Ford Lightning as backup power

[JoeNorm]

Hi All,

I have a customer who wants to use his Truck as a backup to the already in place battery backup+solar.

Besides the Ford lighting stuff which I have not fully wrapped my head around yet, my question for now is how I could have two isolated systems(Lightning and solar+battery) feeding the same backed up loads panel? I would be OK with and actually prefer some manual transfer switching.

Thanks

 

[zbang]

Not knowing the Lightning specifically, but I don't see how you could have two sources, both of which assume they're the only one, feeding one load. If the solar/battery can operate in "line interactive" mode as if there were utility power (the Lightning), it might work. Then again, it might also let out the Magic Smoke. Definitely a place for proper transfer switches.

 

[retirede]

The Lightning has Ford’s “ProPower Onboard” which is simply a 7.2 KW portable generator with a bonded neutral. Treat it as you would any other such generator.

 

[GoldDigger]

The Lightning has Ford’s “ProPower Onboard” which is simply a 7.2 KW portable generator with a bonded neutral. Treat it as you would any other such generator.

Which means, among other things, that if the "generator" is stable enough to allow the interactive source to sync up under the UL-imposed anti-islanding requirements, there is another consideration in play:
A typical solar interactive system does not have any provision for limiting the amount of power delivered to the grid to less than is coming from the solar array at any moment. If the amount of solar power exceeds the local load at the time, the interactive source will try to push the excess power into the "grid", namely the generator. Inverters for this application require a system for regulating the output of the inverter based on external monitoring or commanding the inverter to shut down.
The other possibility, for the solar/battery system to operate as independent source, just delivering what the load requires, raises the alternate problem of synchronizing the two.

(This has no impact on how the ProPower system itself is wired, just how it can be used as part of a combined system.)

 

[jaggedben]

Put a manual transfer switch between the backup output of the existing system and the backed up subpanel. I guess you need a switch that switches the neutral. Don't overthink it.

 

[ggunn]

Put a manual transfer switch between the backup output of the existing system and the backed up subpanel. I guess you need a switch that switches the neutral. Don't overthink it.

Why would you need to switch the neutral?

 

[scrubbin]

From Reddit so take for what that is:
Normal transfer switches or inlet’ing directly to your panel through an interlock will not work. The Lightning’s outlets are neutral-bonded so the truck’s Pro Power outlets can function as a standalone jobsite generator… and the truck’s GFCI will detect the neutral-to-neutral or ground-to-ground loop and trip off when you connect it to another neutral-bonded system (like your house’s main panel). It has to be a neutral-switching transfer switch for GFCI generators, since they switch off one of the grounds or neutrals and breaking the loop, so the Pro Power doesn’t trip off. Reliance and Generac make them.

 

[GoldDigger]

Why would you need to switch the neutral?

From me and my interpretation of the NEC, for what it is worth: (see post from scrubbin, above)
If the truck source is wired as an SDS, with a bonded neutral, per retirede, but sharing the GES of the house, then Code does not allow you to have the truck, when plugged in, bond the GES to the neutral while the POCO/solar/battery GES to neutral bond is still in place. That will also cause problems with any GF detecting elements in the system.

 

[jaggedben]

Why would you need to switch the neutral?

Someone mentioned the neutral being bonded to the EGC at the truck and scrubbin confirmed what I was thinking.

From me and my interpretation of the NEC, for what it is worth: (see post from scrubbin, above)
If the truck source is wired as an SDS, with a bonded neutral, per retirede, but sharing the GES of the house, then Code does not allow you to have the truck, when plugged in, bond the GES to the neutral while the POCO/solar/battery GES to neutral bond is still in place. That will also cause problems with any GF detecting elements in the system.

Can you spell that out? I don't see it. I don't see any code section preventing a manual transfer switch between SDSs that are grounded in different locations. If the neutral is switched then I don't see an issue with GF detection elements. The one issue I do see is that the truck evidently doesn't meet the permissions in 250.34 to avoid being connected to the GES, and 250.30(A)(5) requires the GEC to be connected at the location of the system bonding jumper. If the system bonding jumper is inside the truck, then that is ... impractical, to say the least.

 

[brantmacga]

I installed a sub-panel at my brother’s house so he could feed essential loads from the 30A recep in his lightning, and it has been an ever loving nightmare to get working.

I interlocked a QO230 from the inlet and QO250SWN breaker as the sub panel main to isolate the neutral. The problem has been getting the lighting loads to not trip the GFCI in the Lightning. I’ve got all the recep circuits working (after finding a few receps where the ground was touching the neutral in the box), but he installed Lutron Caseta controls throughout his house, and they trip the GFCI every time. I’ve spent about 20 hours so far taking joints apart to find the loads that don’t trip it, but still haven’t figured out exactly what is causing it. I don’t know for sure yet if it’s the controls, or something in the fixtures.

He lives an hour away so it’s been tough to find time to get back over and continue troubleshooting. I would never attempt this install again.

 

[retirede]

I installed a sub-panel at my brother’s house so he could feed essential loads from the 30A recep in his lightning, and it has been an ever loving nightmare to get working.

I interlocked a QO230 from the inlet and QO250SWN breaker as the sub panel main to isolate the neutral. The problem has been getting the lighting loads to not trip the GFCI in the Lightning. I’ve got all the recep circuits working (after finding a few receps where the ground was touching the neutral in the box), but he installed Lutron Caseta controls throughout his house, and they trip the GFCI every time. I’ve spent about 20 hours so far taking joints apart to find the loads that don’t trip it, but still haven’t figured out exactly what is causing it. I don’t know for sure yet if it’s the controls, or something in the fixtures.

He lives an hour away so it’s been tough to find time to get back over and continue troubleshooting. I would never attempt this install again.

This is the Achilles heel of using the ProPower for backup. If you are feeding important loads on several branch circuits, it doesn’t take much leakage current on each circuit to add up to 5 ma.

 

[brantmacga]

This is the Achilles heel of using the ProPower for backup. If you are feeding important loads on several branch circuits, it doesn’t take much leakage current on each circuit to add up to 5 ma.

I’ve narrowed it down at least to only being two of the three lighting circuits I have in that panel. What I haven’t done yet is to remove all of the bulbs from the fixtures and start turning the switches on to see if it trips. It theoretically shouldn’t be those switches as they all have neutrals but idk for sure. I am fairly certain there are no shared neutrals between circuits as I wired the house, and I’ve opened every switch box again to verify. I’ve had two neighbors ask me to do the same install in their houses and I turned them down.

 

[JoeNorm]

I installed a sub-panel at my brother’s house so he could feed essential loads from the 30A recep in his lightning, and it has been an ever loving nightmare to get working.

I interlocked a QO230 from the inlet and QO250SWN breaker as the sub panel main to isolate the neutral. The problem has been getting the lighting loads to not trip the GFCI in the Lightning. I’ve got all the recep circuits working (after finding a few receps where the ground was touching the neutral in the box), but he installed Lutron Caseta controls throughout his house, and they trip the GFCI every time. I’ve spent about 20 hours so far taking joints apart to find the loads that don’t trip it, but still haven’t figured out exactly what is causing it. I don’t know for sure yet if it’s the controls, or something in the fixtures.

He lives an hour away so it’s been tough to find time to get back over and continue troubleshooting. I would never attempt this install again.

My customer wants to use a bidirectional charger and add an inverter for backup, I'm not sure were talking about the same thing?

 

[retirede]

My customer wants to use a bidirectional charger and add an inverter for backup, I'm not sure were talking about the same thing?

We’re not.
Currently, the only way to access the battery directly to power an inverter for backup power is to use Ford’s proprietary equipment supplied by SunRun.

 

[jaggedben]

My customer wants to use a bidirectional charger and add an inverter for backup,

(You didn't make that at all clear in your OP, especially since you mentioned preferring manual transfer equipment.)

You could possibly put the Ford/Sun Run equipment downstream of the existing battery backup. Or vice versa. So then you'd have nested backup systems. For example, grid fails, existing battery takes over; existing battery runs out of charge, then the Lightning takes over. It's a bit Rube Goldberg and more boxes on the wall than I'd like to have in my home. I think there's also potential problems either way you do it.

If you put the existing battery/solar upstream, the Ford/SunRun system won't know it's off grid, and the truck may charge and drain the existing batteries lickety split, assuming the existing system can even supply that power.
If you put the Ford/SunRun system upstream then the existing solar won't know it's off grid, and the solar may try to backfeed power to the Ford/SunRun system and that make not work and/or void a warranty.

If this is the sort of thing the customer really wants, I'm unaware of another way to do it at the moment. It would help if there were an open standard for bidirectional charging so that people aren't stuck with exclusionary systems for certain vehicles, but that may never happen.

 

[GoldDigger]

Someone mentioned the neutral being bonded to the EGC at the truck and scrubbin confirmed what I was thinking.



Can you spell that out? I don't see it. I don't see any code section preventing a manual transfer switch between SDSs that are grounded in different locations. If the neutral is switched then I don't see an issue with GF detection elements. The one issue I do see is that the truck evidently doesn't meet the permissions in 250.34 to avoid being connected to the GES, and 250.30(A)(5) requires the GEC to be connected at the location of the system bonding jumper. If the system bonding jumper is inside the truck, then that is ... impractical, to say the least.

My response was in answer to the question of why the neutral had to be switched.

 

[wwhitney]

You could possibly put the Ford/Sun Run equipment downstream of the existing battery backup. Or vice versa. So then you'd have nested backup systems.

Seems like that would work well as long as any initiation delays are coordinated. E.g. it would be annoying if each of the two back up systems waited exactly 1 second on loss of grid power before starting up, resulting in a race where sometimes the 2nd level backup initiates its own island before the 1st level backup kicks in, and sometimes it doesn't.

If you put the existing battery/solar upstream, the Ford/SunRun system won't know it's off grid, and the truck may charge and drain the existing batteries lickety split, assuming the existing system can even supply that power.
If you put the Ford/SunRun system upstream then the existing solar won't know it's off grid, and the solar may try to backfeed power to the Ford/SunRun system and that make not work and/or void a warranty.

Do you happen to know if the Ford/SunRun system does or does not support off-grid PV?

Cheers, Wayne

 

[jaggedben]

Seems like that would work well as long as any initiation delays are coordinated. E.g. it would be annoying if each of the two back up systems waited exactly 1 second on loss of grid power before starting up, resulting in a race where sometimes the 2nd level backup initiates its own island before the 1st level backup kicks in, and sometimes it doesn't.

That strikes me as probably less annoying than either of the other problems I mentioned.

Do you happen to know if the Ford/SunRun system does or does not support off-grid PV?

It appears to. EVSE, Battery, and PV are all DC to one inverter. I have not installed it though.

 

[wwhitney]

It appears to. EVSE, Battery, and PV are all DC to one inverter. I have not installed it though.

But for the nested solution, the question is whether the Ford/SunRun controller is designed to deal with AC coupled PV when off-grid, e.g. when necessary can it throttle AC coupled PV by raising the frequency?

If so, then nesting the systems as grid - Ford/SunRun - existing backup seems promising. Although then I guess there's the question of how the existing backup system would react to seeing a high frequency "grid".

Cheers, Wayne

 

[jaggedben]

But for the nested solution, the question is whether the Ford/SunRun controller is designed to deal with AC coupled PV when off-grid, e.g. when necessary can it throttle AC coupled PV by raising the frequency?

If so, then nesting the systems as grid - Ford/SunRun - existing backup seems promising.

Cheers, Wayne

Ok, right. In that case my guess is no, the Ford/Sunrun system likely doesn't support AC coupling with a third party solar. But I don't know for sure.