Converting to Powerwall 2 off grid

[Sodamo]

Coming from a personal lack of knowledge here, but
Thought it might be interesting if the generator could hook in like grid AC for emergency charging. Of course I'm assuming from what I've read that the PW is capable of charging from its grid source. Not all that different than car charging?

 

[miimura]

Coming from a personal lack of knowledge here, but
Thought it might be interesting if the generator could hook in like grid AC for emergency charging. Of course I'm assuming from what I've read that the PW is capable of charging from its grid source. Not all that different than car charging?

There is a big difference between the grid and a generator. You have to have a separate input to the system for a generator that powers a battery charger when you're off grid. Most generators are free running sources that don't sync to anything because they assume they are the only source of power. PowerWall 1.0 has to shut down and re-start in island (off-grid) mode when the grid goes down. It remains to be seen how PowerWall 2.0 will work as backup and off-grid.

 

[Sodamo]

There is a big difference between the grid and a generator. You have to have a separate input to the system for a generator that powers a battery charger when you're off grid. Most generators are free running sources that don't sync to anything because they assume they are the only source of power. PowerWall 1.0 has to shut down and re-start in island (off-grid) mode when the grid goes down. It remains to be seen how PowerWall 2.0 will work as backup and off-grid.

Interesting about the shutdown/restart. Hope they overcome that in PW2. Can't speak for all off grid systems but generator use with my Outback FX inverters is relatively seamless. I do have the option to run in Bypass mode, but in normal mode the generator can start on own and power is shared between the chargers and inverters powering the house. It's possible to program how many amps go to charger vs house loads. Not new tech, my inverters are 10 yo. Having a separate charger isn't a deal breaker, but built in would be more elegant solution.

 

[AudubonB]

Good luck Sodamo and I'll keep up on this to learn how it works out. Your overall system is similar in size to ours - you have more PV panels; we have a far larger battery bank. As it should be with our usage and latitude.

Q: Are you sure your inverters are 3048s? We use 8048s and I'm thinking you might have mis-typed.
Q: What are your generators, how often have you used them and is there a good reason you have two...or is it just because you didn't sell off the older one?

Miimura: the Mate3 that Sodamo has is well-capable of taking any input from a stand-alone genset and properly syncing everything. Once you CAT5 cable each of the inverters into the Mate3, it is superb at keeping everything running between 59.9 and 60.1 Hz no matter what.

If I trusted Li-ion batteries to stand up to the wicked cold, I might sell off our Absolyte IIPs and go with one single Powerpack, but I really can't be the first one to throw myself on that grenade. I'll go second.....

Speculation: the Powerwall2s will incorporate the appropriate charge controller. You may be able to bundle your batteries, inverter AND CCs all as one parcel to sell.

 

[Sodamo]

No typo, FX3048T x 4, the Radians weren't on the product list when I installed my system. Would have seriously looked at it if so as I was aiming to get a top of the line system at the time. My FX inverters are no longer available and should the PW2 not include the appropriate inverter and I opt that route then an inverter upgrade would be in my future. This past year I upgraded my MX60 charge controllers to FM80's. I like to keep the system from falling too fall behind and recover some of that cost reselling my still good equipment. I could probably have my current Outback stuff sold same day as PW2 gets installed.
I did check the FX install manual and it doesn't care if AC in is grid or generator, same terminals and then the appropriate programming in the Mate, whichever version. I did upgrade to Mate 3.

As for Generators... as said, we are completely off grid, so backup is nice.
I previously had a Ridgid 8500 as backup for my diesel. A couple years ago starter went out of diesel so Ridgid got some use. Shortly afterwards the Ridgid avr went out, warranty issue. Made the mistake of "upgrading" my diesel unit to one from Phoenix, AZ. Big mistake, but a separate story. So this spring, about 10 days before leaving on a 28 day trip the water pump went out on the diesel, no replacement part in the works. Ridgid back in service. Of course we had visiting dog/house sitters. The morning I'm getting on a 15 night cruise I get a text that generator is acting up. Oh, and it has been cloudy and rainy almost daily. Fortunately, I had a Honda 2000 ready to be connected and I told him how to connect and how to use to keep batteries up. He did lose power about 2 hours one night, but he didn't follow my instructions LOL. Once home, determined Ridgid isn't repairable, only producing about 45 hz. With another 27 day trip planned for Sep, I needed to get the system reliable, so primary repaired, secondary replaced with a 10kw MEP803a, military unit, both hooked into manual transfer switch and autostart controlled by Outback and monitorable via OpticsRE.

As for use. Unfortunately it is increasing. My Rolls Surettes are 10 years old and not keeping charge as well as before. So currently I have generator set for Must Run for 1 hour just before sun up. A couple reasons for this. My hot tub cycles on at 8 and has a 4kw heater, enough to autostart the gen if the right combo of low voltage/lack of morning sun. I like to avoid this as wife's washing machine and kitchen microwave hate this generator. Back in the days when my batteries were good and sunny days I would have to exercise the generator. If the PW2 works out I'd like to find optimal amount of PV to minimize running the generator. I don't think our weather would allow to go completely without a generator, but willing to be surprised.

 

[winfield100]

No typo, FX3048T x 4, the Radians weren't on the product list when I installed my system. Would have seriously looked at it if so as I was aiming to get a top of the line system at the time. My FX inverters are no longer available and should the PW2 not include the appropriate inverter and I opt that route then an inverter upgrade would be in my future. This past year I upgraded my MX60 charge controllers to FM80's. I like to keep the system from falling too fall behind and recover some of that cost reselling my still good equipment. I could probably have my current Outback stuff sold same day as PW2 gets installed.
I did check the FX install manual and it doesn't care if AC in is grid or generator, same terminals and then the appropriate programming in the Mate, whichever version. I did upgrade to Mate 3.
................
.

hokey smokes, i'm seriously impressed, nice system, nice life. paradise.
(can i visit just to take a look in next few years?)

 

[electracity]

There is a big difference between the grid and a generator. You have to have a separate input to the system for a generator that powers a battery charger when you're off grid. Most generators are free running sources that don't sync to anything because they assume they are the only source of power. PowerWall 1.0 has to shut down and re-start in island (off-grid) mode when the grid goes down. It remains to be seen how PowerWall 2.0 will work as backup and off-grid.

It is really the Solaredge inverter that needs to be disconnected and switched. As far as a generator, it will presumably always be on ab A/B switch: Choose either generator or mains.

I'm curious how Tesla will handle the DC side of multiple powerwall 2.

 

[Sodamo]

hokey smokes, i'm seriously impressed, nice system, nice life. paradise.
(can i visit just to take a look in next few years?)

We try
Not postcard Hawaii, but suits us.
Of course you can visit. Any forum member that books directly instead of VRBO will get a discount.

 

[miimura]

It is really the Solaredge inverter that needs to be disconnected and switched. As far as a generator, it will presumably always be on ab A/B switch: Choose either generator or mains.

I'm curious how Tesla will handle the DC side of multiple powerwall 2.

Systems that are designed to be off-grid usually have automatic generator start for when the batteries are low. The generator simply charges the batteries and does not directly power the loads - the main battery inverter does that.

 

[Sodamo]

Off grid with generator.
I really think a lot is dependent on your system. I'd have to say many don't have the autostart feature. I know that is very true locally.
In my first system, none of the solar components (Morningstar & Xantrax) had that function. My first two Generators were gasoline and could not be autostarted due to requiring the choke. Diesel generators often can be set up with a 2 wire start, but not all. My 1st diesel, the vendor insisted it could, but it took me nearly a year to figure out that the relay was 240vac and required it to sense grid failure to function, once I determined that and replaced with 12vdc relay it worked great. Even on the LP/NG side, not all are autostart capable and some that are are only capable if hooked to the grid and not conveniently modifiable to off grid.

 

[Sodamo]

Anyone seen any solid PW2 info since the announcement?

Is there anyway to determine who the local installer might be?

Any physical configuration info available? I preordered 4 PW2 and would like to look how to configure space wise. Side by side would take about 10ft, not my best choice. 2x2 stacked might be doable. Thinking some sort a rack would seem most efficient depending on space between but figuring 5.5 inches each = 20" and max 6" in between = 18" would be pretty nice depending on the hook ups.

 

[miimura]

I saw a picture posted on this forum with two back to back as a free standing pedestal. So, I think you, or the installer, could get pretty creative with it.

 

[Sodamo]

I'll have to look for that pic. Thanks

 

[miimura]

Found it.

Looks like three ganged up?

From here: https://teslamotorsclub.com/tmc/posts/1810553/

 

[nexsuperne101]

I too am running a 48V battery system, with 8KW of solar. As I understand it, the Powerwall 2 has a 320V-400V operating voltage, with its own 4KW pure sinewave inverter. This means that the input voltage from the solar has to be at least 400V to charge the batteries to 100%. My current configuration would have to be altered, as it is 74V peak on an MPPT, giving over 100A of current on a good sunny day. The other issue for the guys with generators is that you will now need a 3 phase 400V generator, tapped on 2 phases (cross phase is 400V, single is 230V. Ok for us in the UK, no good for the guys in America, where you use a 120/208V system.

I will watch this thread with interest, as my current set up is due for replacement in the next year. 20KWh is all I would need, as all the heating is from solar PV/thermal and wood burning stove.

 

[Sodamo]

Ahhhh, thank you.
I remember seeing that, but on my iPad looks like they are on their side. Closer look shows they are standing and somehow mounted together. Like it, even more space saving than I suggested. I'd like to raise off ground level and possibly attach to wall where my Outback is currently.

 

[Sodamo]

I too am running a 48V battery system, with 8KW of solar. As I understand it, the Powerwall 2 has a 320V-400V operating voltage, with its own 4KW pure sinewave inverter. This means that the input voltage from the solar has to be at least 400V to charge the batteries to 100%. My current configuration would have to be altered, as it is 74V peak on an MPPT, giving over 100A of current on a good sunny day. The other issue for the guys with generators is that you will now need a 3 phase 400V generator, tapped on 2 phases (cross phase is 400V, single is 230V. Ok for us in the UK, no good for the guys in America, where you use a 120/208V system.

I will watch this thread with interest, as my current set up is due for replacement in the next year. 20KWh is all I would need, as all the heating is from solar PV/thermal and wood burning stove.

Thanks
I suspect that on the PV side it could be as simple as rewiring my multiple 48v parallel strings into higher voltage series strings at the combiner box Currently have 22 strings I guess I either lose strings or add strings depending on values required/supported. Future adding would be my choice as I would prefer to relegate my generator to minimal usage.

Do you have a reference on the generator issue? My military surplus generator 10kw is easily selectable 1 or 3 phase 120/208. My larger 24kw generator not so and even if I could reconfigure the alternator I believe would only be 208. Personally not familiar with residential scale 400v 3 ph, but it would seem to me the opposite direction Musk wants to go.

As for the sinewave inverters, I'm curious how they might work together. If I get 4 PW2s that's 4 inverters. In my current system of 4 3kw inverters, they are stacked with auto transformer and are used according to demand. While I've never seen need for more than two I configured with 4 for future possible expansion and to use the chargers.
I do hope I hear something relatively soon as I'd prefer to make a decision before my current batteries die.

 

[Sodamo]

Well, I emailed a local installer who advertises Powerwall with PV install with hopes of gleaning a bit of info - nothing. Said to contact Tesla. No way to do that that I have found.
I did go back to the online app no/ordering page and there is a PV calculator I hadn't seen initially. Says I need another 4KW PV to be 100%. Of course I'd rather do myself instead of a paid installation. Guess I could wire into my existing configuration and just let them change it but it would be nice to know what string configuration is required.

 

[miimura]

Eventually there will be installation manuals for PowerWall 2.0, so you would be able to figure out the string configurations, etc.

 

[Sodamo]

LOL, unfortunately, I often suffer from "eventually impatience", especially when brainstorming a project. Somewhere, someone has this info now

I've about got the wife convinced to go ahead and add more panels sooner than later as whatever batteries would benefit. I'm sure she is leaning towards this as she has asked pointed 'how are you going to do...' type questions. A very good sign.