Incorporating a Lightning into an existing PV system - without HIS

[world2steven]

For anyone who has a grid that doesn’t go down for days or weeks at a time, a Home Integration System doesn’t make sense, particularly those of us with solar and battery backup. It would be nice, however, to be able to use the Lightning’s battery in the event of an extended outage. Could this be accomplished with a manual transfer switch that would transfer the power source for a home grid from a hybrid inverter to a line connecting to the Lightning’s 240v port?

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[v2h8484]

That should work if the transfer switch is setup such that your solar/battery system is connected to the utility input side on the transfer switch.

 

[ridgebackpilot]

@world2steven Let us know if this idea works for you. I'm in the same position: I have a solar array and Tesla Powerwall batteries. So I don't really need to go to the expense of installing the Ford Home Integration System.

That said, the extended range battery pack is the equivalent of nearly 10 Tesla Powerwalls! So I'd like to find a way to connect my truck to my existing home backup system without installing a duplicate gateway.

 

[VTbuckeye]

Thinking through this/talking it out...so it won't be concise.


You could put a manual transfer switch between the grid feed and the generator (pro power) feed with the transfer switch in place before the Tesla gateway. Then you would need to put the powerwalls into storm watch (can you update the address in the Tesla app to somewhere that storm is active?) or your system may allow for grid charging. This would need to happen with solar off so that the system does not try to export to the truck (or if you have a do not export setting). Then the powerwalls can charge, but it needs to be limited to 7kw to not overload the truck's inverter.

This would be complicated and there are many ways for it to not work and possibly break expensive stuff in the house and truck.

I have rooftop solar with micro inverters and powerwalls and would love to be able to use the truck to charge the powerwalls (only necessary in the winter as our system is large enough to recharge the batteries even in overcast conditions March through October and if power is out long-term we can get a couple days out of the batteries).

I guess another alternative would be whole home backup with the powerwalls, but adding a neutral switching backup panel with some of the circuits. Then switch to the truck power for some circuits and keep using powerwalls for other circuits.

Those who know better can tell me how these ideas won't work.

 

[Fastnf]

Enphase has a video showing how to charge their batteries using an inverter generator which is basically what the propower is. In the video they disconnect the grid and connect the portable generator. The connection could esaily be done using a transfer switch. I am looking at using a three phase 200 amp transfer switch which will allow transferring two hots and the neutral (as opposed the three hots for three phase). These manual switch can be had for as low as $600.

Here is the video.

 

[Fastnf]

Here is a technical brief from Enphase providing the same information in detail

 

[VTbuckeye]

It is great that enphase is doing this, but if you already have a competitor's system/mixed system (enphase micros with Tesla powerwalls) I don't think that enphase can help you.

 

[world2steven]

@world2steven Let us know if this idea works for you. I'm in the same position: I have a solar array and Tesla Powerwall batteries. So I don't really need to go to the expense of installing the Ford Home Integration System.

That said, the extended range battery pack is the equivalent of nearly 10 Tesla Powerwalls! So I'd like to find a way to connect my truck to my existing home backup system without installing a duplicate gateway.

I am going to get this blessed by someone who knows what he is doing. But from what I've seen on this forum there doesn't appear to be any reason it shouldn't work. It would seem to be equivalent to just taking my inverter out of the picture and directly connecting the Lightning to a critical loads panel, which a bunch of people have already successfully accomplished.

 

[ridgebackpilot]

Thanks, @world2steven. It also occurred to me that I already have the equivalent of the automatic switch included in Ford's Home Integration System.

When I installed my Tesla Powerwall batteries, they came with a Tesla Gateway II, which is essentially the same kind of power management system. It manages incoming solar energy, charges the Powerwalls, and sends excess solar energy back to the grid. I should just be able to wire the Ford Charge Station Pro into my existing system, which will treat the truck as simply another source of power, like my solar inverter.

I'm hoping a knowledgeable electrician should be able to accomplish this, perhaps the same guys that installed my Tesla Powerwalls and gateway.

 

[ridgebackpilot]

I guess another alternative would be whole home backup with the powerwalls, but adding a neutral switching backup panel with some of the circuits. Then switch to the truck power for some circuits and keep using powerwalls for other circuits.

Those who know better can tell me how these ideas won't work.

Thanks, @VTbuckeye. My Tesla Powerwalls are already set up for whole-home backup. It occurs to me we may be overthinking this.

The Tesla Gateway II is already set up to sense incoming solar power from my rooftop array, converted to AC by the inverters. If I simply wire the Ford Charge Station Pro (or better yet, the truck's 240 volt ProPower outlet) into the same circuit as my solar array, the Tesla Gateway wouldn't necessarily know the difference, right? Wouldn't it sense incoming energy and treat it the same way whether it's coming from the solar inverter or the truck?

During the day, when the Gateway is receiving power from the solar array, I'd leave the truck unplugged. But at night, when there's no energy coming from the solar array, the truck could supply energy to the Gateway and power the house and/or charge the Powerwalls.

I'm going to ask the electrician who installed my Powerwalls and Gateway how this might work.

 

[VTbuckeye]

Thanks, @VTbuckeye. My Tesla Powerwalls are already set up for whole-home backup. It occurs to me we may be overthinking this.

The Tesla Gateway II is already set up to sense incoming solar power from my rooftop array, converted to AC by the inverters. If I simply wire the Ford Charge Station Pro (or better yet, the truck's 240 volt ProPower outlet) into the same circuit as my solar array, the Tesla Gateway wouldn't necessarily know the difference, right? Wouldn't it sense incoming energy and treat it the same way whether it's coming from the solar inverter or the truck?

During the day, when the Gateway is receiving power from the solar array, I'd leave the truck unplugged. But at night, when there's no energy coming from the solar array, the truck could supply energy to the Gateway and power the house and/or charge the Powerwalls.

I'm going to ask the electrician who installed my Powerwalls and Gateway how this might work.

It might be that easy, but the enphase micro inverters have to synchronize with the grid/battery and the truck is not going to do that. Unless the powerwall inverter synchronizes with the truck. How do we get the system to pull no more than 7kw from the truck (house + recharging the batteries).
Let us all know what your electrician says.

 

[ridgebackpilot]

It might be that easy, but the enphase micro inverters have to synchronize with the grid/battery and the truck is not going to do that. Unless the powerwall inverter synchronizes with the truck. How do we get the system to pull no more than 7kw from the truck (house + recharging the batteries).
Let us all know what your electrician says.

There's been a lot of chatter on this subject on the Tesla Motors Club Forum and elsewhere. As more Lightnings are sold, a lot of people are trying to figure out how to connect their trucks to their homes (V2H) and avoid purchasing expensive Tesla Powerwalls or similar dedicated backup batteries.

It's beginning to look as if there are two options for us:

A. Contract Sunrun (or another competent electrician) to install the Ford Charge Station Pro and all the hardware associated with Ford's Home Integration System. Even assuming the Charge Station Pro came with your truck, the cost for this option, including installation and hardware, could easily top $10K.

B. Treat the Lightning as if it was simply an external generator, supplying 240 volt/30 amp/7.2 kW power to your home. It appears the only hardware really needed for this option is a manual or automatic power transfer switch. Actually it could be as simple as installing a 30 amp generator inlet box like this one, which retails for $36 on Amazon, and wiring it into your home electrical panel. When the grid goes down and your Powerwalls are exhausted, you simply plug in an extension cord from the Lightning's 240 volt outlet, and you're good to go. Total cost including installation: Less than $500.

Most homes don't draw anywhere near 7 kW unless they're running electric appliances (e.g., air conditioners, baseboard heaters, electric dryer, or electric water heater). In my home, all those appliances use natural gas--we don't have central air conditioning. But even if the power draw exceeds the capacity of the Lightning, apparently the truck will simply shut down. So that shouldn't be a problem. What do you think? @Maquis @hturnerfamily, @tommolog, any comments based on your experience?

 

[Grumpy2]

One important step left out of:

Actually it could be as simple as installing a 30 amp generator inlet box like this one, which retails for $36 on Amazon, and wiring it into your home electrical panel.

Must have a transfer switch to be sure the Lightning power doesn't backfeed into the grid.

 

[Maquis]

I should just be able to wire the Ford Charge Station Pro into my existing system, which will treat the truck as simply another source of power, like my solar inverter.

Not sure exactly what you’re thinking here, but the CSP doesn’t have an inverter.

 

[ridgebackpilot]

Not sure exactly what you’re thinking here, but the CSP doesn’t have an inverter.

I stand corrected! I just purchased my 2022 Lightning Lariat, which came with the Charge Station Pro, so still learning the systems.

As I said above, however, wouldn't a better option be to forget installing the Home Integration System and treat the Lightning as if it was simply an external generator, supplying 240 volt/30 amp/7.2 kW power to your home? It appears the only hardware really needed for this option is a manual or automatic power transfer switch. Actually it could be as simple as installing a 30 amp generator inlet box like this one, which retails for $36 on Amazon, and wiring it into your home electrical panel. When the grid goes down and your Powerwalls are exhausted, you simply plug in an extension cord from the Lightning's 240 volt outlet, and you're good to go. Total cost including installation: Less than $500.

What am I missing here?

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