Is it okay to exceed max V on an MPPT by 1.2v?

[mjgonsow]

Pictured is a a panel I'm looking at buying 8 of. I'd like to run 2 arrays with them. Each array would consist of 4 in series. I want to run them into my Bluetti AC300 which has a max voltage of 150V and 12A per MPPT controller. If I multiply the Voc by 4 it comes up 1.2v over the max load ... is this little bit going to matter or do I need to find different panels or just run 3 with the panel pictured below?
Thank you again in advance

 

[wiseacre]

run 3 in series - components don't like to be pushed to their limit let alone above it
Also remember that ratings are measured at 25c, VOC rises as temps get lower
While the summer may be somewhat forgiving, winter could easily kill your Bluetti

 

[mjgonsow]

run 3 in series - components don't like to be pushed to their limit let alone above it
Also remember that ratings are measured at 25c, VOC rises as temps get lower
While the summer may be somewhat forgiving, winter could easily kill your Bluetti

Thanks for the info and that is kind of what I was thinking, better to error on the side of safety. I live in Florida so we don't really get winter ... this time of the year I wish we did!

 

[100 Proof]

Thanks for the info and that is kind of what I was thinking, better to error on the side of safety. I live in Florida so we don't really get winter ... this time of the year I wish we did!

You could also run 4 strings of 2 each if you want to use all the panels.

ON EDIT: Nope. It looks like that would blow through the Amp rating. 2 strings of three is indeed the best setup for the AC300 with the panels you have specified.

 

[niktak11]

Some of these power stations work fine running above their advertised max voltage input. Some don't. It's up to you if you want to risk it. I run 3 large panels in series with my AC200P that slightly exceed the 150V stated max input in cold weather and haven't had any issues yet. It's not the end of the world if I break it though.

 

[mjgonsow]

Some of these power stations work fine running above their advertised max voltage input. Some don't. It's up to you if you want to risk it. I run 3 large panels in series with my AC200P that slightly exceed the 150V stated max input in cold weather and haven't had any issues yet. It's not the end of the world if I break it though.

Thanks for the info. The guy I'm buying these panels from has other random sizes, I may see if I can get slightly larger panels and do 2 sets of 3 in series to get closer to the 2400W input. On the flip side slightly smaller panels and do 2 sets of 4 in series.

 

[time2roll]

By design I would be 10% under max voltage.

 

[niktak11]

Thanks for the info. The guy I'm buying these panels from has other random sizes, I may see if I can get slightly larger panels and do 2 sets of 3 in series to get closer to the 2400W input. On the flip side slightly smaller panels and do 2 sets of 4 in series.

If he has 60 cell panels then 3 of them in series should be under the max

 

[73powerstroke]

Pictured is a a panel I'm looking at buying 8 of. I'd like to run 2 arrays with them. Each array would consist of 4 in series. I want to run them into my Bluetti AC300 which has a max voltage of 150V and 12A per MPPT controller. If I multiply the Voc by 4 it comes up 1.2v over the max load ... is this little bit going to matter or do I need to find different panels or just run 3 with the panel pictured below?
Thank you again in advance
View attachment 101575

No

 

[mjgonsow]

No

Are you saying No it's not going to matter if I'm barely over, or No don't do it.

 

[73powerstroke]

Are you saying No it's not going to matter if I'm barely over, or No don't do it.

It'll burn up. No don't do it. You can over panel watts but not voltage

 

[12VoltInstalls]

comes up 1.2v over the max load ... is this little bit going to matter

Don’t go over VOC

 

[fromport]

Pictured is a a panel I'm looking at buying 8 of. I'd like to run 2 arrays with them. Each array would consist of 4 in series. I want to run them into my Bluetti AC300 which has a max voltage of 150V and 12A per MPPT controller. If I multiply the Voc by 4 it comes up 1.2v over the max load ... is this little bit going to matter or do I need to find different panels or just run 3 with the panel pictured below?
Thank you again in advance

There is no need to guess about this

According to this datasheet about those panels

The Voc Temperature Coefficient is -0.27%/°C

Put all data into this calculator:

Maximum Voc And Minimum Vmp Calculator - Ausinet

Calculate the Maximum Voc And Minimum Vmp by this online free calculator The calculator is made as per the Australian Standard AS5033 Clause 3.1 - Free Online Solar Calculator

www.ausinet.com.au

eg: when I enter 3 panels in series, minimum temp -10C/14F I get this results


With 4 panels that would be 165.49 Volts and would be way too high for the input of your electronics.
3 panels max in this case

 

[DThames]

Everyone has already said, "don't do it" but I will add......many chargers have max DC input derated at high ambient. So the 150v max might be 135v if the temp is over 90F, for example. Better to be safely away from that max value.

 

[bgflyguy]

"Don't do it"
But fyi, most electronic components are rated with 5-10% tolerances, and most designs take that in to consideration. However, a lot of the stuff we are buying from China etc. is all over rated by 50-100% or whatever fits the marketing box. That's why the yt testing channels are so popular, imo. I have no idea about the Bluetti specifically, but it is expensive. Maybe film it so if it does go boom, you can get some likes?

If I had to, I would use the calculator above and not run the solar in sunny conditions when the temperature will allow for an over voltage condition. I wouldn't imagine it wouldn't be too often?

 

[DThames]

"Don't do it"
But fyi, most electronic components are rated with 5-10% tolerances, and most designs take that in to consideration. However, a lot of the stuff we are buying from China etc. is all over rated by 50-100% or whatever fits the marketing box. That's why the yt testing channels are so popular, imo. I have no idea about the Bluetti specifically, but it is expensive. Maybe film it so if it does go boom, you can get some likes?

If I had to, I would use the calculator above and not run the solar in sunny conditions when the temperature will allow for an over voltage condition. I wouldn't imagine it wouldn't be too often?

I have toyed with the idea of a voltage clamp on each panel. It wouldn't take but a little load to hold Voc down a little.

 

[rickst29]

I'm strongly within the "don't do it! camp. You appear to be limited to a single string of 3S, due to exceeding the solar VOLTAGE if you add a 4th panel, and also exceeding the Solar CURRENT if you configure a second string. The more costly of those limiting factors is using only a bit more than 8A, out of the 12A rated capacity. There seems to also be a typo, 12A * 150V = 1800 watts (not 2400w). Maybe multiple MPPT units, whose combined output may not exceed 2400 watts into the battery charger? If your strings are running MPPT mode @ 8.5A (or less) * 92 V(mp) volts, (30.7 Volts V(mp) * 3 series panels) your power max power in STC conditions is around 780 watts per string into separate MPPTs, and you could use two of them (for a total around 1560 max solar watts).

 

[mjgonsow]

There is no need to guess about this

According to this datasheet about those panels
View attachment 101636
The Voc Temperature Coefficient is -0.27%/°C

Put all data into this calculator:

Maximum Voc And Minimum Vmp Calculator - Ausinet

Calculate the Maximum Voc And Minimum Vmp by this online free calculator The calculator is made as per the Australian Standard AS5033 Clause 3.1 - Free Online Solar Calculator

www.ausinet.com.au

eg: when I enter 3 panels in series, minimum temp -10C/14F I get this results
View attachment 101637

With 4 panels that would be 165.49 Volts and would be way to high for the input of your electronics.
3 panels max in this case

TYVM, very helpful!

 

[mjgonsow]

I'm strongly within the "don't do it! camp. You appear to be limited to a single string of 3S, due to exceeding the solar VOLTAGE if you add a 4th panel, and also exceeding the Solar CURRENT if you configure a second string. The more costly of those limiting factors is using only a bit more than 8A, out of the 12A rated capacity. There seems to also be a typo, 12A * 150V = 1800 watts (not 2400w). Maybe multiple MPPT units, whose combined output may not exceed 2400 watts into the battery charger? If your strings are running MPPT mode @ 8.5A (or less) * 92 V(mp) volts, (30.7 Volts V(mp) * 3 series panels) your power max power in STC conditions is around 780 watts per string into separate MPPTs, and you could use two of them (for a total around 1560 max solar watts).

Correct, the AC300 has two MPPT controllers and accept a max of 2400W solar input (1200W each) @150V/12A Max per controller as I understand it.

 

[73powerstroke]

I have toyed with the idea of a voltage clamp on each panel. It wouldn't take but a little load to hold Voc down a little.

Just get another charge controller that handle it or run a few panels on a few different controllers. Better safe than sorry