wiring details of ground-mount system w/ string inverter, plus generator backup

[RShackleford]

Thanks for chiming in ...

My understanding is most line side taps are done because of buss capacity issue. Either the calculation about the buss Amperage capacity or just no more room for an additional breaker. Clearly adding a breaker is simpler with no downtime or need to coordinate.

I'm not worried about the down time, esp. since trying to minimize that is something the bldg inspector is being proactive about. And yeah, my panel is pretty full. OTOH, when/if I implement the critical-loads subpanel (in my drawing), that'll free up lots of room.

I understand now. Those are a cost effective solution to the issue of power outages.

Well, the cost is low but I'm not sure how high the effective is; only works when the sun shines, and I've got shading issues, so maybe I'll get close to the 2kW 3-4 hours per sunny day, if I'm lucky. But in an extended outage, that should be enough to juice up the Leaf's battery a little (the Leaf then powering some critical loads).

My separate inverter is a way to provide some portable backup to my relatives in case of an emergency. In the process I discovered the capacity of the DC to DC converter that allows me to pull over 100 Amps at 12 volts that running 1500 Watts of power would require. I currently can connect the inverter with jumper cables to my 12v battery. Long term want to set up Anderson connectors to make it easier and safer. It is only intended to be used on an 120 volt extension cord and I have no plans to connect it to to an Generator input for a critical loads panel. In my case my critical load panel would require 240 volts anyway.

The Leaf's DC-to-DC is reputed to be able to source 135 amps (at 12vdc), but I decided to be conservative (and not risk damaging anything) by sticking with a 1kW inverter. It can power my fridge, the modem/router/phone, and a light circuit (LEDs, of course) in the living area (for a few days, I estimate).

Also, this is cute, it allows me to cook with gas. Our dual-fuel range (electric oven, gas cooktop) will not allow the gas to flow if there's no electricity. But it has a 3-wire connection, IOW a neutral in addition the the 240vac hots. So if I connect a that 120vac inverter to both poles, then the 240vac part of the range sees zero volts (and of course, it wouldn't have enough amperage to run the oven anyhow). But the 120vac circuits, running off one hot and the neutral, work fine and don't draw much juice; and they let all the "logic" work, so the gas flows ! Will still work when I install a real generator inlet, I just wire the 120vac "hot" to both hots at the connector.

You might be interested in this thread (https://mynissanleaf.com/viewtopic.php?f=37&t=13097), and I did something very similar: replaced the 12v battery hold-down with a custom connector which includes a big ANL fuse and an Anderson connector.

One issue I've run into, the inverter has a GFCI outlet and an undefeatable ground-neutral bond. When I connected it to the main panel (in a very ad-hoc way when I tested it), the GFCI saw the bond and tripped (apparently they will do this, even though the neutral and hot currents aren't necessarily unbalanced). So if I expect my critical-loads subpanel to work with the Leaf/inverter, I need to be able to switch the neutral, which is non-trivial; or spring big bucks for a real transfer switch.

[Ampster]

Talked to a fellow who consults on local installations and he says the AHJ is fine with line side taps. POCO guy wasn't thrilled, but mostly because it means I'm without power after they pull the meter and before I finish the wiring, get it inspected, and have them re-install the meter. The AHJ actually wanted to know if I was doing it this way, so that they can expedite that final inspection for me; so that's cool. Plus, it'll give me a chance to take my Leaf backup system for another test drive

My understanding is most line side taps are done because of buss capacity issue. Either the calculation about the buss Amperage capacity or just no more room for an additional breaker. Clearly adding a breaker is simpler with no downtime or need to coordinate.

I have the inverter, and the model is in my OP. It has that "secure power" supply thing; dunno how well it'll really work, but it's a good inverter, so I figured what the heck.

I understand now. Those are a cost effective solution to the issue of power outages.

Not quite following. You have a hybrid solar system, and have loose Leaf modules as the storage ? And, separately, you're doing the same thing with your Teslas as I'm doing with my Leaf ?

I made it more complicated than needed.My hybrid inverter is irrelevant for your purposes.
My separate inverter is a way to provide some portable backup to my relatives in case of an emergency. In the process I discovered the capacity of the DC to DC converter that allows me to pull over 100 Amps at 12 volts that running 1500 Watts of power would require. I currently can connect the inverte with jumper cables to my 12v battery. Long term want to set up Anderson connectors to make it easier and safer. It is only intended to be used on an 120 volt extension cord and I have no plans to connect it to to an Generator input for a critical loads panel. In my case my critical load panel would require 240 volts anyway.

[RShackleford]

One, the question about the line side tap.

Talked to a fellow who consults on local installations and he says the AHJ is fine with line side taps. POCO guy wasn't thrilled, but mostly because it means I'm without power after they pull the meter and before I finish the wiring, get it inspected, and have them re-install the meter. The AHJ actually wanted to know if I was doing it this way, so that they can expedite that final inspection for me; so that's cool. Plus, it'll give me a chance to take my Leaf backup system for another test drive

Two, I am not sure you have purchased an inverter yet and the question might be what type of back up source to use in the event of power outage.

I have the inverter, and the model is in my OP. It has that "secure power" supply thing; dunno how well it'll really work, but it's a good inverter, so I figured what the heck.

I am also intrigued with the comment that you have considered some way to access your Nissan Leaf battery. Even though I have a hybrid inverter, powered by Nissan Leaf modules I have assembled a 1500W inverter that I can connect to my 12 volt battery in either of my Teslas to provide emergency power to my daughter and/or my sister who live nearby and have been subject to some of the same public safety power outages recently.

Not quite following. You have a hybrid solar system, and have loose Leaf modules as the storage ? And, separately, you're doing the same thing with your Teslas as I'm doing with my Leaf ?

[Ampster]

.....
One thing that might help you to use shorter cable runs is by using the leapfrog wiring method shown below.
........

Just a shoutout to @littleharbor to say thanks for this trick. I have a similar situation and this will simplify my wiring.

[Ampster]

@RShackleford , Thanks for the link to this thread. I don't know why I didn't see it earlier. Now that the array issues are hashed out, I guess it is time to revisit this thread. It seems there are two issues that haven't been addressed. One, the question about the line side tap. Two, I am not sure you have purchased an inverter yet and the question might be what type of back up source to use in the event of power outage.
Do I have that right?

I am also intrigued with the comment that you have considered some way to access your Nissan Leaf battery. Even though I have a hybrid inverter, powered by Nissan Leaf modules I have assembled a 1500W inverter that I can connect to my 12 volt battery in either of my Teslas to provide emergency power to my daughter and/or my sister who live nearby and have been subject to some of the same public safety power outages recently.

[littleharbor]

Sounds like you could use any GTI then, being you are powering your critical loads with a generator What is "GTI" ?
Grid Tie Inverter.

I guess you could do that when the power goes out but then again you won't know when the power comes back on if using the secure power feature. I'm a bit confused about people bringing up not knowing the grid is back up; isn't this always an issue ? Also, since my non-critical loads will remain connected to the grid (per drawing in my OP), they will clue me in that the grid is back, right ?

The SMA Inverter will disconnect from the grid and won't requalify to the grid till the Secure Power feature is switched off. You are probably right about other non critical loads lighting back up when the grid comes back on. You will need to look for them being other loads are being powered by your generator and secure power feature.

Sorry about this non standard quote reply. Something is acting funny and I couldn't get the "Quote" feature to work.

[RShackleford]

No one has addressed the issue of how the inverter's AC output connects to my main panel. Some places I see that it is done via a breaker in the panel (as in my drawing), but I've also heard of it simply being spliced into the service-entry cables (from the meter to the main breaker).

I wonder if the breaker option has to do with some POCOs requiring a way to disconnect the inverter from the grid. I think mine does, but I think it has to be on the outside of the house; that's the box labeled "disconnect" in my drawing - I can't imagine the disconnect and the breaker would both be required.

[RShackleford]

Sounds like you could use any GTI then, being you are powering your critical loads with a generator

What is "GTI" ?

I guess you could do that when the power goes out but then again you won't know when the power comes back on if using the secure power feature.

I'm a bit confused about people bringing up not knowing the grid is back up; isn't this always an issue ?

Also, since my non-critical loads will remain connected to the grid (per drawing in my OP), they will clue me in that the grid is back, right ?

[RShackleford]

That what I've thought this whole time, and a pic of Dale would have been a great avatar.

Ok, you guys happy now ?

[sdold]

I just figured you were using The name Rusty Shackelford from the Hing of the hill cartoon series.

That what I've thought this whole time, and a pic of Dale would have been a great avatar.

[bcroe]

Pretty much all panels can be leapfrogged in Portrait orientation, not all panels work in Landscape though.

In my preferred landscape mounting, no way would the leads reach. So I alternated the direction
of the panels, so I would only need an extension jumper for every other panel. Bruce Roe

24ReSiSec.JPG

[littleharbor]

No, not really . I need to add a pic to my profile ...


Thanks.


Cool. If the panels' cables will reach two panels over. I gotta figure out how I'm going to arrange my two strings also.



Yep.


Not following. Referring to my drawing, let's say the poco goes out. I flip the interlock on the critical-loads subpanel, and attach the "generator" (more likely, a 1kW inverter connected to our Nissan Leaf with its 40kWh battery). So the critical loads are powered, but the other loads are still connected to the grid. When grid comes back, I'll see power in those loads.

Not really sure how the "secure power" will fit into this, just seems like a cool thing to have. Probably what happens is I use the Leaf's charging cord, during the day, to put juice from the secure power into its battery.

I just figured you were using The name Rusty Shackelford from the King of the hill cartoon series.


Pretty much all panels can be leapfrogged in Portrait orientation, not all panels work in Landscape though.

[littleharbor]

No, not really . I need to add a pic to my profile ...


Thanks.


Cool. If the panels' cables will reach two panels over. I gotta figure out how I'm going to arrange my two strings also.



Yep.


Not following. Referring to my drawing, let's say the poco goes out. I flip the interlock on the critical-loads subpanel, and attach the "generator" (more likely, a 1kW inverter connected to our Nissan Leaf with its 40kWh battery). So the critical loads are powered, but the other loads are still connected to the grid. When grid comes back, I'll see power in those loads.

Not really sure how the "secure power" will fit into this, just seems like a cool thing to have. Probably what happens is I use the Leaf's charging cord, during the day, to put juice from the secure power into its battery.

"Not following. Referring to my drawing, let's say the poco goes out. I flip the interlock on the critical-loads subpanel, and attach the "generator" (more likely, a 1kW inverter connected to our Nissan Leaf with its 40kWh battery). So the critical loads are powered, but the other loads are still connected to the grid. When grid comes back, I'll see power in those loads."

Sounds like you could use any GTI then, being you are powering your critical loads with a generator

.Not really sure how the "secure power" will fit into this, just seems like a cool thing to have. Probably what happens is I use the Leaf's charging cord, during the day, to put juice from the secure power into its battery.
[/QUOTE]
I guess you could do that when the power goes out but then again you won't know when the power comes back on if using the secure power feature. What if the outage is a relatively short one. All outages in this area are less than 15 minutes.

[RShackleford]

Rusty, it is Rusty, isn't it?

No, not really . I need to add a pic to my profile ...

As for the MC-4 connections, you can buy cables with the connectors on both ends. you simply buy the proper length cable to cover the total +ive and -ive length and cut the cable appropriately.

Thanks.

One thing that might help you to use shorter cable runs is by using the leapfrog wiring method shown below.

Cool. If the panels' cables will reach two panels over. I gotta figure out how I'm going to arrange my two strings also.

You do know the limitations of the secure power feature don't you?

Yep.

This feature needs to be turned on at the inverter and ALSO needs to be turned off, manually. If the power comes back on from the poco you won't know it until you turn off the secure power and the inverter requalifies the grid.

Not following. Referring to my drawing, let's say the poco goes out. I flip the interlock on the critical-loads subpanel, and attach the "generator" (more likely, a 1kW inverter connected to our Nissan Leaf with its 40kWh battery). So the critical loads are powered, but the other loads are still connected to the grid. When grid comes back, I'll see power in those loads.

Not really sure how the "secure power" will fit into this, just seems like a cool thing to have. Probably what happens is I use the Leaf's charging cord, during the day, to put juice from the secure power into its battery.

[littleharbor]

Rusty, it is Rusty, isn't it?
As for the MC-4 connections, you can buy cables with the connectors on both ends. you simply buy the proper length cable to cover the total +ive and -ive length and cut the cable appropriately.
One thing that might help you to use shorter cable runs is by using the leapfrog wiring method shown below.

You do know the limitations of the secure power feature don't you? One you are limited to 1500 or 2000 watts output, depends on inverter model. Of course if your solar array isn't producing that much power, ie; heavy cloud cover, early or late in the day or nighttime you get what you get/ This feature needs to be turned on at the inverter and ALSO needs to be turned off, manually. If the power comes back on from the poco you won't know it until you turn off the secure power and the inverter requalifies the grid.

Leapfrog wiring of series wired panels.jpg