Will OutBack GVFX3648 trick an SMA grid tie inverter?

[Murby]

There is no need for the flexmax. You will be AC coupled with your SMA

though if you got two flexmax charge controllers you could dump the SMA, The outback will grid tie and feed extra power into the grid just like the SMA does with the batteries full most if the time.

And when the grid goes down for an extended period of time, will the Radian inverter trick my SMA Grid Tie inverter into making power?

[Murby]

If you are going to do this you have to use a switch that breaks both connections to the array and makes them to the new load. Both the SMA and the Flexmax want the panels to float. One version of the Morningstar 600V charge controller does this, so that's a good way to get it. The other way is a high voltage DPDT switch; these can be hard to find.

Will your array work with the 145V limit of the Flexmax?

My array is 28 panels of Solar World SW270. They put out about 36 volts at 8 amps or so.. So yes, with a bit of rewiring, it wouldn't be too difficult to change them from being wired in series for high voltage (400vdc @ 8amps), to wired in parallel for higher amperage (120vdc @64amps or more). I could probably put three in series for 120 volts and tie (parallel) several of the series together to kick the 8 amps up to something the flexmax's like better.

[bcroe]

My array is 28 panels of Solar World SW270. They put out about 36 volts at 8 amps or so.. So yes, with a bit of rewiring, it wouldn't be too difficult to change them from being wired in series for high voltage (400vdc @ 8amps), to wired in parallel for higher amperage (120vdc @64amps or more). I could probably put three in series for 120 volts and tie (parallel) several of the series together to kick the 8 amps up to something the flexmax's like better.

This I've got to see. Wonder how the fuses go into the circuit? Bruce Roe

[jflorey2]

My array is 28 panels of Solar World SW270. They put out about 36 volts at 8 amps or so.. So yes, with a bit of rewiring, it wouldn't be too difficult to change them from being wired in series for high voltage (400vdc @ 8amps), to wired in parallel for higher amperage (120vdc @64amps or more). I could probably put three in series for 120 volts and tie (parallel) several of the series together to kick the 8 amps up to something the flexmax's like better.

OK. That might not be as easy as it sounds at first blush.

First off, the existing wiring to the inverter probably isn't good for 64 amps, so unless you already have a segmenting disconnect near your inverter (which you probably don't) you're going to have to run a lot of new wiring to handle the current. And all the new runs have to be fused (or breakered) since you are going to have a massively parallel system.

Second, it's fairly dangerous to try to unplug 400V systems when they are energized, even at no load. It doesn't take much to turn a minor problem into a deadly one.

Third, if you are going to do this only when power goes out (which generally happens at the worst possible time) it's going to make things that much worse. Do you really want to be on the roof right after a storm, pulling apart wet, energized MC4 connectors?

If you are going to do this I'd strongly recommend choosing one voltage and sticking with it, so you don't need to do live wiring changes on the fly. Choose 150 volts and then do everything through one inverter (safest/simplest.) Or go with 600V and use the Morningstar with that built in DC switch. Or go 600 volts and wait for the Skybox, if it ever materializes.

[Murby]

this i've got to see. Wonder how the fuses go into the circuit? Bruce rpe

huh?

[max2k]

huh?

when combining more than 2 strings in parallel you need to fuse each one of them. In your case layout sounds like it would be 3x9 = 27 panels so you'd have 9 strings 3 panels each.

[Murby]

OK. That might not be as easy as it sounds at first blush.

First off, the existing wiring to the inverter probably isn't good for 64 amps, so unless you already have a segmenting disconnect near your inverter (which you probably don't) you're going to have to run a lot of new wiring to handle the current. And all the new runs have to be fused (or breakered) since you are going to have a massively parallel system.

That isn't actually a problem.. I have lots of din-rail mount circuit breakers, distribution blocks, etc.. I've wired more industrial control panels than I can remember.. pretty much all of it is 3phase 480 volt stuff which is rated 600 volts and pretty much all of it is also rated for high voltage DC, with the exception of relay coils of course.

Second, it's fairly dangerous to try to unplug 400V systems when they are energized, even at no load. It doesn't take much to turn a minor problem into a deadly one.

Thanks.. Working with that kind of equipment is second nature to me..

Third, if you are going to do this only when power goes out (which generally happens at the worst possible time) it's going to make things that much worse. Do you really want to be on the roof right after a storm, pulling apart wet, energized MC4 connectors?

If you are going to do this I'd strongly recommend choosing one voltage and sticking with it, so you don't need to do live wiring changes on the fly. Choose 150 volts and then do everything through one inverter (safest/simplest.) Or go with 600V and use the Morningstar with that built in DC switch. Or go 600 volts and wait for the Skybox, if it ever materializes.

No.. I'm not going to do this on a whim after a storm just because the power goes out for a few days. What I'm trying to set up is an insurance policy I hope I never have to use.. I just want the ability and the equipment required to set it up and/or make the necessary changes to make it work. I am fully aware that changing the system over to pure off grid would be a major job that would probably take days if not a few weeks to complete..
And I know what you're probably thinking now... the answer is yes, I'm going to invest close to $10,000 on equipment I may never need... But that's what insurance policies are all about..

Thank you for taking the time to give me advice...

[max2k]

OK. That might not be as easy as it sounds at first blush.

First off, the existing wiring to the inverter probably isn't good for 64 amps, so unless you already have a segmenting disconnect near your inverter (which you probably don't) you're going to have to run a lot of new wiring to handle the current. And all the new runs have to be fused (or breakered) since you are going to have a massively parallel system.

Second, it's fairly dangerous to try to unplug 400V systems when they are energized, even at no load. It doesn't take much to turn a minor problem into a deadly one.

Third, if you are going to do this only when power goes out (which generally happens at the worst possible time) it's going to make things that much worse. Do you really want to be on the roof right after a storm, pulling apart wet, energized MC4 connectors?

If you are going to do this I'd strongly recommend choosing one voltage and sticking with it, so you don't need to do live wiring changes on the fly. Choose 150 volts and then do everything through one inverter (safest/simplest.) Or go with 600V and use the Morningstar with that built in DC switch. Or go 600 volts and wait for the Skybox, if it ever materializes.

He has ground mounted array which he installed himself so I hope he'll manage. There were couple 'wild' panels in his shipment but that will remain mystery forever.
Disconnecting 400V DC should be done at no load due to DC arching. In that case it is also much less dangerous as even touching both MC4 ends after disconnecting wouldn't create path for the current to close the circuit. I wouldn't do it on purpose though- any leak current in the system would go through my body.

[max2k]

... pretty much all of it is 3phase 480 volt stuff which is rated 600 volts and pretty much all of it is also rated for high voltage DC ...

is it so? Please note DC breakers for the same voltage / amperage as their AC counterparts are completely different creatures as manufacturers need to go to great lengths to kill the arch which is created every time you turn them off, they have special anti- arch chambers etc. Basically it's not matter of listing it's matter of physics. Their prices also reflect that- 600V 20A DC breaker can cost couple hundred dollars.

[jflorey2]

That isn't actually a problem.. I have lots of din-rail mount circuit breakers, distribution blocks, etc.. I've wired more industrial control panels than I can remember.. pretty much all of it is 3phase 480 volt stuff which is rated 600 volts and pretty much all of it is also rated for high voltage DC, with the exception of relay coils of course.

OK. Be VERY sure of that. It's not easy to find 600VDC rated DIN-rail breakers, as I discovered when doing some EV work years ago.

No.. I'm not going to do this on a whim after a storm just because the power goes out for a few days. What I'm trying to set up is an insurance policy I hope I never have to use.. I just want the ability and the equipment required to set it up and/or make the necessary changes to make it work. I am fully aware that changing the system over to pure off grid would be a major job that would probably take days if not a few weeks to complete.

Oddly enough I am in much the same situation. Got a use Schneider 600V MPPT charge controller from a local Craigslist ad. It was cheap; I don't think the guy knew what it was. It's sitting in the storage unit now, but if the zombie apocalypse ever came it would be a way to bridge my solar (straight grid tie right now) and backup (battery based) systems. I have a strong feeling I will never need it, in which case I can probably sell it for more than I paid for it.

[Murby]

is it so? Please note DC breakers for the same voltage / amperage as their AC counterparts are completely different creatures as manufacturers need to go to great lengths to kill the arch which is created every time you turn them off, they have special anti- arch chambers etc. Basically it's not matter of listing it's matter of physics. Their prices also reflect that- 600V 20A DC breaker can cost couple hundred dollars.

I've honestly never bothered to pay attention to the DC ratings on my various industrial supplies.. I have a lot of Allen Bradley stuff.. Telemecanique, SquareD, etc.. I just know there's almost always a DC rating..
Again, I wouldn't use this stuff normally... only if it was a last resort knowing the grid wasn't coming back anytime soon..

[SWFLA]

is it so? Please note DC breakers for the same voltage / amperage as their AC counterparts are completely different creatures as manufacturers need to go to great lengths to kill the arch which is created every time you turn them off, they have special anti- arch chambers etc. Basically it's not matter of listing it's matter of physics. Their prices also reflect that- 600V 20A DC breaker can cost couple hundred dollars.

I think it's a race to see how expensive they can make this project

[Murby]

OK. Be VERY sure of that. It's not easy to find 600VDC rated DIN-rail breakers, as I discovered when doing some EV work years ago.

Oddly enough I am in much the same situation. Got a use Schneider 600V MPPT charge controller from a local Craigslist ad. It was cheap; I don't think the guy knew what it was. It's sitting in the storage unit now, but if the zombie apocalypse ever came it would be a way to bridge my solar (straight grid tie right now) and backup (battery based) systems. I have a strong feeling I will never need it, in which case I can probably sell it for more than I paid for it.

Great! I'm not the only wacko in the forum who wants an insurance policy! I feel much better now.. hehehe..

One suggestion though.. Get a metal 55 gallon drum with a removable lid.. the kind that has the clamp.... Line the inside of it with cardboard or other non-conductive insulator.. (I used 1/4 inch low density poly foam)... Then remove the rubber seal in the lid and replace it with a conductive EMI Shield like this stuff: eBay item number: 201236646772.. Put your emergency electronics inside the drum and seal it tight.
If you have any super sensitive stuff like a laptop, put it in a plastic bag first, then a mylar bag, seal it tight, then in the drum.

Now only will that setup stop moisture and bugs damaging things, it will protect from floods, water, physical damage, and in a worst case, an EMP..

[SWFLA]

DIN rails in something that has wheels. Sounds safe to me. That's funny. Maybe a locomotive.

[SunEagle]

DIN rails in something that has wheels. Sounds safe to me. That's funny. Maybe a locomotive.

Most control panels use terminal blocks and electronics that can be mounted via a DIN rail. It allows you more flexibility and ease to mount the items then attaching each to the back plain.