Enphase getting into storage systems...

[Sunking]

GTI are current sources, not voltage. They need very low impedance of the grid to operate properly.

[paulcheung]

I can see the gridtie users hate to see their PV power gone wasted when the grid is down, If the grid is not reliable then you should not have grid tie installaion in the first place! If the grid is reliable and just occasionally down once a week or month for few hours, You have a lot of other opions to power the whole house with a generator or an UPS just to power some critical circuits like computer and modems.

It is just not econmical sensible to has a grid tie system and then spend lot of money use battery backup to save the little power produced by the PV panels.

Yes you can use a something to fool the grid tie inverter to start, but what happen to the buffer resource when the cloud pass by? you don't feel any problem because the grid is buffer all the demand when the grid is up, BUT when it is down, you try to use battery buffer that. see how much money you have to spend to get that done. might as well do it off grid from the first place.

When you on grid tie, you usually don't conserve, use the power as you like and have all the air condition running and other big current drawing eqipments, I just don't see it make any sense at all to mess with the installation.

Cheers

[fun2drive]

I can see real value in a system that does the grid tie to be dropped when utility power fails and allow self contained operation. I read about the SMA Sunny Boy inverters that do this but the lack of power output that would allow running appliances with induction motors would require some buffer like a battery storage to allow that powering up that LRA use.
I really desire an application which would allow a safe seamless change over from grid tie to stand alone and back once utility power. At the moment my only real choice is a generator and automatic transfer switch if utility power goes down...

Interesting idea but I would agree seems to be a limited market for this type of application.

[kwilcox]

Now that I've spent some time thinking about how it is connected, I can't personally see how it can easily be anything else. Maybe dedicated branch circuit connected to generation/storage system? The interesting point against this is the following bullet which implies GT operation:

• Intelligent system maximizes utility bill savings and battery life

To do this, it also needs to know whole-house usage at any given point in time which pretty much requires something like a CT on the POCO feeder.

edit: and here's how (I should've just read inetdog's post first lol)...

http://enphase.com/eblog/2014/new-en...olar-adoption/

It looks like I might just have lucked out by choosing an enphase engage based system....

[nomadh]

I still have not seen any documentation to the effect that the new Enphase system with storage can be used in an off grid mode. The website touts it as ideal for use with a POCO connection that does not allow sell back into the grid. So it can instead store excess energy in the battery and provide it back through the grid tie when needed once the sun is down.
That would not take particularly sophisticated engineering, not much change in the hardware of the micro-inverter units. Beyond the CC and storage, the biggest additional requirement for the system would have to be a current transformer and voltage probe arrangement to allow it to detect the amount of power being drawn from the grid. As that number approaches zero, it would divert panel energy from the inverter to the CC.

The same power sensing equipment, if placed downstream of a transfer switch, would allow the unit to be used safely in conjunction with a generator that takes the place of the grid.

PS: The idea that the Enphase storage system, even if it can be used in an off-grid mode, could be used to "jump start" a system of conventional microinverters would still be a failure because it would have no way to throttle the output of the normal GTI inverters. The best it could do would be to reduce its own output to keep the effective load above the GTI output. Once the load goes below the current output of the conventional GTIs alone the system will fail, either gracefully by shutting down completely, or catastrophically by letting out magic smoke.
I doubt that the system includes an AC input CC which would allow it to suck up extra GTI output (until the batteries get full!), but if does it becomes much more interesting.

It seems that this product is very close doing offgrid power. It doesn't need a lot of extra cost to do this. Sunnyboy is including the feature at no real extra cost. The microinvertes have some intelligence and a unit like this could sense a load and then turn on or off inverters to match with the battery as a buffer. 1 battery for a small buffer and 2 or 3 for a pretty big buffer to handle things like a fridge.
I think the extra cost could be negligible but there seems no interest in this country. Frankly it has me log jammed. I find it stupid that if I have 6kw on my roof I should be able to use it somewhat in an emergency. Without a lot of extra cost. I don't need to run my whole house. It doesn't need to be super convenient. Power during the daytime only is ok. It should be optimized for shade all the rest of the time. I shouldn't have to buy something like enphase or solar edge THEN also buy a sunnyboy inverter and its wiring to store in my garage just in case an extended grid down period. But I think this is still a better answer than a triple priced inverter and doubling the price of my system again with batteries and then costing me 50% again in 7 years to replace my batteries and in 7 years again.
I was all set to buy the agnostic solar edge power power optimizers and then the sunny boy inverter but those power optimizers aren't available in the U.S. Like I said total logjam.

[nomadh]

Duplicate

[inetdog]

I still have not seen any documentation to the effect that the new Enphase system with storage can be used in an off grid mode.[/B] The website touts it as ideal for use with a POCO connection that does not allow sell back into the grid. So it can instead store excess energy in the battery and provide it back through the grid tie when needed once the sun is down.
That would not take particularly sophisticated engineering, not much change in the hardware of the micro-inverter units. Beyond the CC and storage, the biggest additional requirement for the system would have to be a current transformer and voltage probe arrangement to allow it to detect the amount of power being drawn from the grid. As that number approaches zero, it would divert panel energy from the inverter to the CC.

The same power sensing equipment, if placed downstream of a transfer switch, would allow the unit to be used safely in conjunction with a generator that takes the place of the grid.

PS: The idea that the Enphase storage system, even if it can be used in an off-grid mode, could be used to "jump start" a system of conventional microinverters would still be a failure because it would have no way to throttle the output of the normal GTI inverters. The best it could do would be to reduce its own output to keep the effective load above the GTI output. Once the load goes below the current output of the conventional GTIs alone the system will fail, either gracefully by shutting down completely, or catastrophically by letting out magic smoke.
I doubt that the system includes an AC input CC which would allow it to suck up extra GTI output (until the batteries get full!), but if does it becomes much more interesting.

[CA_Tom]

[B]
I doubt that the system includes an AC input CC which would allow it to suck up extra GTI output (until the batteries get full!), but if does it becomes much more interesting.

From what I can tell, the system ONLY has an AC input/output - the "Engage" cable.

http://enphase.com/wp-uploads/enphas...Brochure-1.pdf

So if the only connection is the AC line, then it must have an AC input CC.

It seems to me that with just a little extra intelligence it could be setup to do an off-grid mode. It'd need an extra box near the main panel to make sure it was isolated from the grid (for safety). And it'd probably need some extra intelligence to be able to start a sine wave (vs. matching an existing one.) And some intelligence to talk with the other microinverters and coordinate inverter output / battery charging to keep the voltage stable.

I don't see anything in that brochure that indicates that's what they've done. And I don't know that there's a big enough market to make it worthwhile to do that. But i don't think it's impossible.

[kwilcox]

...and as such, from a design perspective (implementation perspective still tbd however), it'll pretty much be precisely what those of us facing increasingly hostile POCO tariffs are looking for.

[inetdog]

Anyone know if this battery system can be used to "start up" some of the micro inverters during daytime to give you downed grid power? It seems possible that a unit like this could inject a sinewave and communicate with inverters turning them on or off as needed by the load demand using the battery as a big buffer capacitor. Similar to sunnyboy on demand power. If it isnt too much money. Or if it even does it at all. Its been implied but does anyone know if it will have this ability.

I still have not seen any documentation to the effect that the new Enphase system with storage can be used in an off grid mode. The website touts it as ideal for use with a POCO connection that does not allow sell back into the grid. So it can instead store excess energy in the battery and provide it back through the grid tie when needed once the sun is down.
That would not take particularly sophisticated engineering, not much change in the hardware of the micro-inverter units. Beyond the CC and storage, the biggest additional requirement for the system would have to be a current transformer and voltage probe arrangement to allow it to detect the amount of power being drawn from the grid. As that number approaches zero, it would divert panel energy from the inverter to the CC.

The same power sensing equipment, if placed downstream of a transfer switch, would allow the unit to be used safely in conjunction with a generator that takes the place of the grid.

PS: The idea that the Enphase storage system, even if it can be used in an off-grid mode, could be used to "jump start" a system of conventional microinverters would still be a failure because it would have no way to throttle the output of the normal GTI inverters. The best it could do would be to reduce its own output to keep the effective load above the GTI output. Once the load goes below the current output of the conventional GTIs alone the system will fail, either gracefully by shutting down completely, or catastrophically by letting out magic smoke.
I doubt that the system includes an AC input CC which would allow it to suck up extra GTI output (until the batteries get full!), but if does it becomes much more interesting.

[PVAndy]

Andy

You are correct. Thank you for correcting my post.

There are some high end hybrid systems that have the right isolating equipment to prevent back-feeding the grid yet still allow the pv panels to generate power. They cost a lot and aren't really considered by most people that just want their panels to provide full power when the grid goes down.

I got the impression that nomadh was looking for a simple device to "fool" the grid tie inverters to work when the grid was down instead of using a fully designed hybrid system that you have hands on experience.

Lol I didn't say they are cheap! Typically just the "off grid" inverter costs 3 - 7K. And the designs which at first seem simple are anything but. The installation and programming (yes there is a lot of programming) are typically 100 to 200 pages long (and hard to read)

[SunEagle]

SunEagle I respectively disagree. I have designed and installed systems both with Enphase Microinverters, Power One & SunnyBoy String Inverters that operate in a Grid Tied Hybrid mode. Outback models like the Radian and the SMA Sunny Island can both produce AC clean enough to start a string or microinverter. In both cases they have internal transfer relays that serve to disconnect the inverters from the grid when the "simulated grid" is up. This is commonly referred as AC Coupling.
At this point I can't say more about the Enphase product as I am under nondisclosure with them.

Andy
NABCEP Certified PV Installation Professional
Solar Design Engineer

Andy

You are correct. Thank you for correcting my post.

There are some high end hybrid systems that have the right isolating equipment to prevent back-feeding the grid yet still allow the pv panels to generate power. They cost a lot and aren't really considered by most people that just want their panels to provide full power when the grid goes down.

I got the impression that nomadh was looking for a simple device to "fool" the grid tie inverters to work when the grid was down instead of using a fully designed hybrid system that you have hands on experience.

[PVAndy]

It takes more than providing a sine-wave to get grid tie inverters to work. As of now there isn't a device that can mimic the GRID and because there is a danger of solar pv "back-feeding" the grid when it is down and killing someone. I would believe there will be very high resistance in allowing a device to be marketed.

SunEagle I respectively disagree. I have designed and installed systems both with Enphase Microinverters, Power One & SunnyBoy String Inverters that operate in a Grid Tied Hybrid mode. Outback models like the Radian and the SMA Sunny Island can both produce AC clean enough to start a string or microinverter. In both cases they have internal transfer relays that serve to disconnect the inverters from the grid when the "simulated grid" is up. This is commonly referred as AC Coupling.
At this point I can't say more about the Enphase product as I am under nondisclosure with them.

Andy
NABCEP Certified PV Installation Professional
Solar Design Engineer

[SunEagle]

Anyone know if this battery system can be used to "start up" some of the micro inverters during daytime to give you downed grid power? It seems possible that a unit like this could inject a sinewave and communicate with inverters turning them on or off as needed by the load demand using the battery as a big buffer capacitor. Similar to sunnyboy on demand power. If it isnt too much money. Or if it even does it at all. Its been implied but does anyone know if it will have this ability.

It takes more than providing a sine-wave to get grid tie inverters to work. As of now there isn't a device that can mimic the GRID and because there is a danger of solar pv "back-feeding" the grid when it is down and killing someone. I would believe there will be very high resistance in allowing a device to be marketed.

[nomadh]

Anyone know if this battery system can be used to "start up" some of the micro inverters during daytime to give you downed grid power? It seems possible that a unit like this could inject a sinewave and communicate with inverters turning them on or off as needed by the load demand using the battery as a big buffer capacitor. Similar to sunnyboy on demand power. If it isnt too much money. Or if it even does it at all. Its been implied but does anyone know if it will have this ability.