Answered

automatic transfer switch

Posted by blade3609

Aug 10, 2019 at 8:10am

Has anyone ever used this "Xantrex 8080915 PROwatt SW Auto Transfer Switch" or "MOES Dual Power Controller 50A 5500 Watt Automatic Transfer Switch for Off Grid Solar Wind System ATS DC 12V 24V 48V AC 110V 220V" in there solar setup. Any input would be greatly appreciated.


Posted by mediadogg

Aug 10, 2019 at 8:47am

I use two of "Xantrex 8080915 PROwatt SW Auto Transfer Switch", for almost 3 years now. So they are robust. The transfer time is relatively slow for sensitive equipment such as computers, so I actually feed the output of the ATS to my computer battery-backed UPS that prevent my computers from seeing the power glitch.

More recently, I have got a couple of the other ones: "MOES Dual Power Controller 50A 5500 Watt Automatic Transfer Switch for Off Grid Solar Wind System ATS DC 12V 24V 48V AC 110V 220V"

They seem to have a much faster switching time, and I can regulate the switch points based on the battery voltage, which serves also to protect the battery. It helps make the grid to solar (and back) transitions fiddle free. I have one that switches based on battery voltage, and my other switches on power loss by sensing the loss of 12VDC from a little power brick plugged into the mains. I do have the problem that every now and then, the ground fault protection trips on my Samlex inverter. I have the grid / out / inverter grounds tied together in my installation. I think I need to disconnect the inverter ground, someday when I get around to it.

Posted by blade3609

Aug 10, 2019 at 8:52am

Thats great man! Thanks for your input.

How can you solve the issue of the ground fault protection trip on the inverter? because i also heard this and it can also damage the inverter after a while, what some people have claimed.

Posted by mediadogg

Aug 10, 2019 at 9:00am

blade3609 Avatar

Aug 10, 2019 at 8:52am blade3609 said:

Thats great man! Thanks for your input.

How can you solve the issue of the ground fault protection trip on the inverter? because i also heard this and it can also damage the inverter after a while, what some people have claimed.


Not sure. I haven't figured it out yet. I called Samlex about it and their engineer suggested that I just replace the ground fault socket with a regular one. I didn't like the sound of that ...

Posted by blade3609

Aug 10, 2019 at 9:25am

I dont like that idea either lol... maybe the response is way to fast so it triggers the trip? I have a "Spartan Power 50A 5500 Watt Automatic Transfer Switch Great for Solar & Wind Off Grid Systems" (which is the same as the MOES) , but never actually used it yet.. after reading that it might damage my inverter after a while due to many GFCI trips. Im going to buy "Xantrex 8080915 PROwatt SW Auto Transfer Switch" instead then, and use it combined with my UPS.

Posted by mediadogg

Aug 10, 2019 at 9:53am

blade3609 Avatar

Aug 10, 2019 at 9:25am blade3609 said:

I dont like that idea either lol... maybe the response is way to fast so it triggers the trip? I have a "Spartan Power 50A 5500 Watt Automatic Transfer Switch Great for Solar & Wind Off Grid Systems" (which is the same as the MOES) , but never actually used it yet.. after reading that it might damage my inverter after a while due to many GFCI trips. Im going to buy "Xantrex 8080915 PROwatt SW Auto Transfer Switch" instead then, and use it combined with my UPS.


Good luck. Let's keep each other posted since we are using the same stuff. Another annoying problem is that if you are switching back and forth a lot - during start of day and end of day when the solar is on the borderline, the UPS does slowly drain the battery, drip by drip as it protects the equipment. If you get too many cycles before  the solar stabilizes, then the UPS will shut down. I solved my problem by putting a separate UPS on each of 3 different servers. You will of course have to judge for yourself. It is totally dependent on the individual situation.

Posted by blade3609

Aug 10, 2019 at 10:08am

Sounds good my friend.

I didn't get the last part. what you mean by this? " If you get too many cycles before the solar stabilizes, then the UPS will shut down"

How do you switch using the Xantrex 8080915 PROwatt SW Auto Transfer Switch, does your inverter shutdown when voltage gets low and then it uses utility or do you actually manually switch it off. Or do you use a timer?

Posted by mediadogg

Aug 10, 2019 at 1:29pm

Well it is automatic, so there is no manual options other than pulling the plug. And yes I do use timers to try and make the system even more automatic.

But no matter what you do, during the times when you normally expect for the system to be switched to solar, there will be some combination of weather and sunlight that puts the system right on the edge of switching. So when either your battery protection board or the inverter low-voltage protection shuts off the inverter, the ATS also switches. And then the battery charges up a bit, and the ATS switches the other way, and so on and so on. If that cycle occurs so freaquently that the UPS batteries can't recover their lost charge, then those batteries will slowly deplete to the point where the UPS shuts off.

That's why I like the MOES units. They have hysteresis, so you can delay the switching by adjusting the set points.

There are also a new class of cheap battery protection boards available now. They work great, and you can adjust the set points with 0.1 volt accuracy. If I had known about them earlier, I would not have bought the MOES units. The boards don't handle a lot of power, but they could either switch a relay if necessary to carry your inverter load, or directly control one of these or one of these DC triggered AC switches to control the AC going to the ATS from the inverter.

Since I have several "mini-systems" as I call them, and built things in stages over the years, I have a whole mixed bag of various methods. If I started clean now, I would use the best and cheapest methods for everything.

Simplified Diagram of ATS with UPS and Battery Protection

Posted by blade3609

Aug 10, 2019 at 2:58pm

Those do look nice! i might give them a try, i ordered the Xantrex 8080915 PROwatt SW Auto Transfer Switch today. I noticed you are not using utility as power on the ATS? You only have inverter as power?

Posted by mediadogg

Aug 10, 2019 at 3:06pm

blade3609 Avatar

Aug 10, 2019 at 2:58pm blade3609 said:

Those do look nice! i might give them a try, i ordered the Xantrex 8080915 PROwatt SW Auto Transfer Switch today. I noticed you are not using utility as power on the ATS? You only have inverter as power?


I think my "el cheapo" diagram threw you off. Utility is labelled "GRID" and you see it goes both into the ATS and UPS.

Posted by blade3609

Aug 10, 2019 at 4:35pm

Yes now i see it, i saw it for GRD, as ground haha... thats exactly good, instead of the relay im planning on using a "Aeotec Smart Switch 6, Z-Wave Plus Wireless Control Plug for Home Security Automation, 15A Mini Size, Monitor Power, New Design without USB port " which i already have. I monitor the battery volt on my MPPT controller, and for the desired battery voltage i just send a shutdown command, and a turn on command when the desired battery voltage is reached.

Posted by mediadogg

Aug 10, 2019 at 5:06pm

blade3609 Avatar

Aug 10, 2019 at 4:35pm blade3609 said:

Yes now i see it, i saw it for GRD, as ground haha... thats exactly good, instead of the relay im planning on using a "Aeotec Smart Switch 6, Z-Wave Plus Wireless Control Plug for Home Security Automation, 15A Mini Size, Monitor Power, New Design without USB port " which i already have. I monitor the battery volt on my MPPT controller, and for the desired battery voltage i just send a shutdown command, and a turn on command when the desired battery voltage is reached.


Waaaay Cooool!!!!!

Posted by playersz28

Aug 12, 2019 at 4:06am

The Moes switch says 50A but is that for the 110v? I need a split phase 50A unit to have 240v.

Posted by mediadogg

Aug 12, 2019 at 4:44am

playersz28 Avatar

Aug 12, 2019 at 4:06am playersz28 said:

The Moes switch says 50A but is that for the 110v? I need a split phase 50A unit to have 240v.


Well the Amazon listing title says 50A 5500 Watt, so I assume 110V. Could you use two, switched by the same triggering voltage?

Posted by mediadogg

Aug 12, 2019 at 6:09am

mediadogg Avatar

Aug 10, 2019 at 3:06pm mediadogg said:

blade3609 Avatar

Aug 10, 2019 at 2:58pm blade3609 said:

Those do look nice! i might give them a try, i ordered the Xantrex 8080915 PROwatt SW Auto Transfer Switch today. I noticed you are not using utility as power on the ATS? You only have inverter as power?


I think my "el cheapo" diagram threw you off. Utility is labelled "GRID" and you see it goes both into the ATS and UPS.


OMG there is a bug in my diagram!!! I will fix it later. This whole discussion has caused me to go and look at the actual wiring, instead of relying on my memory. And it also caused me to remember why I actually have an extra ProWatt in one of my systems. I might be able to fix this, if I can get the ground fault issue resolved.


ONE ISSUE WITH THE MOES UNIT: Since is a DC triggered ATS, the MOES does not really care whether there is any actual power coming from the source inputs. Its ATS is being swicthed by the DC trigger, NOT by the presence or absence of Grid power.

This means that if the MOES switches to an input that actually has no incoming power, then your load will fail. It will have no power. I was reminded of this from this discussion. When my inverter ground fault triggers, the inverter AC goes out, but THE BATTERY VOLTAGE IS STILL GOOD, so the MOES stays happily switched to inverter power, even though there is nothing coming in!!! And of course the UPS would then shut off when its battery ran down, and the non-UPS loads would shut down immediately when the ground fault was triggered. I know how to fix this now. I just need to put a small power brick on the solar AC side, and use it to power a relay controlling the battery voltage trigger. I will put all of this in my new diagram. The solution I have now actually uses an extra ProWatt to supply the UPS in case the incoming power goes down, which should never happen as long as the grid is up, but due to the way the MOES is designed, and the way I am configured, it can happen to me.

So one change to the MOES design that would make it perfect, is that it should NOT SWITCH to an unpowered input.


Posted by mediadogg

Aug 12, 2019 at 7:26am

Ok, here is a revised diagram. I use this configuration in two of my mini-systems. The only reason I am using the redundant ATS (ProWatt) is that the MOES can actually wind up being switched to the solar input, even if there is no AC coming on that leg, and the grid leg is still powered, due to the ground fault outlet being tripped on the inverter. The trigger input to the MOES from the battery keeps the MOES switched to the inverter leg, even though there is no AC coming in.

Mini System using both ProWatt and MOES ATS

Posted by blade3609

Aug 12, 2019 at 4:41pm

mediadogg Avatar

Aug 12, 2019 at 7:26am mediadogg said:

Ok, here is a revised diagram. I use this configuration in two of my mini-systems. The only reason I am using the redundant ATS (ProWatt) is that the MOES can actually wind up being switched to the solar input, even if there is no AC coming on that leg, and the grid leg is still powered, due to the ground fault outlet being tripped on the inverter. The trigger input to the MOES from the battery keeps the MOES switched to the inverter leg, even though there is no AC coming in.

Mini System using both ProWatt and MOES ATS


Thats a nice work around buddie!


I hope you find a solution for the ground issue at hand with the MOES. Please do share. But have you narrowed down when it actually trips? or does it trip all the time? depending on the load?

Posted by blade3609

Aug 12, 2019 at 4:55pm

Does the prowatt make buzzing noises? Have you opened it? Whats under the hood? Is it as safe as they claim?

Posted by mediadogg

Aug 13, 2019 at 6:45am

blade3609 Avatar

Aug 12, 2019 at 4:55pm blade3609 said:

Does the prowatt make buzzing noises? Have you opened it? Whats under the hood? Is it as safe as they claim?


I have not narrowed down why and when it trips. Since the system runs seamlessly 99% of the time, I usually forget about it until I notice that the breaker has tripped. Happens a few times a week.

I have not opened the ProWatt. It does not buzz, but there is a mild click indicating a relay inside. I think the default wiring is to prefer the grid input, so I usually have to wire them with the inputs swapped (the input they label "inverter," I connect to the grid and vice-versa). Maybe that has something to do with tripping the GFC. Also, I do not have the inverter frame earth grounded. It floats. That might also be the problem. I admit to not being confident with messing with or understanding how to correctly configure grounding in my systems.



Posted by blade3609

Aug 13, 2019 at 7:58am

when switching through the MOES the GFC tripped on trhe inverter right? not when making a switch on the PROwatt?

Posted by mediadogg

Aug 13, 2019 at 8:36am

blade3609 Avatar

Aug 13, 2019 at 7:58am blade3609 said:

when switching through the MOES the GFC tripped on trhe inverter right? not when making a switch on the PROwatt?


I have not noticed that issue when I have used the ProWatt alone. But of course now, the two I have are being used along with the MOES. Today I just got my solid state relay to be used to toggle the MOES trigger line. If that works, I will be eliminating the ProWatt from the configuration to free them up for other projects (my garage refrigerator running on its own mini-system!!!)

Posted by tattoo

Aug 13, 2019 at 10:15am

mediadogg Avatar

Aug 13, 2019 at 8:36am mediadogg said:

I have not noticed that issue when I have used the ProWatt alone. But of course now, the two I have are being used along with the MOES. Today I just got my solid state relay to be used to toggle the MOES trigger line. If that works, I will be eliminating the ProWatt from the configuration to free them up for other projects (my garage refrigerator running on its own mini-system!!!)


I have been reading and keeping up with this thread and I was wondering the need for all of the special things you guys are using in your systems? ? ? ? Does it help it run better??


This is just a question.....

Posted by mediadogg

Aug 13, 2019 at 12:42pm

tattoo Avatar

Aug 13, 2019 at 10:15am tattoo said:

mediadogg Avatar

Aug 13, 2019 at 8:36am mediadogg said:

I have not noticed that issue when I have used the ProWatt alone. But of course now, the two I have are being used along with the MOES. Today I just got my solid state relay to be used to toggle the MOES trigger line. If that works, I will be eliminating the ProWatt from the configuration to free them up for other projects (my garage refrigerator running on its own mini-system!!!)


I have been reading and keeping up with this thread and I was wondering the need for all of the special things you guys are using in your systems? ? ? ? Does it help it run better??


This is just a question.....


Well I would ask what is the meaning of "better"? And then follow up with "better than what"?

My answers would be "better" = run the way I want it to, in order to meet my needs, and "better than what" = meeting my needs instead of not meeting them. Simple as that. No "right" or "wrong."

For example, as I was explaining before, I waste so much electricity on electronics and a big old house, that I can't afford to go "off grid" on a whole house basis. Just too expensive. Also, I like to tinker - "DIY." If I had one of those Solar City solutions, I would be bored out of my skull.

So, my mini-systems are affordable, do useful work (I got a check back from my power company last month), give me a chance to tinker, and with all the extra gizmos, they are almost "set and forget," so each day I generate some juice, day after day, without having to remember to turn something on or off.

Does that help to paint the picture?

Now if I were lucky enough to own a vacation cabin with good sun exposure, and energy usage in that cabin that would allow to go totally "off grid" with a traditional simple setup of PV > CC > Battery > Inverter > Load, I would gladly do it!!! At a minimum, I would still have a battery protection board, and maybe also a timer to prevent the inverter from running the battery down at night.

Posted by tattoo

Aug 13, 2019 at 1:29pm

mediadogg Avatar

Aug 13, 2019 at 12:42pm mediadogg said:

Well I would ask what is the meaning of "better"? And then follow up with "better than what"?



That's a good answer, I should have been clearer with my question.....


I guess better than a simple system like mine?  Without all of those switches and things like the MOES trigger line, ProWatt etc.... Or are they needed when your on the grid??


Like I said it's just a question trying to understand other peoples systems better.... Thanks

Posted by mediadogg

Aug 13, 2019 at 2:26pm

tattoo Avatar

Aug 13, 2019 at 1:29pm tattoo said:

mediadogg Avatar

Aug 13, 2019 at 12:42pm mediadogg said:

Well I would ask what is the meaning of "better"? And then follow up with "better than what"?



That's a good answer, I should have been clearer with my question.....


I guess better than a simple system like mine?  Without all of those switches and things like the MOES trigger line, ProWatt etc.... Or are they needed when your on the grid??


Like I said it's just a question trying to understand other peoples systems better.... Thanks


Right, if I get your question correctly. If you don't have enough power to be completely off grid, as you do, then you need some way to safely and reliably switch back and forth. I think that's basically it. Even though not totally off-grid, you get the satisfaction of knowing that at least you are doing as much as you can. Or you can go the expensive mickey-mouse of "grid-tied".

Posted by tattoo

Aug 13, 2019 at 2:45pm

mediadogg Avatar

Aug 13, 2019 at 2:26pm mediadogg said:

Right, if I get your question correctly. If you don't have enough power to be completely off grid, as you do, then you need some way to safely and reliably switch back and forth. I think that's basically it. Even though not totally off-grid, you get the satisfaction of knowing that at least you are doing as much as you can. Or you can go the expensive mickey-mouse of "grid-tied".


Yep that was my question...... So that's all those things do.....  That's good to know if I ever want to hook up to the grid.....


Thanks for your answers....

Posted by blade3609

Aug 13, 2019 at 2:57pm

mediadogg Avatar

Aug 13, 2019 at 8:36am mediadogg said:

blade3609 Avatar

Aug 13, 2019 at 7:58am blade3609 said:

when switching through the MOES the GFC tripped on trhe inverter right? not when making a switch on the PROwatt?


I have not noticed that issue when I have used the ProWatt alone. But of course now, the two I have are being used along with the MOES. Today I just got my solid state relay to be used to toggle the MOES trigger line. If that works, I will be eliminating the ProWatt from the configuration to free them up for other projects (my garage refrigerator running on its own mini-system!!!)


Which solid state relay did you buy? Did you also draw a diagram for that?



Posted by blade3609

Aug 13, 2019 at 3:00pm

blade3609 Avatar

Aug 13, 2019 at 2:57pm blade3609 said:

mediadogg Avatar

Aug 13, 2019 at 8:36am mediadogg said:

I have not noticed that issue when I have used the ProWatt alone. But of course now, the two I have are being used along with the MOES. Today I just got my solid state relay to be used to toggle the MOES trigger line. If that works, I will be eliminating the ProWatt from the configuration to free them up for other projects (my garage refrigerator running on its own mini-system!!!)


Which solid state relay did you buy? Did you also draw a diagram for that?




Yes my friend. My goal is to add more load when available during sunlight and move the load over the grid at night. Now i have 2x 200AH batteries , but those drain over night to 60 percent when using just about ~90 watts per hour at night. Batteries are expensive, and i don't want to plug more load manually each day during sun hours, need to automate this.

Posted by mediadogg

Aug 13, 2019 at 7:45pm

blade3609 Avatar

Aug 13, 2019 at 2:57pm blade3609 said:

mediadogg Avatar

Aug 13, 2019 at 8:36am mediadogg said:

I have not noticed that issue when I have used the ProWatt alone. But of course now, the two I have are being used along with the MOES. Today I just got my solid state relay to be used to toggle the MOES trigger line. If that works, I will be eliminating the ProWatt from the configuration to free them up for other projects (my garage refrigerator running on its own mini-system!!!)


Which solid state relay did you buy? Did you also draw a diagram for that?




Actually, I might be returning it. I was going to use it to cobble together my own way to turn off the trigger voltage to the MOES when there was no AC coming from the inverter. But then I remembered there was a cheap ready-made AC controlled relay that does this, and that I already had one sitting in the drawer waiting for this moment.  :DSo tomorrow, I will hook it up and see if / how it works, and whether eliminating the extra ATS affects how often the GFC trips. But that will take days of observation.

Posted by blade3609

Aug 13, 2019 at 8:31pm

Keep me posted buddie!



Posted by mediadogg

Aug 14, 2019 at 7:29am

blade3609 Avatar

Aug 13, 2019 at 8:31pm blade3609 said:

Keep me posted buddie!


Ok, the device seems to be working as expected. The MOES now does not get a positive trigger voltage when the inverter AC is off, no matter what the battery status is, and thus defaults to the grid. So I was able to remove the ProWatt from the configuration. Spent $14 to recover a $70 item. Good trade. Now it remains to run for awhile to see if the switching happens reliably, and whether the GFC still trips. If it does, my next step is to disconnect the inverter ground wire - right now, all three ground wires are tied together: inverter input+grid input+MOES output. Edit: scratch that idea. I just read several manuals from both Samlex and Renogy on grounding of the inverter. I absolutely do not want to disconnect the inverter ground wire from the MOES, unless I run the inverter chassis to an earth ground, which I don't plan to do. So, the inverter is by definition grounded when its ground is connected to another terminal that is in fact bonded to the earth. And certainly my grid AC input ground is very well grounded to the water pipe in my home, assuming nobody has screwed up in the wiring to my AC outlet.

My reading also confirmed that using low voltage disconnect circuits is a good thing, due to the complexity of determining the state of discharge of a battery under load. I know from experience that relying on the low voltage cutoff of the inverter can cause you to permanently damage your battery. By the time the inverter beeps or shuts off, your battery is already in serious trouble, and if it goes on too long, you will shorten the battery life. So, in answer to tattoo about all the gizmos, that is one I would recommend for any solar installation, even fully off-grid. Using one of those new LV disconnect circuits I referenced earlier, you can closely control how much stress you put on your battery, and keep it above 40% , 50% or whatever SOC you choose. Your own experience and environment will guide you how to choose the set points. And your battery will live to see many more cycles. 

Posted by blade3609

Aug 14, 2019 at 9:13pm

Do you have the diagram of how you wired that up exactly?

Posted by tattoo

Aug 15, 2019 at 3:09am

mediadogg Avatar

Aug 14, 2019 at 7:29am mediadogg said:

So, in answer to tattoo about all the gizmos, that is one I would recommend for any solar installation, even fully off-grid. Using one of those new LV disconnect circuits I referenced earlier, you can closely control how much stress you put on your battery, and keep it above 40% , 50% or whatever SOC you choose. Your own experience and environment will guide you how to choose the set points. And your battery will live to see many more cycles. 



That's some good info..... Thanks for posting that......


My batteries hardly ever are below 12.0 in the morning.... But that's at sag which is at start up of my fridge....... That's 12.2 at rest.... But by 11:00am at the latest my batteries are at 12.7 cloudy or not.....


Being off grid you can't really have something that will cut your system off unless there is a problem and it needs to be turned off......


I like my things in the fridge to be cold..... LOL


Thanks again...

Posted by mediadogg

Aug 15, 2019 at 5:12am

tattoo Avatar

Aug 15, 2019 at 3:09am tattoo said:

mediadogg Avatar

Aug 14, 2019 at 7:29am mediadogg said:

So, in answer to tattoo about all the gizmos, that is one I would recommend for any solar installation, even fully off-grid. Using one of those new LV disconnect circuits I referenced earlier, you can closely control how much stress you put on your battery, and keep it above 40% , 50% or whatever SOC you choose. Your own experience and environment will guide you how to choose the set points. And your battery will live to see many more cycles. 



That's some good info..... Thanks for posting that......


My batteries hardly ever are below 12.0 in the morning.... But that's at sag which is at start up of my fridge....... That's 12.2 at rest.... But by 11:00am at the latest my batteries are at 12.7 cloudy or not.....


Being off grid you can't really have something that will cut your system off unless there is a problem and it needs to be turned off......


I like my things in the fridge to be cold..... LOL


Thanks again...


Seems like your system has been well thought out, sized and configured for your needs!!

Posted by mediadogg

Aug 15, 2019 at 5:13am

blade3609 Avatar

Aug 14, 2019 at 9:13pm blade3609 said:

Do you have the diagram of how you wired that up exactly?


Working on it.

Posted by tattoo

Aug 15, 2019 at 6:51am

mediadogg Avatar

Aug 15, 2019 at 5:12am mediadogg said:

Seems like your system has been well thought out, sized and configured for your needs!!


Yep I tried..... So far so good...........

Posted by mediadogg

Aug 15, 2019 at 12:31pm

mediadogg Avatar

Aug 15, 2019 at 5:13am mediadogg said:

blade3609 Avatar

Aug 14, 2019 at 9:13pm blade3609 said:

Do you have the diagram of how you wired that up exactly?


Working on it.


OK, here is a system diagram. Hopefully I haven't made any gross errors. Please feel free to comment or ask questions. If I made a mistake, I can fix it. If I can improve my system based on your suggestions, that would be great!

Literally minutes ago, I just confirmed that it is on the switch back from solar to the grid, that the GFC trips. Otherwise, everything working as desired. No matter what the reason that the AC from the inverter is not present, the AC sensing switch causes the MOES to ignore the battery trigger voltage. Hence, the UPSs that power my equipment always get AC so long as the either the grid or solar is producing power.

Posted by mediadogg

Aug 16, 2019 at 5:45pm

Talked with Samlex engineer again today. He explained that such inverters, not designed to be connected to a home power panel, and its GFC will trip when it detects the neutral bonded to ground, which happens in the way I configured the MOES ATS. I suggested that naybe I should just disconnect the inverter ground wire, and he agreed. So, in the diagram I posted, all is the same except the grren wire from the inverter now floats. And so far, it has worked. Will see what happens tomorrow. By the way, this still allows the GFC to protect the inverter and the human from an internal short in the inverter. If the hot wire touches the chassis, the GFC will trip, probably before the internal fuses blow.

Posted by mediadogg

Aug 17, 2019 at 3:46pm

Another day of ATS cycles. No GFC trip. Cautiously hoping that I finally got it solved by not connecting the inverter ground  wire. Since the ATS is connected to a UPS, the loads are always grounded, even when being powered from the inverter. That's why the GFCI was tripping - it was seeing the neutral to ground bond of the house wiring being preserved by the UPS.

Posted by blade3609

Aug 20, 2019 at 5:30am

Good to hear mate! is it still good?

Posted by mediadogg

Aug 20, 2019 at 5:48am

blade3609 Avatar

Aug 20, 2019 at 5:30am blade3609 said:

Good to hear mate! is it still good?


Thanks, and yes no further trips since I detached the inverter ground from the configuration.

Posted by tattoo

Aug 20, 2019 at 6:58am

mediadogg Avatar

Aug 20, 2019 at 5:48am mediadogg said:

Thanks, and yes no further trips since I detached the inverter ground from the configuration.


That is really wild that a ground would cause that......... Glad you figured it out....

Posted by mediadogg

Aug 20, 2019 at 7:44am

tattoo Avatar

Aug 20, 2019 at 6:58am tattoo said:

mediadogg Avatar

Aug 20, 2019 at 5:48am mediadogg said:

Thanks, and yes no further trips since I detached the inverter ground from the configuration.


That is really wild that a ground would cause that......... Glad you figured it out....


Thank you. Yeah, the legacy design of that type of inverter did not consider they would interact with the grid in any way. They are made for standalone, and the GFCI correctly protects the standalone system. But I'm glad you reminded me ... I need to measure the potential difference between the inverter case / ground and grid ground. If there is any significant voltage there, I am at risk for touching the inverter case while in contact with mains ground. Bad news! If that turns out to be the so, I will have to scrap my design and get one of those "inverter / chargers," which have a built-in ATS and a modern design that uses relays to automatically take care of the neutral bonding conflicts (see page 14 here).
Edit: just checked, got about 5VAC. I will keep checking from time to time to make sure. But for now, seems OK.

Posted by blade3609

Aug 23, 2019 at 8:24am

Hows it going with the setup man ? still good? at what volt did you put the low switch and high switch?

Posted by mediadogg

Aug 24, 2019 at 11:10am

blade3609 Avatar

Aug 23, 2019 at 8:24am blade3609 said:

Hows it going with the setup man ? still good? at what volt did you put the low switch and high switch?


All good with both MOES units. Not at home now, and I don't recall the numbers, but they are different for the two installations because the loading, panels and sun patterns are different, so you will have to decide for yourself. I set the low point to be significantly above the battery protection board cutoff at maximum load, so that the inverter never beeps or shuts off (I think about 12.0 or 12.1), and I set the high point high enough so that the MOES is not flipping back and forth too often, but not so high that it never gets there on a cloudy day (I think about 12.8 on one system, but higher on the system that gets more sun).
  • Detailed Answer above

Login or Signup to post a comment