneling" (making more solar amps available) , and a common practice.
Current isn't pushed, it must be drawn. So making more available doesn't hurt anything (as long as you never connect in reverse polarity). But at some point too much can get wasteful.

Great thats interesting I thought over powering would overheat the controller.

I know I should keep within the MPPT voltage limit.

So I may go ahead and look into increasing the solar array.

Thanks

 

[Madcodger]

It ain't the amps that summon the magic smoke from a charge controller, but rather the volts. Step into the land of extra potential amps to your heart's desire. But step even a tiny little bit into the land of too many volts, and the magic "gotta buy a new charge controller" smoke appears. You don't want that smoke.

 

[ricardocello]

Great thats interesting I thought over powering would overheat the controller.

Oh, it will definitely be hot running at max power output, but it is designed for that.

Adding more panels will not make it any hotter.
Except that the time running at max power will be lengthened.

As Tim said, at some point it becomes wasteful and you are better off with a second or a bigger MPPT.

 

[Suijkerbuijk]

Can you set picture of your Setup.
Its strange that you are on that low ampère
Theorie you can do about 35a .

What float charge u using ?
I had to set my on 14volt on a 12 volt systeem that the Controller stay charge on the max from the panel .
Wel i set the float advice on 13.5volt it will not charge on the max
In your case will the float be around 46 volt ?
Just adjust it little higher stap by stap and see how your charger will function.

 

[brackstone]

Oh, it will definitely be hot running at max power output, but it is designed for that.

Adding more panels will not make it any hotter.
Except that the time running at max power will be lengthened.

As Tim said, at some point it becomes wasteful and you are better off with a second or a bigger MPPT.

My main issue is the panels are set at a very low angle and have two with tree shading. Extra panels will boost the wattage and charge current. If I add a second controller it will be the same issue but more expense. I think I will try the third 900 watt array and if this does not get more then I will look into a second controller

 

[740GLE]

Trees are cancer, you cut out the cancer, just saying

Can you post the specs of the panels?

3s for a 300w panel could have VOC 30-45 which maybe tickling the VOX max of the 150 MPPT

Your report of seeing 100v from the array, is that when the MPPT is working or measured for VOC?

 

[brackstone]

Trees are cancer, you cut out the cancer, just saying

Can you post the specs of the panels?

3s for a 300w panel could have VOC 30-45 which maybe tickling the VOX max of the 150 MPPT

Your report of seeing 100v from the array, is that when the MPPT is working or measured for VOC?

panel spec

• Max Current (Imp) 11.8A
• Max Voltage (Vpm) 27.9V
• Short Circuit Current (Isc) 12.6A
• Open Circuit Voltage (Voc) 34.1V

This is measures voltage around 102V which has been running for over a year now but not great in low sun and very poor in winter.

Solar download of the controller attached.

Trees are in the grave yard next door so not sure they will like me cutting them down

 

[740GLE]

panel spec

• Max Current (Imp) 11.8A
• Max Voltage (Vpm) 27.9V
• Short Circuit Current (Isc) 12.6A
• Open Circuit Voltage (Voc) 34.1V

This is measures voltage around 102V which has been running for over a year now but not great in low sun and very poor in winter.

Solar download of the controller attached.

Trees are in the grave yard next door so not sure they will like me cutting them down

Those panels look perfect for a 3S for a 150v controller.

If you go for 3 parallel strings you’ll still be under the max short circuit of the current.

What size conductor to you have going from the array to the SCC? Would you need to upsize adding another 12-13a? You’d have a total of what 35-40a?

Play the long game, a couple selective cuts made over the course of a month and the problem will take care if itself next wind event.

 

[brackstone]

Those panels look perfect for a 3S for a 150v controller.

If you go for 3 parallel strings you’ll still be under the max short circuit of the current.

What size conductor to you have going from the array to the SCC? Would you need to upsize adding another 12-13a? You’d have a total of what 35-40a?

Play the long game, a couple selective cuts made over the course of a month and the problem will take care if itself next wind event.

I know the VOC will be OK for the controller and I have 6mm cables so Voltage drop is all ok and current capacity of the wiring is OK.

The issue is with the location I live more north of the equater, the angle of the solar array, almost flat and shading.

I am getting the max out of the current 1800 watts which would give more in ideal conditions. So my only solution would be to add more Solar or a new array with controller

 

[Boomerweps]

Don’t forget to allow for cold weather increases in panel efficiency. That is when overpaneling can be a problem. IIRC, there is a good research paper here on over paneling. If not, on the Victron website.

 

[sunsurfer]

My main issue is the panels are set at a very low angle and have two with tree shading. Extra panels will boost the wattage and charge current. If I add a second controller it will be the same issue but more expense. I think I will try the third 900 watt array and if this does not get more then I will look into a second controller

If you have shading that only affects a couple of panels at a time and there is no way of fixing the shading, you could consider breaking down your strings so the shaded panels dont drop out the non shaded panels in a big string.

You would need smaller strings with multiple controllers. This works as the shade moves around to each separate string.. Think 2-4 panels per string. Not ideal but you will get more power. Down side is you have to run all the extra wire.

 

[brackstone]

Don’t forget to allow for cold weather increases in panel efficiency. That is when overpaneling can be a problem. IIRC, there is a good research paper here on over paneling. If not, on the Victron website.

I will have a look, I thought cold weather will only increase panel voltage to max. So i should be OK being 45v below max for the controller

 

[cs1234]

I will have a look, I thought cold weather will only increase panel voltage to max. So i should be OK being 45v below max for the controller

Cold weather increases panel VOC by the rate specified per degree on the panel specs. I'm not sure there is technically a limit for how high the panel voltage could go, aside from the panel shattering from some super freezing non earth like temperature. I guess the voltage would be limited by whatever the maximum cold temperature of our Universe happens to be.

 

[timselectric]

Don’t forget to allow for cold weather increases in panel efficiency. That is when overpaneling can be a problem.

Overpaneling only refers to amperage. (Never Voltage)
Voltage can be a problem in cold temperatures, if not accounted for.

 

[740GLE]

I will have a look, I thought cold weather will only increase panel voltage to max. So i should be OK being 45v below max for the controller

VOC is at like 25c, it drops on a scale provided by the spec sheet. so if the lows are say -10c it might rise a bit say a couple volts or so.

But with a VOC 34v there’s no chance you’re local temps would bring that up to 50v which would be the max for a 3a string.