Flip Switch on grid tie system during outage.

[iandowny]

Here is a question that was probably answered somewhere but, my search didn't turn anything up.

The reason I was told that we cannot have power during outage in a grid tie system is to protect the linemen working on the line(s).

If that is the only reason, what is to say there cannot be a flip switch which makes the grid tie system NOT connected to the grid, but, still power our home during sunny and hot afternoons and evenings?

[iandowny]

but, my search didn't turn anything up.

Looked closely and I think the answer would be a definite NO with a modest budget. Thank you all.

[DanS26]

Research some of the new SMA grid tie inverters. You might be surprised.

[inetdog]

Here is a question that was probably answered somewhere but, my search didn't turn anything up.

The reason I was told that we cannot have power during outage in a grid tie system is to protect the linemen working on the line(s).

If that is the only reason, what is to say there cannot be a flip switch which makes the grid tie system NOT connected to the grid, but, still power our home during sunny and hot afternoons and evenings?

The other reason that you cannot do it with a standard GTI is that different circuitry is required to operate as a standalone inverter, and its power output is strictly limited by the power the panels are producing at that exact moment.
As mentions, the SMA 3,4,5000 TL-US do have this capability, but only to the extent of 120 volts at up to 12A maximum. Less than 12A in less than full sun.

[BrandonWWS]

Research some of the new SMA grid tie inverters. You might be surprised.

Yea, the SMA TL is COOL! It did not cost my last client much more and he has 2 backup plugs that connect to communications styled UPS units on a network rack.
X42 Suniva 255 panels,X2 5000-TL-US,IronRidge racks and all the trimmings installed near Austin Tx
Installed cost was around $3, before rebate from uncle sam

We put 2 of the 5kTL's and hid all the wiring behind the wall so all you see is the inverters on the wall but no conduit and managements.. I would hook up another one, they are easy to do. The TL series install was my first experience with SMA and I was pleased with the results thus far.

It is totally the way to go if you just want "some" backup on your system... The UPS units run 110/220 so a well pump in theory could be run on the backup circuit but you might have to add a second small UPS like one for your computer behind the large networking 110/220v UPS because some of the large ones will draw on charging, more than the backup circuit handles... So picture like a 5000-TL flip switch backup circuit hooked up to your computers UPS then that UPS is hooked up to your BIG UPS that runs the backup and now, NIGHTTIME backup loads...

I would hook another one up for sure. Very much an easy and cool hybrid type solution.

[DanS26]

Yea, the SMA TL is COOL! It did not cost my last client much more and he has 2 backup plugs that connect to communications styled UPS units on a network rack.
X42 Suniva 255 panels,X2 5000-TL-US,IronRidge racks and all the trimmings installed near Austin Tx
Installed cost was around $3, before rebate from uncle sam

We put 2 of the 5kTL's and hid all the wiring behind the wall so all you see is the inverters on the wall but no conduit and managements.. I would hook up another one, they are easy to do. The TL series install was my first experience with SMA and I was pleased with the results thus far.

It is totally the way to go if you just want "some" backup on your system... The UPS units run 110/220 so a well pump in theory could be run on the backup circuit but you might have to add a second small UPS like one for your computer behind the large networking 110/220v UPS because some of the large ones will draw on charging, more than the backup circuit handles... So picture like a 5000-TL flip switch backup circuit hooked up to your computers UPS then that UPS is hooked up to your BIG UPS that runs the backup and now, NIGHTTIME backup loads...

I would hook another one up for sure. Very much an easy and cool hybrid type solution.

That's an interesting concept......daisy chaining UPS devices. Is that possible and if so how many could be connected in series? What would the power curve look like?

[russ]

That's an interesting concept......daisy chaining UPS devices. Is that possible and if so how many could be connected in series? What would the power curve look like?

Before we get too carried away with the BS it would be better to get Sunking's input.

[Sunking]

That's an interesting concept......daisy chaining UPS devices. Is that possible and if so how many could be connected in series?

No. With UPS they can be in Parallel Redundant where you have two or more in parallel so that if one fails, the other is standing by to take over., but only one UPS is actually on line while the others are just setting there. Pretty common in data centers where outages are not acceptable and cost is no real concern.

The other method is called Isolated Redundant or Exclusive OR, but I have never seen or heard of one ever being used.

[Mike90250]

That's an interesting concept......daisy chaining UPS devices. Is that possible and if so how many could be connected in series? What would the power curve look like?

BAD ! Each UPS charger has to roughly have a 20% loss. better to have a decent automated charger and a dedicated inverter to power your critical loads, and use any solar, to keep the battery charged. I think the SMA needs you to manually flip a switch to enable the special outlet and reset it if the sun blinks. It's not totally automatic.

[BrandonWWS]

BAD ! Each UPS charger has to roughly have a 20% loss. better to have a decent automated charger and a dedicated inverter to power your critical loads, and use any solar, to keep the battery charged. I think the SMA needs you to manually flip a switch to enable the special outlet and reset it if the sun blinks. It's not totally automatic.

Yep, the SMA TL backup switch is fully manual.. I think in a year or so, this will be an automatic feature either through SMA or the next outfit to make up their own "emergency backup". I hope

Yea the loss is probably bad with UPS's but it only cost like 500 bucks in parts with the network rack included! Good ole surplus telecom vendors all the way. I never thought that after leaving the networking and RF world that I would be calling old vendors looking for RE gear.

Installed a couple of micro-inverter systems that hook up to a Magnum inverter for grid outage sine wave and power but needed a few thousand for the the batteries of course for night time loads... Just the inverter and power center was around 2k.. There are a few ways to do backup on grid-tie but the one I made on the fly for the dude was all that was available on his shoe string budget. Pretty sure but let me know if wrong Mike90250 but some kind of charger and the inverter would run way over the budget this client had. What about batteries for the charger?

BreeZee

[inetdog]

Yep, the SMA TL backup switch is fully manual.. I think in a year or so, this will be an automatic feature either through SMA or the next outfit to make up their own "emergency backup". I hope

Although the wiring instructions from SMA describe connecting to a manual switch (standard, possibly weatherproof snap-switch), the input to the TL is just a contact closure. The switch is NOT part of the pre-connected inverter assembly.
Although it may not be UL approved for use in any other way than manual, it would be possible to "flip the switch" using a relay controlled by something else. Not that I would suggest doing that, of course.
The unreliability of the output even when on is such that I would not really expect much from automatic operation anyway, at least not in terms of critical loads.

The worst part, as I see it, is that when the backup power shuts down because of a cloud going by you will have to toggle the switch to get it back on.