- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
If the SI is not monitoring the current, you might be able to use an external ATS?
If the SI is not monitoring the current, you might be able to use an external ATS?
I don't think you can connect all the Tripowers on the AC side of the SI's.
I think that the original thread topic took a turn near the end to consider what would be needed for the tripowers to produce local power during a grid outage.But if the power coming from the Tripowers is going:
A. Out to the grid
or
B. In to the main load panel
Wouldn't this edited drawing work?
Is there any reason that you would *have* to use Sunny Islands?
It doesn't seem 100% necessary when there isn't any PV going through them.
http://1drv.ms/1d8tndN
If you want the system to be able to run offgrid, i.e., when the grid is down, you must have batteries and battery compatible inverters*. Tripowers are not battery compatible. Sunny Islands are battery compatible, but they are not PV compatible.But if the power coming from the Tripowers is going:
A. Out to the grid
or
B. In to the main load panel
Wouldn't this edited drawing work?
Is there any reason that you would *have* to use Sunny Islands?
It doesn't seem 100% necessary when there isn't any PV going through them.
But if the power coming from the Tripowers is going:
A. Out to the grid
or
B. In to the main load panel
Wouldn't this edited drawing work?
Is there any reason that you would *have* to use Sunny Islands?
Or something like page 2 here?
http://www.morningstarcorp.com/wp-content/uploads/2014/05/MSC-Diagrams-TS-MPPT-600V-150520-09-MG.pdf
Sunny Islands are battery compatible, but they are not PV compatible.
I think that the original thread topic took a turn near the end to consider what would be needed for the tripowers to produce local power during a grid outage. ...
You cannot connect PV modules to a Sunny Island* and you cannot connect batteries to an SMA Tripower. Isn't that what I said?I don't think you meant that last part exactly as you said it.
If you want the system to be able to run offgrid, i.e., when the grid is down, you must have batteries and battery compatible inverters*. Tripowers are not battery compatible. Sunny Islands are battery compatible, but they are not PV compatible.
It would work in the sense that you would have some back up supply for critical loads if the utility power went out. It would not work for keeping the building powered if the outage was long and the batteries drained. It would also not work for time-storage shifting.
Sunny Islands can tell the difference because the PV inverters connect to one AC connection and the grid connects to the other. Also, if this new Sunny Island is 240V split phase (I haven't seen one), how do you plan to interface it with the 480V three phase output of the Tripower inverters?There are these new ones.
So two of these, the 8.0 model, would have maximum input of 100A (50A each) at 240V, and are rated to put out 6000w/26A each at 240V.
They wouldn't know the difference between power coming from the Tripowers and power coming from the grid.
You cannot connect PV modules to a Sunny Island* and you cannot connect batteries to an SMA Tripower. Isn't that what I said?
*You can, however, connect PV modules through a charge controller to batteries and then connect the batteries to a Sunny Island.
Sunny Islands can tell the difference because the PV inverters connect to one AC connection and the grid connects to the other. Also, if this new Sunny Island is 240V split phase (I haven't seen one), how do you plan to interface it with the 480V three phase output of the Tripower inverters?
Aren't the first two just a matter of how many amps of storage you have? And if you check out that link, those 8.0 models are supposedly great for time shifting.
You cannot connect PV modules to a Sunny Island* and you cannot connect batteries to an SMA Tripower. Isn't that what I said?
And what makes the SI/SB combination unique AFAIK, is that as the SI sees its output approach zero (SBs are meeting entire local load including battery charging) it can modulate the SB output (not just on/off as with other AC coupling schemes) by increasing the frequency above nominal.
My point was that you are ignoring the option of having the PV recharge the batteries if the grid is out. Personally, if I was paying for both battery backup and for solar I would want them to work together when the power went out. But I have yet to see how that's economical for anyone except maybe some large industrial customers. Give it five years and that may change.
The Tripowers will shut down when the grid goes down in that configuration. The SI has two AC connections - one to the MDP and grid and one to the protected loads panel. Only the connection to the protected loads panel stays energized when the grid goes down (dictated by UL1741 and physics), and any PV inverters that you want to keep running during a outage must be connected to the protected loads panel; their connection to the grid is through the Sunny Island. The Sunny Island is connected to the MDP through OCPD sized for its maximum current, which also limits the size of the PV inverter that you can connect through it to the MDP.Am I missing something here?
The Tripowers are connected to a line side junction box which goes to grid or load.
The Islands are connected to the load side of the main service box.
There's a 480/277 to 120/240 xfmr between the junction box and main service box.
So how are the TPs and SIs connected?
If the grid goes down, the Tripowers will run the load (which includes charging batteries), or shut down if there's no load and batteries are full?
The wiring of the "load area" is currently 120/240. So the 120/240 xfmr would be supplying the 120V load, and using the two lines of 120V to make 240V for the SIs.
IMO something you should consider is how important it is for the PV to continue to run during a grid outage. ...The contribution to your customer's bottom line from PV running during outages is minuscule if outages are infrequent and/or of short duration
I believe that the correct way to think of it is as two separate systems - the PV system and the battery backup system. A PV system never has output when sunlight is not available. A battery system (when the batteries are charged) has output whenever it is needed. A PV system (a current source with its voltage clamped) produces the amount of power that the array captures from the available sunlight - no more, no less - and it has to go somewhere or the system shuts down*. A battery backup system (a voltage source) provides the amount of power that the loads demand. They are different tools for different tasks.How do you explain it in layman's term (meaning: to me)?
Having a battery bank....makes your PV system have an output when the sun is not up.
The SI has two AC connections - one to the MDP and grid and one to the protected loads panel. Only the connection to the protected loads panel stays energized when the grid goes down (dictated by UL1741 and physics), and any PV inverters that you want to keep running during a outage must be connected to the protected loads panel; their connection to the grid is through the Sunny Island.
That implies that the tripower can function on all three phases with only one "grid qualified" reference phase. This would have to bevatotslly different mode of operation from the normal grid tied modevin whichbesch phase follows the timing and voltage of its corresponding grid phase.Right. But!
First of all, what's going on here?
It's in German, that doesn't help.
It looks like the SI is only hooked up to ONE Of the 3 phases of the grid here. Huh?
http://www.sma-america.com/fileadmin/_migrated/pics/summenstrom_01.jpg
And then, never mind that- regarding your quote above-
If the MDP and grid are both getting power from the Tripowers, and the MDP includes the SIs, and then the grid goes down, the Tripowers will throttle down and supply the load instead of grid, won't they?
This goes with that link/pic above.
Although the Sunny Island is only connected to one line conductor, it automatically manages the total power. The energy meters work in a cumulative manner, so that the power from the individual line conductors is added up. The Sunny Island can then always feed in or draw as much energy as is needed in accordance with the sum total of all phases. http://www.sma-america.com/products...ed-self-consumption.html#sthash.N6XDLcQN.dpuf
it has to go somewhere or the system shuts down*.
*An exception is the SI/SB system where the SI throttles back the SB when necessary to fit the demand, but there are specific ways that such a system must be designed and configured in order for it to function this way.
I am skeptical or confused.