Why no 240V Split-Phase Inverters with >600 Voc MPPT?

[Wet1]

In the US we consider HV max PV input to be 450V-500V Voc, with a couple of very rare exceptions coming in at 600V Voc max. Overseas, I am to understand there are inverters that handle 900V, possibly even higher, and it's not totally uncommon to see these significantly higher voltages. Obviously this would offer some significant advantages, so why don't we see >600V in the US?

I understand HV represents some potential safety concerns, so maybe that's the sole reason we don't see >600V inverters here? Although, 450V-600V with a little current is already high enough to be a safety threat for someone stupid enough to lick the exposed wires, so what's the concern with going up to say 900V? Especially if it's already being done elsewhere without issue? Is there a technical reason I'm missing that has to do with implementing it with split-phase? Is it lack of demand from NA installers who have traditionally worked with LV and are just slow to move to the potential benefits of even higher voltages?

 

[4thHorseman]

I'm literally guessing right now so expect this answer to be wrong but I'm assuming it has something to do with it being 240v there instead of our 120/130v. It's just double for that reason over there. Which means their infrastructure for anything is built for it.

 

[michael d]

Sandi makes a high voltage split phase inverter and ipanda makes a high voltage MPPT solar charge controller..... I think in the USA it is about safety of the high voltage equipment and the fact that the mass produced low voltage equipment is making the vendors tons of money..

the high voltage was touched on in some Jack Rickard YouTube videos Of (evtv motor werks) and now in May/June 2022 by YouTube videos of Mike G...

high voltage DC adds simplicity yet more danger at the same time....IMO

???

 

[timselectric]

It's just a matter of what the market wants.
Not very long ago, 250v was considered crazy high.
A lot of it depends on what the max voltage rating is for the solar panels. A lot of the ones being used currently, are rated for 600v max.

 

[Shimmy]

It is the NEC. They only opened up 600-1,000V for PV fairly recently-- less than 5 years IIRC. I don't remember the specific things that were impacted, but string voltage was a challenge for sure.

[edit] But, for residential (in the US), there is absolutely no place for 1,000VDC IMO. It is inappropriate for dwelling structure wiring. You could make an argument for ground-mount with string inverters outside... but I would still disagree.

 

[Rednecktek]

Also note that unless you're buying specialty wire, pretty much any wire you can get is only rated for 600v on the insulation. Even the marine grade wire often times may be able to carry higher amps or work at higher temps, but it's still only rated for 600v.

 

[OzSolar]

600V is the cut off for NEC for residential. In the US 240 split phase is most common voltage.

Plenty of 3 phase inverters with with 1000v upper limits are available in the US. SMA's Core is one example. But when you do that you have to step up to 2KV rated wire.

 

[timselectric]

600v is more than enough for any standard residential system.

 

[John Frum]

600v is more than enough for any standard residential system.

You may be right but, that kind of statement has forever to become wrong.
Just ask Bill Gates.

 

[Shimmy]

640V should be enough for anyone!

There are a few simple products that make more than 600V unnecessary unless you are talking about a system over 60kW. A combiner box seems to be a last resort for many people, but it is a nice, simple solution. The Y cables with inline fuses are also great for small residential systems.

 

[timselectric]

A combiner box is only useful if you need to run larger wires. Higher voltage avoids this necessity. Higher voltage makes the system easier and less expensive.

 

[timselectric]

You may be right but, that kind of statement has forever to become wrong.
Just ask Bill Gates.

Ultimately true. But for this moment in time, I'll stand by it.

 

[timselectric]

Wouldn't it be nice if you could run 50kw of solar on a single piece of CAT6. lol

 

[Rednecktek]

Wouldn't it be nice if you could run 50kw of solar on a single piece of CAT6. lol

Back in "The Day" people were talking about running their appliances and vacuum cleaners off of USB. Electricity doesn't work that way.

 

[timselectric]

Back in "The Day" people were talking about running their appliances and vacuum cleaners off of USB. Electricity doesn't work that way.

Maybe, if each appliance had a built-in battery. You could probably vacuum, once a week. And, use the oven every Thanksgiving.

 

[Shimmy]

A combiner box is only useful if you need to run larger wires. Higher voltage avoids this necessity. Higher voltage makes the system easier and less expensive.

... and just a little more dangerous. Bumping up a wire gauge (or two) is a better investment IMO. 600V is quite substantial, a far reach from limiting to 150VDC.

 

[timselectric]

High amperage is a lot more dangerous than High voltage. Once you exceed 80v, it's all deadly.

 

[Shimmy]

High amperage is a lot more dangerous than High voltage. Once you exceed 80v, it's all deadly.

Respectfully disagree, at least when you are talking about the difference between ~400V and ~900V with people whose experience is with ~120VAC.

Finding proper, safe protection equipment is hard and more specialized when you get into higher voltages. Using the wrong equipment has much higher risk in these scenarios.

 

[Rednecktek]

Respectfully disagree, at least when you are talking about the difference between ~400V and ~900V with people whose experience is with ~120VAC.

I have to say from personal experience that I created more new swear words after getting hit with 600v than I ever did getting hit with 440v

 

[timselectric]

I'm in no way saying that unqualified people should be doing any electrical work. Especially when the dangers are increased. That's why it's important to gain all necessary knowledge before starting any project. Electrical or not.