Altitude rating on Inverters

Just curious about the max altitude rating on inverters. I am at 8000'+ elevation (about 2500m), and it seems several of the popular AIO inverters are rated up to 2000m, a few for 3000m. The only thing which it seems might be effected by altitude is cooling efficiency with the thinner air, which while real is less of a concern up here most of the time because we tend to be much cooler than at lower elevations (and all the units should be monitoring their internal temps). I suppose it might also be possible that some of the capacitors may have leaking issues at higher elevations too.

I am just wondering how seriously I need to "obey" these limits. Can anyone comment about this. Any other potential issues that might come into play?

Steve777 said:

Can anyone comment about this. Any other potential issues that might come into play?

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It's not so much cooling efficiency but when air is at less pressure the insulation breakdown voltage becomes less.

So it's down to PCB design (gaps between tracks), coatings etc. i.e. insulation resistance vs. humidity.

Presumably the cheaper ones are not rated for higher altitudes.

IIRC @Hedges is the expert on these matters on here.

I'm not quite an expert on it, but have absorbed some knowledge by osmosis while working as an Aerospace Engineer. Thinking about failures during transient overvoltage, etc. I did manage to apply my physics classes to estimating breakdown vs. dimensions of sealed connectors, considering defect size.


Yes, I used to think it was just cooling, but realized/discovered it is breakdown voltage of air at reduced pressure (look up Paschen curve).

I'm thinking maybe the inverters designed for 230V then changed for 120V market (e.g. Sunny Island) may have more margin. Depending on what they changed.

If strictly off-grid, the gaps needed for grid connected (with its kV spikes) probably don't apply. But we don't know what other pins have issues.

As SeaGal said, coatings like Parylene should help. Higher quality equipment has coated PCB. Some are potted (Victron SCC, I think.)

I've pondered was to mitigate. Seal and pressurize? (could put in an external sealed box, have to deal with cooling.) Fill with SF6? (we don't care about global warming potential anyway.) Wondering if R410a or similar refrigerant would be good, have to find Paschen curves.
Any gas fill would be for something with sealed inner volume, fan cooling if any outside. Like SMA's Opticool, or Outbacks GFX (not GVFX).

Steve777 said:

Just curious about the max altitude rating on inverters. I am at 8000'+ elevation (about 2500m), and it seems several of the popular AIO inverters are rated up to 2000m, a few for 3000m. The only thing which it seems might be effected by altitude is cooling efficiency with the thinner air, which while real is less of a concern up here most of the time because we tend to be much cooler than at lower elevations (and all the units should be monitoring their internal temps). I suppose it might also be possible that some of the capacitors may have leaking issues at higher elevations too.

I am just wondering how seriously I need to "obey" these limits. Can anyone comment about this. Any other potential issues that might come into play?

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So far, it looks like Sungold is rated to 9,800 feet above sea level. It never dawned on me that there was any issues with altitude. I have a MagnaSine 2kw that we have used for three years at 9,600 feet and have had no issues. But I am wanting to up grade to a 5kw+ system. And I ran into the same information wall that you did. So far, this forum has been the only source of a scientific explanation. Thank you for your post. Any guidance of what’s the best route is genuinely appreciated.

SeaGal said:

It's not so much cooling efficiency but when air is at less pressure the insulation breakdown voltage becomes less.

So it's down to PCB design (gaps between tracks), coatings etc. i.e. insulation resistance

Click to expand...

From what I have read so far, it is about the insulation breakdown that happens at higher elevation with thinner air and lower pressure. You can get an arc fault on your internal components and maybe fry your system. I believe at 9,000 ft they need something like 14% more spacing than they do at 6,000 ft. Don't quote me as I'm not an expert in this but I've been reading other blog posts.