Enphase storage & grid protection

[Engineer]

I've got an Enphase inverter system and am looking at their new battery system, called Enphase Storage. Clearly they intend this system to be used for optimizing solar usage, from their data sheet


Services Maximizing self-consumption of solar, time-of-use bill management, power export limiting (with Enphase microinverters)


I'll get a few batteries just to play with it and optimize my near-peak usage in the early evening, the cost appears to be about $800/USD per battery (1.2kWh) launching later this year. Installation cost appears to be lowered as Enphase cabling isn't needed, just normal AC wiring and some brackets.

My question is what would be needed to turn this system from a grid tied to a hybrid? Specifically one that when the grid goes down it cuts itself off from the main grid creating a house micro-grid. Simple minded take is that it needs a mains breaker that cuts out when the system goes down, and a new internal frequency generator for the inverters to synchronize to. Thoughts?

Here are some links to enjoy

Why we love Enphase’s AC Battery solution
Enphase makes global battery storage launch in Australia, storage trial with SA network

[SunEagle]

Your post got tagged because of too many links attached to it. They are all ok by me so I approved your post.

Oh. I also deleted the other two post with the same information. We try not to duplicate the same post because of confusion

[Engineer]

Ah, unfortunately it appeared like it just swallowed the post which is why I resubmitted, and unfortunately had to rewrite it the first time! Anyhow, explained, thanks.

[ncs55]

I've got an Enphase inverter system and am looking at their new battery system, called Enphase Storage. Clearly they intend this system to be used for optimizing solar usage, from their data sheet


Services Maximizing self-consumption of solar, time-of-use bill management, power export limiting (with Enphase microinverters)


I'll get a few batteries just to play with it and optimize my near-peak usage in the early evening, the cost appears to be about $800/USD per battery (1.2kWh) launching later this year. Installation cost appears to be lowered as Enphase cabling isn't needed, just normal AC wiring and some brackets.

My question is what would be needed to turn this system from a grid tied to a hybrid? Specifically one that when the grid goes down it cuts itself off from the main grid creating a house micro-grid. Simple minded take is that it needs a mains breaker that cuts out when the system goes down, and a new internal frequency generator for the inverters to synchronize to. Thoughts?

Here are some links to enjoy

Why we love Enphase’s AC Battery solution
Enphase makes global battery storage launch in Australia, storage trial with SA network

Personally, I am not sold on the Enphase solution yet. It is still new and not proven in the field as of yet. Just my opinion. For Going hybrid I would consider first what are your exact concerns and needs, doing your homework on the products available and reliability factor, what their features are and how to design and integrate them into your existing system affordably. Personally, I would consider adding something like The Conext SW or XW inverter with a solid battery bank that is matched for your load profile when the grid is down. The SW is a newer inverter line that is smaller and more affordable than the XW units. I am not sure if the Enphase system can be AC coupled with either, but I know that a Sunny Boy can be AC coupled with the XW. Also when you are considering making your system into something that it was not really designed for. You will need some type of transfer switch to shift the power away from the grid and to your critical load center when the grid goes down. Transfer switches are pretty costly. XW's have internal transfer switches and I think the SW's do as well. If you are serious about going hybrid it will cost a little bit of money to achieve a robust and reliable system and may involve abandoning enphase all together to achieve what you want. We are having great success with the XW inverters and the 600V charge controllers and or AC coupling with SMA's. It is a costly system but works flawlessly and can accept generator input which we think is necessary to have as a backup source. On that note the SW can accept a 120V generator input and give you a 240v output which can come in handy even if you do not normally need it.

http://solar.schneider-electric.com/solution/residential-grid-tie-with-backup-power/?mc_cid=a56e5ba91b&mc_eid=e836575e99

https://www.youtube.com/watch?v=DXfMFV7UVrc&mc_cid=a56e5ba91b&mc_eid=e836575e99

[Engineer]

Here's an article by an Enphase guy on the batteries. Pretty good I think, he's not trying to pitch them it seems but being honest by saying that only well heeled early adopters will get into them now. Some exceptions in different markets, Germany and Australia it makes more sense. Anyhow it seems they've got a longer view which is this will be cheaper and make more sense in the next few years, so they're positioning themselves now.

A Battery Is Just A Battery and Other Myths About Energy Storage

[ButchDeal]

I've got an Enphase inverter system and am looking at their new battery system, called https://enphase.com/en-us/products-and-services/storage/our-system"]Enphase Storage[/URL]. Clearly they intend this system to be used for optimizing solar usage, from their https://enphase.com/sites/default/files/ACBattery-DS-EN-US.pdf"]data sheet[/URL]


Services Maximizing self-consumption of solar, time-of-use bill management, power export limiting (with Enphase microinverters)


I'll get a few batteries just to play with it and optimize my near-peak usage in the early evening, the cost appears to be about $800/USD per battery (1.2kWh) launching later this year. Installation cost appears to be lowered as Enphase cabling isn't needed, just normal AC wiring and some brackets.

My question is what would be needed to turn this system from a grid tied to a hybrid? Specifically one that when the grid goes down it cuts itself off from the main grid creating a house micro-grid. Simple minded take is that it needs a mains breaker that cuts out when the system goes down, and a new internal frequency generator for the inverters to synchronize to. Thoughts?

Here are some links to enjoy

http://roofjuice.com.au/why-we-love-enphases-ac-battery-solution/"]Why we love Enphase’s AC Battery solution[/URL]
http://onestepoffthegrid.com.au/enphase-makes-global-battery-storage-launch-in-australia-storage-trial-with-sa-network/"]Enphase makes global battery storage launch in Australia, storage trial with SA network[/URL]

The enphase battery will not provide backup capability.
The only way to get bimodal backup, out of your micros is with an AC coupled system using Outback power, xantrex, or SMA etc...

[ButchDeal]

Except the enphase battery is not a true bimodal system. It does not support backup capabilities, so grid down, enphase down.

[Engineer]

Yeah that's my question I asked above, what would be needed to make it off grid? Writing from Enphase seems to indicate it's not a big deal, obviously you need some extra gear.

[ButchDeal]

What would be needed to make the enphase seem operate when the grid is down?
It would take a system by another manufacturer that can do it. Enphase can not.
Enphase indicates it isn't that big of a deal because they can't do it.

[DanKegel]

What's needed? Some upgrade that would be as expensive as starting over

Best wait for equipment that promises hybrid operation from the start ( unless you want to engineer a system yourself ).

[ButchDeal]

You need an inverter charger that is designed and programmed to control the enphase inverters to make that work. Try it with a cheap inverter and get a nice warm fire....

[Engineer]

I believe there is at least one that integrates closely with Enphase, Magnum maybe.At any rate Enphase has a white paper on using their inverters with hybrid or off grid, and with the new batteries so they support it, I'm just trying to figure out how.

[ButchDeal]

Yes outback and xantrex will work but not the enphase battery. Their white paper is about AC coupling with other inverters which have their own batteries not going in their battery though. The enphase battery does not support backup.

[DanKegel]

Let us know what you find out!

[Engineer]

Here's the whitepaper
AC Coupling of Enphase Microinverters to Battery Based System

Enphase Microinverters work with a number of battery-based inverter manufacturers and component manufacturers, including Magnum Energy, Outback Power Systems, MidNite Solar, SMA, and Schneider Electric. You can find many other documents, application notes, and schematics on AC Coupling at the following websites.

Magnum Energy

http://www.magnumenergy.com/Documents/DocsFront.htm

Outback Power Systems

http://www.outbackpower.com/index.php/applications/ac-coupling

MidNite Solar

http://www.midnitesolar.com/index.php

...

[ncs55]

At one point in time Enphase and Schneider were talking about AC coupling. The problem was how the master inverter would communicate and regulate the power from the enphase system. They achieved this with SMA and from what I read the SMA can be regulated by the XW with frequency shifts. I do not know much about Magnum products or if they will work.

[ncs55]

butch, do you actually read the posts? In no way was I referring to charging a battery with a battery. Of course it is the micros and the AC output of them, and how the XW could use and regulate that power to either feed in the grid or power loads or charge its own batteries.. Enphase was not even thinking about batteries when Schneider was experimenting with AC coupling with other companies.

[Engineer]

Yeah I've read that frequency shifting is one crude way to shut down the u-inverter panels. With the Envoy-S of course they have a more elegant solution by simply communicating with it, as long as there's a local (non-cloud) way to do that, maybe through power line comms.

[ButchDeal]

This thread started on the enphase batteries. The discussion keeps coming around to enphase batteries.
Talking about non-enphase batteries in an AC coupled way is just confusing the topic.

[ncs55]

Engineer commented Today, 07:01 AM
Editing a comment
Yeah I've read that frequency shifting is one crude way to shut down the u-inverter panels. With the Envoy-S of course they have a more elegant solution by simply communicating with it, as long as there's a local (non-cloud) way to do that, maybe through power line comms.


It may be crude but it works great with the XW and SMA. I don't think the envoy has the capability to communicate with any other inverter when AC coupled. The envoy only communicates with the micros, no solution for AC coupling there that i am aware of.

[ncs55]

ButchDeal commented Today, 01:38 PM
Editing a comment
This thread started on the enphase batteries. The discussion keeps coming around to enphase batteries.
Talking about non-enphase batteries in an AC coupled way is just confusing the topic.

Actually it started with this question from the poster.
My question is what would be needed to turn this system from a grid tied to a hybrid? Specifically one that when the grid goes down it cuts itself off from the main grid creating a house micro-grid. Simple minded take is that it needs a mains breaker that cuts out when the system goes down, and a new internal frequency generator for the inverters to synchronize to. Thoughts?

That does not limit this thread to the enphase batteries IMO. Especially when the enphase batteries will not work in a hybrid solution and a master inverter would be needed and it would most likely have to be AC coupled with the Enphase system.

[ButchDeal]

go back and look at comment 7.1 by OP.

[ncs55]

Butch, That is the question yes. And the only way I see to make this system be off grid is by not using the enphase batteries for the reason that you stated earlier that that battery pack is not designed for this application. And as the enphase would need to sense what they think is a grid to operate, they would need to be ac coupled to a master inverter with its own battery array as enphase is not intended for hybrid or off grid use. The master inverter, if ac coupled with enphase will need to control the power from the enphase system and or communicate with it somehow.

[ncs55]

ButchDeal commented

Today, 04:08 PM




that is the answer we all gave but OP keeps trying to find a way to make the enphase battery be off grid.
The answer is simple, you can't

The question is specific and is, how can he turn this system into off grid. Not how to make the enphase batteries go off grid. You are right the enphase batteries wont work. I have read others in other forums that have actually been experimenting with ac coupling the enphase systems. I do not know if they have had success. If you wanted to make this a safe hybrid, I would recommend calling Schneider and asking if there is a way to make it work with their product and calling SMA and asking if it can work with their product. Or whichever other product that it may be AC coupled with. I would not try and re invent the wheel with a product like enphase. If you want to go hybrid or off grid, then simply sell the enphase system and use the modules in a correctly designed system for the application IMO. Engineer has the best answer and I missed that post earlier.

[Engineer]

encs55 gets it, thank you.

Enphase batteries are not meant for off grid - obviously. However, I don't see why they can't be used as part of an off grid system. Just imagine an off grid system, wether you have enphase batteries in there or not shouldn't matter. They'll still behave the same, pulling from the panels to charge and giving back as you desire.

There might be some specific technical reason this doesn't work, but I'm seeing a lot of "because it won't work" which isn't helpful.

[ButchDeal]

They can't be used because if you attempted to then the bymodal inverter would be charging its batteries from the enphase battery. This would have the enphase batteries cycling way too much. you would have a lot of losses converting from solar DC, to AC at the micro then bac to DC at the enphase battery, then bac to AC at enphase battery, back to DC at bimodal inverter to charge bimodal batter. Then latter back to AC at bimodal inverter for use.

Though the current method of controlling the enphase micros would likely work for getting power out of the battery, it wouldn't work well for getting power in since the control would be with the bimodal inverter which would regulate the micros based on the bimodal said needs and no concern for any AC batteries.

[ncs55]

Engineer commented Today, 05:15 PM
Editing a comment
encs55 gets it, thank you.

Enphase batteries are not meant for off grid - obviously. However, I don't see why they can't be used as part of an off grid system. Just imagine an off grid system, wether you have enphase batteries in there or not shouldn't matter. They'll still behave the same, pulling from the panels to charge and giving back as you desire.

There might be some specific technical reason this doesn't work, but I'm seeing a lot of "because it won't work" which isn't helpful.

To be honest, I don't know enough about their battery packs. I am going to research them a little further. But from what I gather from here, they would probably fail pretty quick in an off grid application. Or just not last very long. I usually sell LA with a hybrid or off grid because, albeit they are a lot of maintenance, We can stand behind them and get better than average life from them. I reference the XW because we have a lot in the field, and they are working great in both modes. I do not see any way around somehow AC coupling to achieve what you want. A generator and a transfer switch will not give you this effect with enphase and would be dangerous. That's why you need a product that has a better brain and can manage the power coming in from multiple sources.

[sensij]

One problem with the Enphase battery is the same problem you have with any solar powered off-grid system... there needs to be a controller that can limit the power in the microgrid. Hybrid inverters can do this by disconnecting or throttling back the panels through the charge controller (operating away from MPPT) when they could be producing more power than what can be consumed (by the loads and battery). Enphase does not appear to support this capability in their battery system, so it looks like a dead end for off-grid use.

The data sheet suggests there is "power export limiting". If that were to be fully developed and responsive enough, it might be a path forward.