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

[GoldDigger]

Since all of the threads here on this sub-topic seem to be closed, I am starting up a new one.

For several (quite a few actually) months there has been discussion of the SMA 3000/4000/5000 TL-US grid tie inverter family with 12 amp (max!) 120 volt dedicated outlet for emergency power when the grid is down but the sun is shining. Without batteries.
It looks like to get the maximum of 1500 AC watts out will take something like 3000 DC watts available from the panels. If the insolation is not so good, you will get proportionally less, but at least good for cell phone charging.

Anyway, one of the members of another forum who is staff at the Solar Academy suggested watching the SMA Solar Academy site for more information, and I see that SMA has now opened a one hour webinar about that line of inverters and that feature. I have registered already at http://www.sma-america.com/en_US/sm...y_tl_us_series_eps_overview_live_webinar.html. At this time it looks like the first available date is 4/2.

Still no price list or other information on the SMA website, no ship dates, and the specifications are still labelled preliminary.

Just wanted to share the webinar information with those who might be interested and have not been actively following the product.

---GoldDigger

 

[GoldDigger]

Since all of the threads here on this sub-topic seem to be closed, I am starting up a new one.

For several (quite a few actually) months there has been discussion of the SMA 3000/4000/5000 TL-US grid tie inverter family with 12 amp (max!) 120 volt dedicated outlet for emergency power when the grid is down but the sun is shining. Without batteries.
It looks like to get the maximum of 1500 AC watts out will take something like 3000 DC watts available from the panels. If the insolation is not so good, you will get proportionally less, but at least good for cell phone charging.

Anyway, one of the members of another forum who is staff at the Solar Academy suggested watching the SMA Solar Academy site for more information, and I see that SMA has now opened a one hour webinar about that line of inverters and that feature. I have registered already at http://www.sma-america.com/en_US/sm...y_tl_us_series_eps_overview_live_webinar.html. At this time it looks like the first available date is 4/2.

Still no price list or other information on the SMA website, no ship dates, and the specifications are still labelled preliminary.

Just wanted to share the webinar information with those who might be interested and have not been actively following the product.

---GoldDigger

If anybody is interested in more information about the Emergency Power Supply (EPS) feature of the SMA Sunny Boy 3-5000 TL-US, you can ask here or PM me. The other news is that the units are actually shipping now to SMA Solar Pro Club distributors. (And no, I do not know anybody at any of them.)

 

[ggunn]

If anybody is interested in more information about the Emergency Power Supply (EPS) feature of the SMA Sunny Boy 3-5000 TL-US, you can ask here or PM me. The other news is that the units are actually shipping now to SMA Solar Pro Club distributors. (And no, I do not know anybody at any of them.)

Are they CEC listed yet?

 

[GoldDigger]

Are they CEC listed yet?

Unfortunately I did not get the answer to that. (I missed the early part of the webinar). The non-preliminary documentation should be up on their website soon and that should tell.

However, they do incorporate series-AFCI on the DC side! (UL-1699B)

The model number xxxxxUS leads me to believe that their first priority is the US-specific listings. Whether they consider California a critically large market segment, etc. was not discussed. I would imagine they will be shipping to some dealers in CA, so the question will surely come up.

 

[ggunn]

Unfortunately I did not get the answer to that. (I missed the early part of the webinar). The non-preliminary documentation should be up on their website soon and that should tell.

However, they do incorporate series-AFCI on the DC side! (UL-1699B)

The model number xxxxxUS leads me to believe that their first priority is the US-specific listings. Whether they consider California a critically large market segment, etc. was not discussed. I would imagine they will be shipping to some dealers in CA, so the question will surely come up.

As you may know, the CEC listing is not just important in California. Inclusion on the list is a requirement for equipment to be installed in many (most?) jurisdictions in the US in order for systems to qualify for incentive programs.

 

[GoldDigger]

As you may know, the CEC listing is not just important in California. Inclusion on the list is a requirement for equipment to be installed in many (most?) jurisdictions in the US in order for systems to qualify for incentive programs.

The technical specifications for these models is no longer listed as "Preliminary" on the SMA website (http://www.sma-america.com/en_US/pr.../sunny-boy-3000tl-us-4000tl-us-5000tl-us.html) and the various UL, IEEE and Canadian certifications are listed. No mention of CEC, but the efficiency figures graphed on the same page indicate that it should have no problem meeting the requirements once all of the paperwork has been properly pushed.
Note that the lowest voltage for operation is shown as 175 volts. Actually it will start at 175 volts but stay running as low as 125 volts. I expect the efficiency tobe lower below 175 volts, but that would only come into play with multiple panel shading on a string which was low in voltage to begin with.

 

[Garrison]

This seems like it will be a great little inverter, if it's ever released (SB240 has been with Pro Club members for some time now), but I have some reservations about the 15A EPS.

What happens when a customer plugs in their fridge and it's pulling 6A, then a cloud passes by and the inverter can only output 2A? Some appliances may be able to handle this, but some may not. Maybe installing a UPS or similar could help prevent issues caused by our variable energy source? Do others see this as an issue? Thoughts on how to prevent damage?

 

[ggunn]

The technical specifications for these models is no longer listed as "Preliminary" on the SMA website (http://www.sma-america.com/en_US/pr.../sunny-boy-3000tl-us-4000tl-us-5000tl-us.html) and the various UL, IEEE and Canadian certifications are listed. No mention of CEC, but the efficiency figures graphed on the same page indicate that it should have no problem meeting the requirements once all of the paperwork has been properly pushed.
Note that the lowest voltage for operation is shown as 175 volts. Actually it will start at 175 volts but stay running as low as 125 volts. I expect the efficiency tobe lower below 175 volts, but that would only come into play with multiple panel shading on a string which was low in voltage to begin with.

That is all well and good, but until they are on the CEC list, I cannot install them here.

 

[jaggedben]

That is all well and good, but until they are on the CEC list, I cannot install them here.

It's not like these are quite available yet. I have a feeling you'll see the CEC listing by the time they actually are.

 

[SolarPro]

What happens when a customer plugs in their fridge and it's pulling 6A, then a cloud passes by and the inverter can only output 2A? Some appliances may be able to handle this, but some may not.

Don't plug in the fridge. This is a 15 A convenience outlet, not a critical load panel. You can't keep food cool overnight with it. It's not going to handle motor surges. You can charge cell phones and laptop computers while you cook up all of the perishable items in your fridge.

 

[jaggedben]

Most newer fridges only pull an amp or two, so that may not be too out of bounds. I'd be more worried about people trying to use a microwave.

With that said, I agree that it's not a critical load panel. Hopefully this feature is designed so it shuts down cleanly if there is any overdraw on the power, and delays long enough before starting up again that appliances can't experience high frequency on/off events. I doubt most appliances would be easily damaged (including fridges), but enough people will try to use it for inappropriate things that it'd better be fairly robust.

 

[Garrison]

Don't plug in the fridge. This is a 15 A convenience outlet, not a critical load panel. You can't keep food cool overnight with it. It's not going to handle motor surges. You can charge cell phones and laptop computers while you cook up all of the perishable items in your fridge.

We may understand that, and will try to educate the initial purchaser, but I agree with Jagged that customers are going to plug all types of things into this outlet. I just see complaints when it doesn't power their electric heater, or results in damage to their 70" flat screen. A low power disconnect (and OCPD) or similar would be a good idea...hopefully not just a waiver of liability.

 

[ggunn]

We may understand that, and will try to educate the initial purchaser, but I agree with Jagged that customers are going to plug all types of things into this outlet. I just see complaints when it doesn't power their electric heater, or results in damage to their 70" flat screen. A low power disconnect (and OCPD) or similar would be a good idea...hopefully not just a waiver of liability.

That's good question. What happens if you try to pull more current than is available?

 

[GoldDigger]

That's good question. What happens if you try to pull more current than is available?

Very simple according to the SMA instructor: When the load goes above either the 12 amp absolute max or the maximum amount the PV can power at the moment the EPS will shut down. Cleanly and positively. It will then recheck the load at 20 second intervals and will power back up if the load at that moment is within the available power at that moment. The way it checks for load is to apply voltage briefly, so there may be a lower than standard voltage applied to an overload for a short time. I think this is similar to the economizer mode of an off-grid inverter or a generator. There was no information on whether there is some number of cycles worth of energy storage (ultra-capacitor?) in the SunnyBoy for use by the EPS or not.
I would not expect electronics to be damaged by this, but something that requires a clean power-on reset may get confused until it finally stays on.

Sensitive equipment or motor loads would benefit from a load-sharing UPS, but it is not clear what application would make that cost worthwhile for the limited power that the EPS can supply.

 

[SolarPro]

That's an interesting question. Obviously, the EPS requires some additional software, but I wonder what the hardware implications are. Did SMA have to add capacitors to their basic inverter design in order to add the EPS, or use some sort of advanced capacitors? What was the main technological hurdle?

I remember hearing about inverters in Japan that had this EPS capability way back in the early-2000s. If the EPS was technically possible a decade ago, why did it take a decade for a company to introduce this commercially in the US? (Liability for fried electronics could be high on that list.) This is basically a product feature that customers with utility interactive PV systems have always wanted.

Whatever the reasons for the long development schedule, I suspect that SMA has worked the bugs out of the EPS system. Yes, they have a history of announcing some solutions well before they are ready for market. But they do a really good job of releasing robust products that work as advertised and have all of the required certifications. (This will be on the CEC list before it ships.)

 

[GoldDigger]

That's an interesting question. Obviously, the EPS requires some additional software, but I wonder what the hardware implications are. Did SMA have to add capacitors to their basic inverter design in order to add the EPS, or use some sort of advanced capacitors? What was the main technological hurdle?

I remember hearing about inverters in Japan that had this EPS capability way back in the early-2000s. If the EPS was technically possible a decade ago, why did it take a decade for a company to introduce this commercially in the US? (Liability for fried electronics could be high on that list.) This is basically a product feature that customers with utility interactive PV systems have always wanted.

Whatever the reasons for the long development schedule, I suspect that SMA has worked the bugs out of the EPS system. Yes, they have a history of announcing some solutions well before they are ready for market. But they do a really good job of releasing robust products that work as advertised and have all of the required certifications. (This will be on the CEC list before it ships.)

One indication that there must be additional hardware inside is that the output in GTI mode is 240 volts, split phase, and the only reason that there is a neutral present is so that the UL-required check for voltage balance can be made as part of the grid validation.
But the EPS output is 120 volt only. There also has to be a source of the 60Hz reference frequency (although that could just be derived from the system clock frequency of the processor, or some other source which was already present.)
Since these are transformerless inverters, there has to be some sort of charge pump circuitry that allows for both + and - output with respect to ground from a single-sided PV input, even in normal GTI mode. But unless they limit the total current (12 amps RMS) to only half of the panel current, they will have a problem delivering the peak current of the output sine wave. I am pretty sure that there is at least a few cycles worth of storage, some of which may have already been present in the GTI for efficiency and input current smoothing. The energy storage could well be in the intermediate step of the DC conversion rather than at the actual input.

 

[jaggedben]

Since these are transformerless inverters, there has to be some sort of charge pump circuitry that allows for both + and - output with respect to ground from a single-sided PV input, ...

Hmmm... why "with respect to ground?" Also prompts the question: Will the outlet be two prong or three prong?

 

[GoldDigger]

Hmmm... why "with respect to ground?" Also prompts the question: Will the outlet be two prong or three prong?

Definitely three. Since it will not be connected to your house wiring, it is not clear what the bonding will be, but probably still derived from the grid-connected side. Hmm. What happens if you disconnect all grid side wires including the neutral?

 

[Garrison]

Looks like they made it to the CEC list. Hopefully distributor's price lists will follow shortly.

http://www.gosolarcalifornia.org/equipment/inverters

 

[GoldDigger]

Looks like they made it to the CEC list. Hopefully distributor's price lists will follow shortly.

http://www.gosolarcalifornia.org/equipment/inverters

Possibly CEC does not publish the listing until the model is shipping in production, indicating that the design is finalized.