Using Lightning as a Generator

[ridgebackpilot]

I'm starting a new thread on this to seek advice and counsel on my situation.

Like others here, my home already has a solar PV array and three Tesla Powerwall batteries, managed by a Tesla Gateway. So installing Ford's Intelligent Backup Power system would be redundant.

However, I would like to find a way to use my Lightning as a source of backup power, in case a prolonged grid outage drains my Powerwall batteries and the solar array isn't able to recharge them. I need the Lightning to function in the same way a power generator would. 7.2 kW from the truck's 240 volt outlet is plenty to run my entire house. And the truck's extended range battery pack is the equivalent of nearly 10 Tesla Powerwall batteries!

I've seen all the installations posted here of manual transfer switches and 3-pole, double-throw safety switches to wire the truck's power into home electrical systems. But none of those will likely work for me due to the complexity of integrating them into my existing solar power system. Even if I could install them, the cost would be prohibitive.

After meeting with three different electricians, the one option I seem to have left is to replace my existing SolarEdge 7.6 kW inverter with a hybrid inverter such as the Sol-Ark 8K which is wired for generator input. Properly installed and integrated with my solar power system and backup batteries, that would allow me to use the Lightning as a source of power for the house and even to recharge the Powerwall batteries. I've heard Enphase, Sunny Island, and perhaps others are also working on similar hybrid inverter technology.

Has anyone installed one of these hybrid inverters and successfully connected their Lightning? Look forward to hearing from @world2steven, @eopiela, and others.

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[Henry Ford]

The problem I see with that is the same problem for any installation without a neutral switch, the generator in the Sol-Ark 8K wiring diagram bonds neutral and ground at the main panel. As soon as Pro Power senses return current on the ground it will trip the breaker.

There's no code compliant way to get around this. The non-code compliant way to do it is to pull the ground from the power inlet box. I wouldn't do this because I don't understand all of the risks associated with it. I've seen terms like "bolted hot ground fault" and decided it's not worth it.

 

[world2steven]

After meeting with three different electricians, the one option I seem to have left is to replace my existing SolarEdge 7.6 kW inverter with a hybrid inverter such as the Sol-Ark 8K which is wired for generator input.

Even if you don't need the capacity, you might want to look at the Sol Ark 15. It has three MPPTs, allowing input from three different types of PV panels. My system was installed in three increments over 20 years with three different panel types. Like the Sol-Ark 8K you are considering, my Sol Ark 12 has only 2 MPPTs. I am going to need to replace at least one of those panel strings to get down to two types (wattage?). One of those strings is currently AC-coupled to the Sol Ark generator port.

Has anyone installed one of these hybrid inverters and successfully connected their Lightning? Look forward to hearing from @world2steven, @eopiela, and others.

My solar installer is presently booking about 6 months out so I plan to meet with an electrician soon regarding the installation of one of the two options you mentioned or possibly just using a cable connector with the ground pin removed.

The Sol Ark *will* work with the Lightning on the Gen input so long as the Ground Pin is removed from the cable plug in from the truck.

For us, extended power outages are so rare, the reprogramming of the Sol Ark to switch back and forth from AC coupling to generator input may be an acceptable or even permanent solution. I will post whatever solution my electrician proposes and would appreciate anyone else considering this approach doing the same. Sol Ark seems interested in any solutions that will keep Ford happy.

Does anyone have a POC for Ford engineering to vet any proposed configurations? If Ford's accountants and lawyers will permit it, it would seem wise for Ford to move beyond its partnership with Sunrun. As I understand it, when the Ford/Sunrun HIS is running any legacy PV systems won't be? Ford has a potentially great ad campaign if it can open up the Lightning's vehicle-to-home capabilities: "A free truck AND home backup storage for what Tesla would charge for the equivalent 10 PowerWalls."

 

[TF1000]

Solaredge does make a backup interface that has (or will have) a generator input. No idea if it will have the same neutral and ground issues and if it will work with your specific inverter. https://knowledge-center.solaredge.com/sites/kc/files/se-backup-interface-datasheet-na.pdf

 

[world2steven]

The problem I see with that is the same problem for any installation without a neutral switch, the generator in the Sol-Ark 8K wiring diagram bonds neutral and ground at the main panel.

(I need to have a new handle - 'Not an electrician'.) Apparently it is not possible to place a "neutral switch" between the Pro Power outlet and the socket connecting it to the Sol Ark generator input? What does a neutral switch do?

 

[Bandit216]

Has anyone installed one of these hybrid inverters and successfully connected their Lightning? Look forward to hearing from @world2steven, @eopiela, and others.

Yes, I have a grid-tied solar array with a hybrid Schneider inverter and controller, an LFP backup battery, and a 30A generator input that can be used to recharge the battery in the case of an extended outage. (The key to a system like this is that you will already have your critical circuits on a separate subpanel, so that you will not exceed the 30A output of the Lightning's Pro Power outlet in the bed.) The LFP battery backup option with the solar works great, by itself, for 2-6 hour outages (which are fairly common here). It is, however, a bit of a pain during extended outages when solar recharging is not available - especially if it's -40F and you are trying to start a cold-soaked generator.

My backup solution fits exactly what you are describing. To make it work without even having to go outside in the cold, I installed a 30A extension circuit that runs from an L15-30P outlet box inside my garage (Remember this is an input circuit that is always unpowered UNTIL it is plugged into the Lightning so the plug you see there isn't hot.)

to an L15-30R outlet next to the 30A generator input (L15-30P) on the deck. (Yes, you do need to disconnect the ground on the deck outlet to prevent the Lightning Pro Power from faulting.)

Normally, I always keep the garage output cord connected to the generator input. That saves me from having to go outside during an extended power outage. It also keeps debris, spider webs, etc. from getting in the outlets.

If the power goes out, my critical circuits are automatically powered for 2-6 hours by the LFP battery tied to the inverter,. If there is no (or too little) solar recharging, and my LFP battery starts to get low, I only need to manually turn on the 30A Pro Power outlet in the bed and plug in the 30A extension cable on the interior garage wall. Presto, the inverter see the Lightning's input power and treats it like the generator that it is. The image below is from the Schneider App with the Lightning providing power to the inverter. (The running time is blank because I did the screen capture before 1 minute had elapsed.)

If the power outage goes on for days (and the solar darkness continues) and the Lightning's battery gets low, you simply start your generator, unplug the extension cable from the garage output outlet on the deck then plug it into the generator's 30A L15-30R outlet. (If your generator fuel runs out, just accept that you are going to die - OR before running out of generator fuel, drive the Lightning to a charger with power, charge it up, then return home and start over.)

If your Lightning is parked close to your generator input, you may not need to install the 30A extension circuit I installed between my garage and the generator input on my deck. A simple pass thru port in your garage wall for an extension cord may work. I do prefer the added safety of a hard wired circuit as opposed to an extension cord laying on the ground.

Although I'm not familiar with hybrid inverter brands you are considering I don't see any reason it wouldn't work so long as your inverter's generator input circuit is designed for a 30A input - the max the Lightning's Pro Power can provide.

 

[ridgebackpilot]

Solaredge does make a backup interface that has (or will have) a generator input. No idea if it will have the same neutral and ground issues and if it will work with your specific inverter. https://knowledge-center.solaredge.com/sites/kc/files/se-backup-interface-datasheet-na.pdf

Thanks! But in my case, the Tesla Gateway 2 acts as a backup interface, and manages the charging of my three Powerwall batteries.

The Gateway detects a grid outage and switches over to the Powerwalls to provide backup power to the house. The Gateway also manages charging of the Powerwalls using energy from my solar array, even while the grid is down.

Tesla's documentation says the Gateway is compatible with a generator operated through an automatic or manual transfer switch. I'm going to ask my solar contractor who installed the Powerwalls about integrating a generator into the system.

If I can't integrate a generator (read Lightning) into my existing SolarEdge inverter/Tesla Gateway system, then I suppose I could install a Sol-Ark hybrid inverter, which should replace both my inverter and Gateway...

 

[dothedew]

Is your system wired such that the entire house is backed up by the powerwalls? Or do you have subpanel for critical loads?

 

[ridgebackpilot]

Is your system wired such that the entire house is backed up by the powerwalls? Or do you have subpanel for critical loads?

The Powerwalls back up my entire house; I don't have or need a critical loads panel. Several of my major appliances are powered by natural gas, including wall heater, clothes dryer, water heater, and oven/range.

As a result, I seldom draw more than 5 kW unless I'm charging my EVs, which I don't do during peak grid hours (3 pm-midnight) or a grid outage. So the Lightning's 7.2 kW output is more than enough to back up my entire house.

 

[dothedew]

The Powerwalls back up my entire house; I don't have or need a critical loads panel. Several of my major appliances are powered by natural gas, including wall heater, clothes dryer, water heater, and oven/range.

As a result, I seldom draw more than 5 kW unless I'm charging my EVs, which I don't do during peak grid hours (3 pm-midnight) or a grid outage. So the Lightning's 7.2 kW output is more than enough to back up my entire house.

How many times have you fully exhausted the power walls to the extent that they don't recover with the next days solar? This scenario just seems unfathomable to me that such complexity and investment is truly worth it.

 

[ridgebackpilot]

How many times have you fully exhausted the power walls to the extent that they don't recover with the next days solar? This scenario just seems unfathomable to me that such complexity and investment is truly worth it.

Here's the scenario: During an extended grid outage, the Powerwalls become exhausted and stormy weather severely limits solar generation to recharge them. That's when I'd want the Lightning (or a generator) to back up the Powerwalls.

You're right, it's a remote possibility where I live. So installing a transfer switch and hybrid inverter might not be worth the trouble and expense. But for others (like @Bandit216) who live in places like Alaska or the northern tier states where sunshine is less common and snow covers solar panels, the need for generator/Lightning backup might be greater.

In any event, it just doesn't make sense to me to have an enormous source of power sitting in my driveway but unable to back up my house when needed. To tell you the truth, had the Lightning been available several years ago when I first installed my Powerwalls, I might have gone with the Ford Intelligent Home Backup system instead!

 

[Henry Ford]

(I need to have a new handle - 'Not an electrician'.) Apparently it is not possible to place a "neutral switch" between the Pro Power outlet and the socket connecting it to the Sol Ark generator input? What does a neutral switch do?

A neutral switch removes the neutral/ground bond in the main panel and allows the neutrals - in whatever circuits you choose - to be bonded on the generator. This is necessary to prevent the truck's GFCI from tripping.

A neutral switching manual transfer switch can be thought of as a sub-panel. With the caveat that I haven't thought very hard about it, I don't see any reason you couldn't integrate one into any system.

An actual electrician could better explain your options. I only know enough to not burn my house down.

 

[eopiela]

@Bandit216 did an excellent job of showing (with pictures) a similar system to mine. When my house was built (after Winter Storm 2021), we had 50A generator inlets for each panel (which are separate 200a feeds from my 400a service meter, not a sub panel). I bought two generators and was happy. After fumbling around in the cold one time in 2022, I began to search for a battery backup. I installed the Sol-Ark 15k between the meter and the main panel for the house and had the electrician install generator inlets inside my garage (knowing I had the lightning on order). One goes to the generator inlet of the the sol-ark, and the other is a pass-through also connected to the gen inlet for the second panel. This allows me to run both panels off the sol-ark, with a 14-50 to gen cable between them, or plug the truck into either the sol-ark or the second panel (which has my heat pump compressors) to divert load to the truck and save conversion losses (DC-AC-DC-AC vs DC-AC). You want to go with the Sol-Ark 15k as another poster mentioned as it is the only one with the 200a grid pass through--without that you have essentially limited your house to running off a single 50A breaker. While your load might survive that now, think about your future loads.

 

[roddiaz1]

This past weekend we lost power for several days, so the Lightning came in real handy keeping the refrigerators running so the food wouldn't spoil. I used the uber-basic and crude extension cord method of powering my house during the black out.

On day two, the water pressure finally went to zero, despite our conservation and we all wanted to take showers, so I decided to hot-wire the well pump (240V 30AMP) directly from the Lightnings 30Amp 240V plug (in the bed). My pump has a junction box (where I can disconnect from the main panel).

The problem was that I had a four-wire extension cord (B,R,W,G) and the pump has a three wire set-up (B,W, bare copper), so I had no choice but to "bond" the neutral and the ground at the junction box. I literally had both on the same screw/lug in the junction box. Wouldn't you know, it worked! The Lightning didn't flinch. It powered the well pump for several hours even though it was "bonded".

I'm definitely not an electrician, so I can't explain why, but it worked.

 

[Maquis]

This past weekend we lost power for several days, so the Lightning came in real handy keeping the refrigerators running so the food wouldn't spoil. I used the uber-basic and crude extension cord method of powering my house during the black out.

On day two, the water pressure finally went to zero, despite our conservation and we all wanted to take showers, so I decided to hot-wire the well pump (240V 30AMP) directly from the Lightnings 30Amp 240V plug (in the bed). My pump has a junction box (where I can disconnect from the main panel).

The problem was that I had a four-wire extension cord (B,R,W,G) and the pump has a three wire set-up (B,W, bare copper), so I had no choice but to "bond" the neutral and the ground at the junction box. I literally had both on the same screw/lug in the junction box. Wouldn't you know, it worked! The Lightning didn't flinch. It powered the well pump for several hours even though it was "bonded".

I'm definitely not an electrician, so I can't explain why, but it worked.

Your pump doesn’t require a neutral. You could have run just 3 wires to the pump (L1, L2, and ground), no neutral.

The reason it worked the way you did it is since the pump doesn’t have a neutral, there was no neutral current to travel on the ground, so no GFCI trip. That is a bit oversimplified, but hopefully it makes sense.

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