Re: [RE-wrenches] SMA Micro-grid

louis Thu, 25 Apr 2019 10:10:58 -0700

The Inverters do not know what the wattage will be until they attempt to connect(go into GRID Monitoring routine) and then evaluate the conditions.

If the PV voltage is over the Start voltage they will act on this.

If by just entering the GRID-Monitoring the PV voltage collapses(not enough minimum power) the Inverter will typically fall out of GRID-Monitoring and repeat the process etc.

The Inverter however does not just stay in waiting, it typically cycles through GRID-Monitoring, Waiting...

This is where the PV Start voltage can come into play and the installer can increase this start voltage to minimize the amount of time the Inverter spends cycling through GRID-Monitoring/Waiting.

When the Inverter spends allot of time doing this(Morning & Night) it needlessly causes the GRID Relays to be worked.

Keep the VMPP high and this reduces the chances of this activity.

Louis Segarra

-------- Original Message --------
Subject: Re: [RE-wrenches] SMA Micro-grid
From: Solar <[email protected]>
Date: Wed, April 24, 2019 4:03 pm
To: RE-wrenches <[email protected]>

I have three SB 700 for my solar class. When we get the “waiting” on our LCD we are always well above the required VOC. A call to SMA years ago lead me to finding that there is a “wattage In”rating I need to meet to get the inverters to grid tie. I never saw this in the manual. These inverters have a narrow V and I window so finding modules for the lab was tricky. I had used 75V/1.4A modules for the stings to meet the 115-150Vdc range and a 2A max input rating. Connecting two of these in series never would take the inverter out of “waiting” mode unless it was blue bird skies and we tilted to array right at the sun. I finally put three or four in series on a (500w/m squared) cloudy day and the inverter immediately tied to the grid. Going back to 2 in series left it in waiting. That’s when I called and asked about a min current input rating and was told about the not listed wattage (I was told power) In rating.

Not sure if this applies to you but it was a great lesson for the students.

Jesse Dahl

NABCEP PV Installation Professional
IBEW Local 292 - Electrician
Electrical/Solar PV Instructor - HCC

Sent from my iPhone

On Apr 23, 2019, at 2:21 PM, Harry Mahon <[email protected]> wrote:

William - yes, waiting is usually waiting for grid to come back within spec or for DC voltage to get to start. 260 should be plenty. 208V with neutral should be fine without adjusting the jumpers. Have you measured the AC voltage at the inverter terminals?

May want to contact service for this one. 1-877-697-6283.

Best regards –

Mike

From: William Miller <[email protected]>
Sent: Tuesday, April 23, 2019 12:40 PM
To: Harry Mahon <[email protected]>
Cc: RE-wrenches <[email protected]>
Subject: Re: [RE-wrenches] SMA Micro-grid

Mike:

Thanks for the reply. Good information.

The AC system is 208. The data sheet indicates that for 208 the PV startup is 220. Today we have 260 VDC. That should be enough!?

I checked EMT he AC frequency in case it was on shift mode. It is right at 60.00.

Still in waiting mode. I had always thought “waiting” was for grid reconnect timeout...

William

On Apr 23, 2019, at 8:47 AM, Harry Mahon <[email protected]> wrote:

William –

Waiting mode means the DC voltage is below the inverter start. For SB 4000-12, that would be 285 VDC (and will work to 250VDC once that is hit).

If you knock on the inverter lid, the display will cycle and you will see the DC voltage displayed.

If the yellow LED is not on, this should not be an AC side issue.

I do not think the “Backup Mode” parameter would be the cause, but if the voltage check shows well above PVstart, it would be worth a call to service. If the inverter was left in on grid mode, then it will work when the SI is creating a micro-grid with frequency within UL1741 limits. If the system is off-grid, I would think the SB would have been set to off-grid mode rather than enabling Backup Mode to “on all” that allows switching from on-grid to off-grid parameter sets by RS485 command.

Best-

Mike

From: RE-wrenches <[email protected]> On Behalf Of William Miller
Sent: Monday, April 22, 2019 6:54 PM
To: RE-wrenches <[email protected]>
Subject: [RE-wrenches] SMA Micro-grid

Friends:

I am working on an AC coupled SMA system in an off-grid setting. We have an SB4000-12 that was disconnected for a number of years and we reconnected it. The inverter is stuck in the waiting mode and will not generate power. The Sunny Islands and Sunny Boys are connected via an RS485 communication system.

I suspect there is a programming step I have not yet accomplished. I recall some years ago I programmed the other Sunny Boys for off-grid operation. I can’t find anything in any of the manuals about how to check the programming. I also suspect SAM tech support talked me through this and the information may not be published.

Does this ring a bell with any of you? Any advice?

Thanks in advance.

William Miller

Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com

CA Lic. 773985

Quote of the day: “If there is a job you hate, get really,

really good at it. Maybe you will hate it less.“ W. Miller

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Re: [RE-wrenches] SMA Micro-grid

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