Altitude limits on Inverter/Charter?

[tomrasdf]

Reviewing the documentation for a Growatt inverter/charger that I am about to spec into my build, and am noticing it specifies operating altitude of <2000m (~6,500ft).

(bottom of page 4:
https://signaturesolar.com/content/d...013-manual.pdf

Can't find much on google regarding i) why altitude matters for operation of an inverter/charger or ii) what happens when these limits are exceeded for a few days.

Anyone able to provide any insite?

[fo4imtippin]

Ha. I was just looking at the specs for an MPP which had similar issues. One of my favorite places is summit county Colorado which most of the towns are over 8000ft. I didn't really see an alternative, so was going to just "see what happens".

[ol trunt]

Ask the manufacturer.
Jack

[tomrasdf]

Learned that the altitude spec is due to the fact that arc risk increases as air pressure decreases. Insulation and/or gap size between conductors must increase as altitude increases to provide the same arc suppression. It's a UL thing, which likely means that if your system bombs out above the specified altitude, you are on your own.

I did as the reseller (signature solar) what the risk is, but regardless of what they say, this may push me to pay 2x as much to get a Victron, which appears to be overbuilt such that it does not have an altitude restriction in their spec.

[turf]

very interesting!
thanks for finding out.

that puts about 1/3 of the state of colorado out of limits. (the vacation part)

[TheHubbardBus]

Thanks for this! Learn something new every day

[Tejon7]

Victron components have a maximum altitude as well. I couldn't find it for my older Multiplus, but the fancy new Multiplus II GX has a max altitude of 2000m, just like Growatt you were looking at. See spec sheet HERE - altitude spec is hidden under "Operating Temperature Range".

People use this stuff all the time at high elevations, but maybe you or I will be the unlucky ones who's expensive gear gets fried.

[TheHubbardBus]

If it has to do with arc suppression, I assume (perhaps incorrectly) it's less about the unit functioning properly, and more about preventing radio-frequency interference. Not that the latter isn't important, but maybe not 'lights go out' or 'fires starting' important. I hope someone with more knowledge on the subject can jump in here & confirm. Did the manufacturer give you any insight on this, tomrasdf?

This may be of interest and is kinda related. Arcs can be used for communication, or in modern times, more often as a means of interfering with comms: https://en.wikipedia.org/wiki/Spark-gap_transmitter

[tomrasdf]

Originally Posted by Tejon7

Victron components have a maximum altitude as well.

Interesting.

I didn't see anything related to altitude on their Quattro inverter.

Agreed that if this was a bigger thing, we'd probably have heard more about it by now. Inverters with specified altitude limits are not spontaneously combusting skoolies up and down the continental divide, (or are they?!?).

This may just be a matter of appetite for risk.

[Tejon7]

Whenever I search for info on Victron products, i seem to always find slightly different versions of their spec sheets each time. Not sure why that is... Anyway, THIS particular version of the Quattro datasheet says max elevation 3500m. It's still a limit, but at nearly 11,500 ft it should give you piece of mind nearly everywhere a bus can go. Is it worth the extra money though? I dunno.

[Jolly Roger bus 223]

maybe this is something that is just showing up in the latest and greatest electrical code and its just now getting out to us

[tomrasdf]

The response from Signature Solar:

"That's just the max altitude that they've been tested at. We have people at 8,000+ft using these inverters with success, although you will lose at least 10% efficiency at over 5,000ft according to growatt. This goes for all our inverters at the moment."

Sounds like this is more CYA than safety.

[Veloc]

Has to do with heat. Thinner air can't move as much heat, so an inverter that can cool itself below the specced altitude may overheat when the air is thinner. Put an extra fan in to help blow air through, and if it's outside the living envelope perhaps duct a little cooled air from the AC through it. Alternatively, you can just not draw as much juice through it. Less juice through the inverter is less heat generated.

I wouldn't expect a salesman to know this, or want to pass it on. That's why the weasel words, "tested to but people say..." Use that as a warranty claim and they'll say "tested to means warrantied to, here's the replacement cost but because you've been SUCH a good customer we'll dispose of the old unit for you free of charge."

[TheHubbardBus]

Originally Posted by Veloc

Has to do with heat. Thinner air can't move as much heat, so an inverter that can cool itself below the specced altitude may overheat when the air is thinner. Put an extra fan in to help blow air through, and if it's outside the living envelope perhaps duct a little cooled air from the AC through it. Alternatively, you can just not draw as much juice through it. Less juice through the inverter is less heat generated.

I wouldn't expect a salesman to know this, or want to pass it on. That's why the weasel words, "tested to but people say..." Use that as a warranty claim and they'll say "tested to means warrantied to, here's the replacement cost but because you've been SUCH a good customer we'll dispose of the old unit for you free of charge."

Thanks Veloc!

[PorchDog]

Possibly could build an enclosed cannister to put the inverter in that you could pressurize with Nitrogen to keep it at the maximum altitude pressure allowed....

[Jolly Roger bus 223]

Originally Posted by PorchDog

Possibly could build an enclosed cannister to put the inverter in that you could pressurize with Nitrogen to keep it at the maximum altitude pressure allowed....

is a 2000psi nitrogen bottle at sea level still 2000psi at 8000 feet above sea level?
i dont think it changes but i have seen stranger things?

[HamSkoolie]

Originally Posted by Jolly Roger bus 223

is a 2000psi nitrogen bottle at sea level still 2000psi at 8000 feet above sea level?
i dont think it changes but i have seen stranger things?

AWESOME QUESTION
The answer is largely theoretical (i.e. immeasurable but calculable) because the entire weight of a column of atmosphere is only 14.7PSI so it is miniscule compared to the bottle pressure.


HOWEVER: As the 2000PSI bottle has it's outside pressure reduced, the effect of the atmosphere compressing the bottle against the inside pressing outward is less thus allowing the bottle to expand (ever so slightly). More interior volume means less pressure for a compressed gas such as nitrogen. The effect should be different however should the material inside the pressure vessel be say propane where the pressure is a function of the pressure required to keep the material liquid at a given temperature. If we maintained temperature as we ascend, then the pressure inside a pressure vessel of propane would remain constant as the slight expansion of the vessel would simply allow a little more propane to vaporize inside.


Now, what happens to the human body as we ascend? All kinds of "fun" things. At a certain altitude it doesn't matter how much you breath in or even if you're breathing pure oxygen..... your body cannot absorb oxygen and in fact you're off gassing oxygen from your blood into the air in your lungs and on your way to rapid unconsciousness and death.
Ever been on an airplane flight and suddenly you're drowsy? That's because the airplane cabin is only kept at a pressure altitude of about 8000 feet. This significantly reduces the structural requirements of the pressure vessel that is the passenger cabin allowing for a lighter aircraft.....and more docile passengers. Perhaps we can get them to raise the cabin altitude to 11000 feet?

[HamSkoolie]

Originally Posted by Tejon7

Whenever I search for info on Victron products,...........at nearly 11,500 ft it should give you piece of mind nearly everywhere a bus can go. Is it worth the extra money though? I dunno.

YUP but has nothing to do with the altitude spec.

[HamSkoolie]

Originally Posted by TheHubbardBus

This may be of interest and is kinda related. Arcs can be used for communication, or in modern times, more often as a means of interfering with comms: https://en.wikipedia.org/wiki/Spark-gap_transmitter

As HAM radio operators..... the "Spark Gap" was a legitimate means of communication via Morse code many years ago.
Today, you can build one quite cheaply..... but you will get a visit from one or more disgruntled HAM's if not the FCC themselves fairly soon.


And yes, want to send a drone home? Establish a powerful arc production device and it will jam the entire RF spectrum causing loss of communications with the control unit and even low end drones will resort to "auto return" until communications can be re established with the control unit.
Probably not super effective on military gear (or our Drones would have been ineffective in the middle east) but that DJI Phantom hovering over your teenage daughter sunning in the back yard? Just maybe.

[Jolly Roger bus 223]

once again ham.
oohrah.
i do heating and air for a living and know the specific weight of water, propane, and natural gas but never thought about altitude pressure changes? thats easy enough for water pressure but never thought about pressuried gas.
other than military flight the farthest north i have ever been was york pa and that wasnt very long. in and out and back to lejeune