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Old 03-23-2016, 10:25 PM   #1
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Default Solar interconnect issue

I was asked to take a look at a home with 10.5 kw of solar on the roof, transfer witch for a generator, and 2 Outback inverters. The complaint that the customer had is that they had the system for 2 years, and consistently have a $ 200.00 per month electric bill. The system will not draw the power from the inverters when they are in grid tie mode, only when they are in islanding, or non-grid tie mode. This creates a problem at night when the grid is needed. The installing company cannot figure it out, and gave up.
The inverters output backfeeds the main breaker panel through two double pole breakers. My thought is to install a contactor with the grid power going through it and use the auxillary output from the inverter to energize the contactors coil when the inverters are not producing.

Has anyone had an experience with this or seen this issue? I have a little solar experience but not an expert.

Thanks
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Old 03-23-2016, 10:35 PM   #2
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Which model inverter? You say they island? How is that possible? A grid tie inverter shuts down when the grid goes away. Or is this a hybrid system with batteries? Also a wire schematic would help.
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Old 03-23-2016, 10:41 PM   #3
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Yes, it is hybrid with charge controller and batteries. I will sketch it out.
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Old 03-23-2016, 10:51 PM   #4
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Yes, it is hybrid with charge controller and batteries. I will sketch it out.
Which inverter? Is islanding is not the term for when it's off grid tie and powering loads. Islanding refers to inverters that try to power the grid when the utility is down.
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Old 03-23-2016, 11:00 PM   #5
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The OP totally lost me.

AFAIK, the ONLY type of PV installation that gets Federal tax credits is the grid-tied scheme.

If you build an off-the-grid PV array -- no tax breaks for you.

The OP is logically inconsistent, as PV needs sunlight to produce DC power, and that DC has to be inverted for common usage.

Inverters that don't work in the daytime = the system can't work at all.
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Old 03-23-2016, 11:16 PM   #6
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The OP totally lost me.

AFAIK, the ONLY type of PV installation that gets Federal tax credits is the grid-tied scheme.

If you build an off-the-grid PV array -- no tax breaks for you.

The OP is logically inconsistent, as PV needs sunlight to produce DC power, and that DC has to be inverted for common usage.

Inverters that don't work in the daytime = the system can't work at all.
It's a storage system. Once the batteries are full, it sells to the grid. I have a customer with two FX inverters that are setup in a stacked config to produce 240. He has just a pair of 12 volt marine batteries and he sells back to the grid what the house doesn't use. With the FX inverter, there is an AC in that the selling is done on. An AC out that powers loads from the batteries when no grid is present. And powers them with the grid when present. Radians have a bidirectional input, that is the utility and nonbacked up loads. An AC in for the generator. An AC out for the battery backed up loads.
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Old 03-23-2016, 11:35 PM   #7
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Drawing should be attached. I'll have to check the model # of the inverters.
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Old 03-23-2016, 11:45 PM   #8
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Why do you have two battery banks? Are these inverters and charge controllers connected to a Hub and a Mate? If not I don't think it will work. You need one inverter as a master and one as a slave.
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Old 03-24-2016, 12:01 AM   #9
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http://www.outbackpower.com/download...1-00_REV_A.pdf
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Old 03-24-2016, 12:15 AM   #10
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Yes, I failed to show on the diagram there are a total of 4 inverters. 2 on one charge controller and 2 on the other. The homeowner did say that on each set one is supposed to be a master and one is supposed to be a slave. Also, I did see cat5 cables at the inverters but I didn't pay much attention to them thinking they did nothing with the system. Now it appears they might. I didn't see a hub though. There is also a little programming module next to the inverters to set them up.
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Old 03-24-2016, 12:25 AM   #11
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You need a device called a hub and a mate. I also think you can only have one master. The other three are slaves.
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Old 03-24-2016, 08:03 AM   #12
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I do not have solar experience so if I make a dumb comment, please excuse me.

I'm assuming this setup is using a net meter. Could the problem be as simple as something is wrong in the net meter, or is that an impossibility?
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Old 03-24-2016, 08:20 AM   #13
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I do not have solar experience so if I make a dumb comment, please excuse me.

I'm assuming this setup is using a net meter. Could the problem be as simple as something is wrong in the net meter, or is that an impossibility?
I don't think so. I've never seen two separate systems trying to run together like this. I think the installer didn't wire the communication part correctly. It needs one battery stack, a hub and a mate. One inverter setup as the master and the rest as slaves and it will run. Once that is done and programmed, it will take off on its own. Thing is, Outback will walk you through it if you call them.

Did the HO pay for a job not completed? I wouldn't. And how do you run a company where you can't get equipment you install to run because of lack of knowledge? Give the OP credit, he asked for help.
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Old 03-24-2016, 01:33 PM   #14
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You have given us the drawing of the battery inverter system. Where is the Solar PV connection? How can the PV sytem feed into the grid to reduce usage when it appears the PV array is used only to charge the batteries?
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Old 03-24-2016, 03:18 PM   #15
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You have given us the drawing of the battery inverter system. Where is the Solar PV connection? How can the PV sytem feed into the grid to reduce usage when it appears the PV array is used only to charge the batteries?

Correct me if I'm wrong, but the way I see it is the PV array feeds the batteries, then the inverter draws DC from the batteries to send AC on the output. They system says batteries have 100% charge..


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Old 03-24-2016, 03:33 PM   #16
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I don't think so. I've never seen two separate systems trying to run together like this. I think the installer didn't wire the communication part correctly. It needs one battery stack, a hub and a mate. One inverter setup as the master and the rest as slaves and it will run. Once that is done and programmed, it will take off on its own. Thing is, Outback will walk you through it if you call them.



Did the HO pay for a job not completed? I wouldn't. And how do you run a company where you can't get equipment you install to run because of lack of knowledge? Give the OP credit, he asked for help.

It's actually 2 separate systems. I tried to show on the drawing 2 different load centers. 2 of the inverters feed one and the other 2 feed the other load center. On each pair of inverters one is master and one is slave. Both of the load centers however share the same grid service connection.

I believe the original installing company had others look at it and they couldn't solve it either. I think they did get paid though somehow.


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Old 03-24-2016, 03:37 PM   #17
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You still need a hub, and in this case, two . And two mates. Some pictures and inverter mod#s would be nice.

As long as you have the ins and outs correct, and the inverters and charge controllers are communicating. The Outback inverters will sell, they are really plug and play.

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You have given us the drawing of the battery inverter system. Where is the Solar PV connection? How can the PV sytem feed into the grid to reduce usage when it appears the PV array is used only to charge the batteries?
The system is correct as far as the PV to the charge controllers to the batteries.
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Old 03-24-2016, 05:05 PM   #18
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You still need a hub, and in this case, two . And two mates. Some pictures and inverter mod#s would be nice.

As long as you have the ins and outs correct, and the inverters and charge controllers are communicating. The Outback inverters will sell, they are really plug and play.



The system is correct as far as the PV to the charge controllers to the batteries.

They have two hubs and 2 Mate2's. I won't be back there until Tuesday to get the model #'s. I can send a picture this eve.

I did find out that the boards were changed out to a different style because they didn't want to sell power and just use what they generate.

Could programming be the issue if the home will draw power from the inverters when they are not in grid tie mode but not draw inverter when they are in grid tie mode?


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Old 03-24-2016, 09:38 PM   #19
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Here are pictures of the inverters. Sorry about the quality.
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Old 03-24-2016, 09:58 PM   #20
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They look like FX inverters. Master must be connected to Hub port 1, slave any port higher. Mate into the 1st Mate port. If you need to go through the programming, I could help. But we'd have to do it over the phone with you on site.

There is some programming, Power Save Levels need to be set. Sell Settings( sell re) and (grid tie window)
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