SMA Grid Tie inverters with battery-less emergency power feature are getting closer.

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Secure Power Supply

Secure Power Supply

Hello everyone, Greg Smith from SMA America here. It looks like GoldDigger has a good handle on our new family of TL inverters but I thought I would chime in with a few things.

The inverters did make it on the April release of the CEC list on Monday and a limited shipment was doled out to our Sunny Pro Club members and then off to our distributors. Each month we will be getting more and more of them and expect full production at our Denver facility some time this year.

We changed the name of the power supply on this inverter to Secure Power Supply (SPS) since we later found out that NEC 700 has strict verbiage on what constitutes an "emergency power supply" and since our solution does not require batteries, we decided to change the name. Here is a link to a tech note on our website that discusses the NEC implications of using this inverter and this new feature: http://files.sma.de/dl/18726/EPSCompl-US-TB-en-10.pdf

While the temptation is just too much to resist, our installation manual recommends that, "... you should not supply loads with the [secure] power operation that rely on a stable voltage supply." If you are concerned about a load, like a fridge or grandma's iron lung, then don't plug it into the socket being fed by this inverter. This is a resource for a small amount of power to be used when the grid goes out and you need to keep small loads on. Here is the technical description of the SPS: http://files.sma.de/dl/18726/EPS-US-TB-en-10.pdf

If you want backup power for larger loads then I would recommend clicking this link :D http://www.sma-america.com/en_US/products/off-grid-inverters/sunny-island-4548-us-6048-us.html

Lastly, here is a video of the SPS in action: http://www.smainverted.com/2013/02/21/groundbreaking-new-feature-on-sunny-boy-tl-us-emergency-power-when-the-grid-fails/

We have frequent webinars on our products and this one is getting a lot of attention. This SPS is just one of the many features of this game-changing inverter. Drop on in or send us an email if you have any questions. I've already been in contact with several AHJ's and utilities about this product and it is getting favorable feedback.

Sunny regards,

Greg Smith
SMA America, Senior Technical Training Specialist
 
Couple other goodies in this inverter:
1. I recall it being transformerless ( i think it safer, as you can float array)
2. and dual MPPT.
 
Zee said:
Couple other goodies in this inverter:
1. I recall it being transformerless ( i think it safer, as you can float array)
2. and dual MPPT.
Click to expand...

It also has a DC-side AFCI as currently required by UL. Won't that be fun?
For those who have severe shading issues, it will start as low as 175 volts DC but will hold on as low as 125 DC once started.
That only comes into play if your series string is much higher in voltage but is half or more shaded at some times during the day, reducing voltage while still allowing full current via bypass diodes.
 
Putting a UPS in series might be a better application of this feature. I'm not sure how "secure" a power supply is if it requires that the sun is shining. Which it isn't at least half the time. We've had miserable weather here of late and that included days on end when I couldn't have made more than 4 or 5 amps AC (120 volt) off 5kW DC.

If you want a reliable 15 amp convenience outlet, there's still no substitute for batteries.
 
Considering that all grid tied inverters will produce 0W when the grid is down (and the sun is shining) I'd say that getting up to 1500W is pretty secure!

When presented with the option of spending $10k+ for a battery bank to charge cell phones, radios, small refrigerators, or other small loads during an emergency, homeowners will flock to this much more economical solution.
 
For sure. It's really more of an intermittent convenience receptacle than an emergency power supply. But it's a significant product differentiator.

In the event of an outage, the potential to have a little power for 12 hours a day is considerably better than having no power. Even if it costs a little more, I suspect that customers will gladly pay he difference. With so much downward price pressure in the market, SMA is smart to introduce a product they can potentially sell at a premium.
 
SolarPro said:
For sure. It's really more of an intermittent convenience receptacle than an emergency power supply. But it's a significant product differentiator.
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A question which I raised, with an "I guess we need to look into that..." response from the instructor, was whether the convenience outlet would require labeling that identifies it as powered by an alternate source and therefore potentially live when POCO was disconnected.
The outlet can be placed either indoors or outdoors (with appropriate enclosure.)
 
GoldDigger said:
A question which I raised, with an "I guess we need to look into that..." response from the instructor, was whether the convenience outlet would require labeling that identifies it as powered by an alternate source and therefore potentially live when POCO was disconnected.
The outlet can be placed either indoors or outdoors (with appropriate enclosure.)
Click to expand...
I thought the outlet was mounted on the bottom of the inverter.
 
ggunn said:
I thought the outlet was mounted on the bottom of the inverter.
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Nope. There are terminals inside the inverter for attachment of an external outlet (three wire) and external control switch (two wire?). It is not clear whether the control switch is low voltage, etc. but it needs to be wired as full line voltage since it will be in the same raceway.
While the switch is open, the inverter will not enter the optional standby power mode.
 
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tallgirl said:
Putting a UPS in series might be a better application of this feature. I'm not sure how "secure" a power supply is if it requires that the sun is shining. Which it isn't at least half the time. We've had miserable weather here of late and that included days on end when I couldn't have made more than 4 or 5 amps AC (120 volt) off 5kW DC.

If you want a reliable 15 amp convenience outlet, there's still no substitute for batteries.
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Or a 1,000 megawatt coal-fired power station. ;)
 
jaggedben said:
Talk about not getting it. This feature is precisely for the situation where the coal-fired power station is not available.
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Talk about not having a sense of humor. Tallgirl specifically said "a reliable 15 amp convenience outlet" (emphasis mine). In no way can solar be considered reliable on a local scale (one house) and almost certainly not on a regional scale. I merely closed the circle from solar-only --> solar-with-battery --> grid-based power.

Not that I don't think solar has its place, but to paraphrase Harry Callahan, "A power source has got to know its limitations."
 
When I have customers worried about doomsday scenarios, I usually recommend a sophisticated CWFI emergency backup system.
Candles
Wine
Flashlight
Ice (Tons of ice in the freezer for cold mass).
 
gadfly56 said:
Tallgirl specifically said "a reliable 15 amp convenience outlet" (emphasis mine).
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Yes and she said the only way for that is batteries. Which I agree with. Grid+UPS is more reliable than grid without UPS. Grid+UPS+Solar is arguably the most reliable.

You were trying to make a joke? :blink: Hmm. You know how they say "It's funny because it's true"? Well, the contrapositive applies as well sometimes.

In no way can solar be considered reliable on a local scale (one house) and almost certainly not on a regional scale.
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Solar can certainly be reliable on a one house scale. It is just (usually) more expensive than the grid, that's all.

Solar on a regional scale can be very reliable. Of course it requires ramping when the sun rises and sets. Nothing by itself is reliable on a regional scale, except maybe gas. Coal needs help with load-following and balancing, too.
 
GoldDigger said:
A question which I raised, with an "I guess we need to look into that..." response from the instructor, was whether the convenience outlet would require labeling that identifies it as powered by an alternate source and therefore potentially live when POCO was disconnected.
The outlet can be placed either indoors or outdoors (with appropriate enclosure.)
Click to expand...

I remember this question and it is always a good sign when people are digging into the technology. As an inverter manufacturer we release the technology and then let the market figure out how to implement it. Using Code as the foundation of our industry's safety standards, I found a few articles related to labeling/marking- none of which apply to this inverter and its associated receptacle ;)

690.53 DC PV Power source
690.55 PV Systems Employing Energy Storage
690.56A Facilities with stand alone systems
690.56B Facilities with utility services and PV

These are all marking requirements that will be used anyway, however there is nothing that I have found in the Code that addresses a PV system without batteries that is supplying a convenience receptacle. If someone can find that reference I'll buy you a few beers at the next SMA Solar Academy event :D

We will be providing labels for the inverter and the outlet that give instructions on how to activate the power and how to deactivate it when the grid comes back. Perhaps another sticker would be prudent that identifies the outlet as a possible energized source during grid outtages, similar to a battery backup marking requirement.

Greg Smith
SMA America
Senior Technical Trainer
 
Q-5 Hunter said:
We will be providing labels for the inverter and the outlet that give instructions on how to activate the power and how to deactivate it when the grid comes back. Perhaps another sticker would be prudent that identifies the outlet as a possible energized source during grid outtages, similar to a battery backup marking requirement.

Greg Smith
SMA America
Senior Technical Trainer
Click to expand...

Thanks for responding Greg,

My second concern is identifying that the outlet may be hot when grid is up but somebody has disconnected at the main, expecting to have killed all power on site. The concern then is not nearly as great, because unless the switch is flipped the outlet will still not be hot. But that brings up what sort of voltage is present on the switch leads themselves. I would guess a low-level control signal or relay coil circuit, but that is not specified.
 
You are correct about the relay. The terminals inside the inverter will not allow voltage to the outlet until the switch on the outlet is turned on. This prevents any stray voltages outside the inverter to exist if the inverter does not sense grid voltage on L1-L2 and the switch on the outlet is turned off.

I am going to try and attach part of our training slides that explains the logic involved with the SPS and grid interaction. We discuss this in our webinars which can be found on the Solar Academy page of SMA America's site. I think it will only stay on the forums for an hour if there is no activity detected on download. If it isn't available, the whitepaper has a decent description: http://files.sma.de/dl/18726/EPSCompl-US-TB-en-10.pdf

We appreciate the feedback and want to make the integration of this groundbreaking feature as smooth as possible. View attachment Secure Power Supply_1.pdf
 
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