Apologies if this is covered elsewhere...

[ggunn]

He said inverter, not grid-tied inverter. I would assume he means a battery inverter. The 18 K he mentions is probably a Signature Solar 18kPV inverter, which is an all-in-one inverter that can take 18 kW of solar input and has 12 kW of 120/240 VAC output.

Well, OK, but he never said that, and even so, I don't know why he would put it on a transfer switch in the manner he described; I don't think it will work the way he thinks it will. I get self-consumption, but I don't have any experience with Signature Solar; I will see what Google turns up.

 

[LarryFine]

I still want to now where he found such an ATS at that price!

The closest thing I could find said it wasn't to be used in the US or CAN.

 

[CoolWill]

I still want to now where he found such an ATS at that price!

The closest thing I could find said it wasn't to be used in the US or CAN.

I think this is the one he was talking about. The price and description match. https://www.amazon.com/Automatic-Tr...pcontext&ref_=fplfs&psc=1&smid=A37GDVPIINVQ03

 

[Fred B]

I have and grounded inverter and ground/neutral-bonded to and in a separate breaker then to a separate panel of breakers, 4/3 with ground between all. That is what it is and for good reasons.

From this final panel I want to go through a 200 amp Automatic Transfer Switch to the house main panel. I simply want to send the inverter power to power the main panel and when it stops sending power to the main panel and switch to the utility power. The amount of obfuscated information I have waded through to identify the switch is crazy. I would think I simply need a device that switches *all* wires from one to the other when it detects no power from the inverter side, so four wires in from the inverter, four wires in from the utility, and four wires back out to the main panel. I can't identify any reason why this cannot be done.

Simply switch from one power source to another when no voltage detected on one source.

So what is the device type name so I can go buy one? Thanks in advance.

So because this thread has been allowed to continue, there are several things you don't seem to understand related to your solar system.

1 a "simple" transfer switch will not work as you express you want it to work. Solar system is designed to shut off power transfer when it senses utility outage. (NEC requirement) This is a safety requirement is the same as a transfer switch for a generator is to protect the linemen from electrocution when a generator is separately operating. (The utility transformer will bump up power (typical residential 120/240) from the generator back to the Grid line voltage in the thousands of volts. The danger of improper back feed of a generator.)

2 a Solar system has a testing function to monitor Grid power and to synch the Solar power wave form or phase timing to that of the Grid for it to operate in parallel with the Grid. Whether it is single phase or three phase doesn't change this need. (Not an issue for a backup generator as it has no parallel grid operation. and a change in specific phase timing is not an issue)

3 Solar must have a means to be "informed" that 1. grid is down, 2. generator is on, 3. generator is off and 4. power being restored to the grid. This and the synchronizing functions are a more complicated than just throwing a switch.

4 the code has specific criteria related to limitations on such an installation as to capacity limits of both the solar and the generator.

Now typically in the past and on most, the solar to be remotely compatible it required a Battery backup and "IT" was the backup power or a Generator would operate and the solar was disconnected for the loads.
More recently one manufacturer that I know of has made such an interactive parallel operating solar/generator operation system. A propriety product of SolarEdge, But it is a total package and generally not adaptable to other systems or even it's own brand outside of a specific limited older models.

 

[Fred B]

The cost is $250 and two hours of simple labor @ $35/hr. so $350 maximum all in.

Your basic assumption of $35/hr. is just wrong unless the electrician is your employee. Even then you are forgetting the overhead related to an employee that can be near double the employee pay and an employer needs to make money from an employee not just break even, or why have an employee.

Really disgusted with cheap "can't you just" "the lights come on so what's the problem" mentality out there related to electrical work. We have many years of training and years of schooling and continuing education to be come qualified. And peoples lives are in our hands the same as a doctor if we are negligent in the performance of our jobs. Most "Real" Electricians are aware of this and their quality work shows such and deserving of appropriate compensation.

 

[CoolWill]

I read the OP again. He is not doing anything with grid tie. Best I can tell, he wants to power a breaker panel from an inverter... a battery inverter. Then, when that inverter stops producing power he wants an ATS to switch over to utility power.

Seems like it could be done very easily with a relay powered by the inverter.

 

[ggunn]

I read the OP again. He is not doing anything with grid tie. Best I can tell, he wants to power a breaker panel from an inverter... a battery inverter. Then, when that inverter stops producing power he wants an ATS to switch over to utility power.

But even if all that is true (he never mentioned batteries) the economics don't work very well. Grid power is far cheaper.

He said "I am powering the main panel from one source (inverter) or if that is supplying no power, from the other source (service). This is done on every single 18+ Kv solar installation." What is he saying, exactly? What he claims is certainly not true of "every single 18+ Kv solar installation", whatever "18+ Kv" means. I guess he means "18+ kW", but this just adds to my impression that he doesn't know what he is talking about.

 

[CoolWill]

But even if all that is true (he never mentioned batteries) the economics don't work very well. Grid power is far cheaper.

He said "I am powering the main panel from one source (inverter) or if that is supplying no power, from the other source (service). This is done on every single 18+ Kv solar installation." What is he saying, exactly? What he claims is certainly not true of "every single 18+ Kv solar installation", whatever "18+ Kv" means. I guess he means "18+ kW", but this just adds to my impression that he doesn't know what he is talking about.

I agree that his terminology could use a tune up. He didn't need to mention batteries because he said "inverter". To me, without the qualifier "PV" or "grid-tied" in front of it, that means a battery based inverter. Later when he said 18+It, confirmed it because that is ALMOST the same name as the Signature Solar 18Kpv battery based inverter that is very popular right now in residential off-grid systems.

This is how I read what he wants to do: Use a 18Kpv battery-based inverter to feed a panel through an ATS with utility as the backup source. Simple enough.

Here is the inverter I believe he is using: https://signaturesolar.com/eg4-18kpv-hybrid-inverter-all-in-one-solar-inverter-eg4-18kpv-12lv/

There is some amount of guess work reading between the lines, but if you look at it with this in mind, it's pretty clear.

 

[Peter Evans]

Perhaps I am misunderstanding you, but it seems to me that you are proposing to power a home with a PV inverter with no connection to the grid when the transfer switch connects the PV to the home, and you haven't mentioned batteries. Most inverters are designed to run grid tied and cannot run without the frequency and voltage reference from the grid, i.e., off grid, unless they are coupled with a battery bank. Residential PV systems are virtually all designed to run in parallel with the grid when the grid is available. But you know all that, right? I must not be understanding you.

When you say "18+ Kv", do you mean "18+ kW"? 18kW is bigger than most residential PV systems - most that I have designed, anyway. Specifically, what inverter make and model are you proposing to use?

OK, thread reopened so able to reply. This is part of the development of a whole house, 90% off-grid, solar panel/battery inverter package including everything but the electrician tying in the four wires to the main breaker at a fixed price.

Mistyped, it is indeed 18+kW. My question was not about inverter/inverter capacity, capability, or frequency, that is all good and tested as reliable, but about the switching mechanism code requirements or obscure electrical requirements related to L1, L2, N and G.

The inverter is bonded neutral to ground, so is the main panel, there can only be one point of bonding so it looks to me like switching all four eliminates any concern about whats happening with possible ground loops/paths.

The second problem is the absurd quotes for what is a simple switching mechanism to tie the solar to the main panel via an ATS.

The solution appears to need an ATS that switches all of these simultaneously and automatically and simply needs to be two sources of 4 poles in (L1, L2, N, and G (and maybe not ground, that is why the thread) connecting through an interlock to four poles out to a breaker panels. $250 retail at the most. This is an accurate cost estimate (BSc Operations Management and also BSc Mechanical Engineering) so I am trying to determine what gold-plated device must be hidden in these thousand+ dollar ATS units.

As a side note I see some of the retail ATS ranging from $730 to $2500 obfuscate this simple requirement for various reasons including related to the manufacturer cutting costs to the bare bones while driving the price up, hidden by hidden certification costs that most don't know. If you want to distribute the cost of the one time certification for a few thousand units it adds another $20. They sell tens of thousands of units worldwide yearly.

 

[Peter Evans]

1) There are power quality problems associated with a cloud when solely run on solar with nothing to offset the sudden dip in energy production. This can have a negative impact on equipment.

2) Make sure what ever you install is listed or you are going to have a miserable time with the insurance claim and inspector / utility.

3) Make sure you are consulting a licensed professional.

Looks like I needed to qualify who I am before asking a question. This is part of the development of a whole house, 90% off-grid, solar panel/battery inverter package including everything but the electrician tying in the four wires to the main breaker at a fixed price.

Thanks, it looks like the undisclosed (to electrical professionals) certification cost as the tool they are using to drive the cost up. I have no idea what you mean by insurance claim, both sides are fed off of breakers in fireproof NEMA rated boxes. and are on the outside of the house (California) though I guess if you installed it internally and structurally per code there could be some some minor smoke damage if you didn't use two sets of breakers for each input.

 

[Peter Evans]

Consider me unconvinced.

Without question? Good luck.

 

[suemarkp]

OK, thread reopened so able to reply. This is part of the development of a whole house, 90% off-grid, solar panel/battery inverter package including everything but the electrician tying in the four wires to the main breaker at a fixed price.

Mistyped, it is indeed 18+kW. My question was not about inverter/inverter capacity, capability, or frequency, that is all good and tested as reliable, but about the switching mechanism code requirements or obscure electrical requirements related to L1, L2, N and G.

The inverter is bonded neutral to ground, so is the main panel, there can only be one point of bonding so it looks to me like switching all four eliminates any concern about whats happening with possible ground loops/paths.

The second problem is the absurd quotes for what is a simple switching mechanism to tie the solar to the main panel via an ATS.

The solution appears to need an ATS that switches all of these simultaneously and automatically and simply needs to be two sources of 4 poles in (L1, L2, N, and G (and maybe not ground, that is why the thread) connecting through an interlock to four poles out to a breaker panels. $250 retail at the most. This is an accurate cost estimate (BSc Operations Management and also BSc Mechanical Engineering) so I am trying to determine what gold-plated device must be hidden in these thousand+ dollar ATS units.

As a side note I see some of the retail ATS ranging from $730 to $2500 obfuscate this simple requirement for various reasons including related to the manufacturer cutting costs to the bare bones while driving the price up, hidden by hidden certification costs that most don't know. If you want to distribute the cost of the one time certification for a few thousand units it adds another $20. They sell tens of thousands of units worldwide yearly.

I don't see the need for a 4 pole switch. That is what is making this expensive. It is not always correct there there be only one point of bonding (red highlighted text above). In a 400A service (two 200A panels off a 400A meter base), each 200A panel has a N-G bond. When you have a generator and a service, the generator could be bonded or not. If the generator is bonded, you need to switch the neutral in the transfer equipment. If it is not bonded (floating neutral), you don't switch the neutral and the service N-G bond still works to bond the generator (the bonding is just done at the service equipment instead of at the generator).

If this is residential 120/240V single phase system, and because the inverter is bonded, you probably need a 3 pole transfer switch so that L1, L2, and N get switched. A 3 pole switch is less common and more expensive than a 2 pole switch. A 4 pole switch is even less common and even more expensive as it would be for a 3 phase system where you also have to switch the neutral. The grounds can all be interconnected together. The equipment grounds don't normally carry current, so ground loops aren't an issue.

 

[suemarkp]

A line side transfer switch needs to be marked Suitable for Use as Service Equipment (not sure if this will be Line side or Load side). It also needs to be able to withstand the available fault current. These things drive up the cost. If your transfer unit has a 5KA withstand rating, that probably isn't enough. Depends on the size of your service and the length of the service conductors.

I too have been surprised at the cost of transfer equipment. It is all over the place and seem to be more expensive than it should be. That is why a $40 sliding interlock plate is favored by many instead of a $300 to $500 transfer switch. But these are manual transfer switches. Automatic transfer switches cost even more. It is what it is.

 

[jaggedben]

Looks like I needed to qualify who I am before asking a question. This is part of the development of a whole house, 90% off-grid, solar panel/battery inverter package including everything but the electrician tying in the four wires to the main breaker at a fixed price.

...

First of all, you don't switch ground. Ever. Your failure to understand this reflects a fundamental lack of understanding of bonding requirements in the NEC and standard electrical industry practice (and thus, I daresay, you're not qualifying who you are very well). It's not something that's done. Even if you switched a green wire, there would be no point because those wires would be required to connect to metal parts that stay bonded to each other.

You are putting together a package to sell? I think you are making poor choices. Nobody else that I know of switches the neutral for this sort of application. (That covers Enphase, Generac, Tesla, Solaredge, Sonnen, Sol-Ark, SMA, Outback, probably one or two others I've forgotten.) If you're really serious about what you're doing I think you could have inverters made without a neutral-to-ground bond and then you could use a cheaper ATS. And also, you probably wouldn't be asking in an online forum like this for someone to recommend an ATS.

 

[GoldDigger]

A critical necessary feature for a transfer switch that switches the neutral is the contact timing.
It must interrupt all ungrounded conductors before it interrupts the neutral and must make the alternate neutral connection before making any of the ungrounded connections. If this is not done, connected loads will be exposed temporarily to a "lost neutral' situation during the transfer. Electronics and other sensitive loads might be damaged.

 

[ggunn]

OK, thread reopened so able to reply. This is part of the development of a whole house, 90% off-grid, solar panel/battery inverter package including everything but the electrician tying in the four wires to the main breaker at a fixed price.

Mistyped, it is indeed 18+kW. My question was not about inverter/inverter capacity, capability, or frequency, that is all good and tested as reliable, but about the switching mechanism code requirements or obscure electrical requirements related to L1, L2, N and G.

The inverter is bonded neutral to ground, so is the main panel, there can only be one point of bonding so it looks to me like switching all four eliminates any concern about whats happening with possible ground loops/paths.

The second problem is the absurd quotes for what is a simple switching mechanism to tie the solar to the main panel via an ATS.

The solution appears to need an ATS that switches all of these simultaneously and automatically and simply needs to be two sources of 4 poles in (L1, L2, N, and G (and maybe not ground, that is why the thread) connecting through an interlock to four poles out to a breaker panels. $250 retail at the most. This is an accurate cost estimate (BSc Operations Management and also BSc Mechanical Engineering) so I am trying to determine what gold-plated device must be hidden in these thousand+ dollar ATS units.

As a side note I see some of the retail ATS ranging from $730 to $2500 obfuscate this simple requirement for various reasons including related to the manufacturer cutting costs to the bare bones while driving the price up, hidden by hidden certification costs that most don't know. If you want to distribute the cost of the one time certification for a few thousand units it adds another $20. They sell tens of thousands of units worldwide yearly.

Whatever. I hope it works out for you, but I have designed many hundreds of residential and commercial PV systems over the last 15 years and it's not something I have ever done or would ever do.

 

[gene6]

200 amp Automatic Transfer Switch to the house main panel.

He said inverter, not grid-tied inverter. I would assume he means a battery inverter. The 18 K he mentions is probably a Signature Solar 18kPV inverter, which is an all-in-one inverter that can take 18 kW of solar input and has 12 kW of 120/240 VAC output.

What is the calculated load on the 200A panel ? If its more than 12KW you can't use a ATS unless you have a listed article 750 EMS. You need a manual transfer switch or a 'critical loads' panel that the ATS can switch into.

 

[PWDickerson]

I think this is the one he was talking about. The price and description match. https://www.amazon.com/Automatic-Tr...pcontext&ref_=fplfs&psc=1&smid=A37GDVPIINVQ03

If the switch the OP is referring to is indeed the one linked here, that is yet another red flag. It is neither UL listed nor recognized, and the word "switch" is even misspelled on its label.

This whole thing looks like a train wreck to me. Seems like you are in over your head, and if so, I hope you figure that out before someone gets charged a bunch of money for something that will have to be re-done by a qualified firm.

Please provide the equipment model numbers you are considering, especially the inverter, and also a single line diagram. That will clear up much of the ambiguity.

Good equipment is expensive. Good solar designers/contractors are too. Get over it!

 

[LarryFine]

If the switch the OP is referring to is indeed the one linked here, that is yet another red flag. It is neither UL listed nor recognized, and the word "switch" is even misspelled on its label.

I didn't find anything about Wi-Fi or remote control.

 

[ggunn]

This whole thing looks like a train wreck to me. Seems like you are in over your head, and if so, I hope you figure that out before someone gets charged a bunch of money for something that will have to be re-done by a qualified firm.

This thread was reopened when the OP, whose occupation is shown merely as "Management", indicated to the mods that his management role is part of the PV industry. People in management do not necessarily know much of anything about the technology they are "managing". Whether they should is another discussion.