Plan: Off grid solar with a Model S battery pack at the heart

[AudubonB]

wk057: based on my experience, your inverters should work just fine without the software update (for your test - eventually you'll want to install it). I've never determined what the differences are from one software tweak to the next. Outback - like TM! - regularly updates its system. 'Cept they do it the old-fashioned way, as you know, through downloads from your computer thence via SD card, rather than the TeslaWay.

 

[wk057]

wk057: based on my experience, your inverters should work just fine without the software update (for your test - eventually you'll want to install it). I've never determined what the differences are from one software tweak to the next. Outback - like TM! - regularly updates its system. 'Cept they do it the old-fashioned way, as you know, through downloads from your computer thence via SD card, rather than the TeslaWay.

They refuse to operate with sync'd output if the firmware is mismatched. When I had the two setup with my test setup this happened and I had to update the one. I received the 8 in 4 different purchases, so, they could be on different versions.

---

So.... snags.

First, my 48V power supply is dead... so, can't use it for testing.

Second, I started working on the DC side copper bus bars so I could wire up the inverters. I rolled the roll of 4/0 cable I purchased ~month ago into my work area and removed the shrink wrap to find that it was not the flexible cable I had wanted... and it'll take a week or so to get the right cable. This will likely overlap with some travel plans, which means I'll have to wait until I get back to really continue. The wire I have is completely unmanageable with the turns in my conduit setup, plus is not really good for the connections since the wire will put torque on everything since it is so inflexible.

Probably all together looking at a 2-3 week delay on the project.

 

[FlasherZ]

Welding supply store? 4/0 is pretty hefty but you might be able to find it in stock there.

 

[AudubonB]

They refuse to operate with sync'd output if the firmware is mismatched. When I had the two setup with my test setup this happened and I had to update the one. I received the 8 in 4 different purchases, so, they could be on different versions.

---

So.... snags.

First, my 48V power supply is dead... so, can't use it for testing.

Second, I started working on the DC side copper bus bars so I could wire up the inverters. I rolled the roll of 4/0 cable I purchased ~month ago into my work area and removed the shrink wrap to find that it was not the flexible cable I had wanted... and it'll take a week or so to get the right cable. This will likely overlap with some travel plans, which means I'll have to wait until I get back to really continue. The wire I have is completely unmanageable with the turns in my conduit setup, plus is not really good for the connections since the wire will put torque on everything since it is so inflexible.

Probably all together looking at a 2-3 week delay on the project.

Ouch.
Doesn't the update go through that "buss-router" (to use an industry term, that black thingie with your HDMI cables) so that it would hit all your inverters at once? I'm a few thousand miles from my set-up, so I can't be more specific than that...but if so, at least all would be marching to the same drum right away.

Out of curiosity, is your 4/0 Cu or Al? I used micro-stranded welding cable, which is wonderfully limp, but in other uses have wrestled with gawdawful 4/0 Al, which is abhorrent....

 

[wk057]

Welding supply store?

Checked actually, and they have "Heavy duty welding cable." This would technically work, but I need flexible THHW or something with an NEC rating on the insulation for running it outside of the battery area, per NEC..... even though I could probably get away with the welding cable if I tried, I'd rather not have any issues with code.

I am using the flexible welding cable inside the battery area, though, since I interpret this as ebing allowed per NEC. 480.4 and 690.74(A).

690.74 Battery Interconnections.
(A) Flexible Cables. Flexible cables, as identified in Article 400, in sizes 2/0 AWG and larger shall be permitted within the battery enclosure from battery terminals to a nearby junction box where they shall be connected to an approved wiring method. Flexible battery cables shall also be permitted between batteries and cells within the battery enclosure. Such cables shall be listed for hard-service use and identified as moisture resistant.
Flexible, fine-stranded cables shall be terminated only with terminals, lugs, devices, or connectors in accordance with 110.14.

I guess it could be argued that my furthest inverter's load center is a "nearby junction box".

Anyway, I already ordered the #4/0 flexible THHW/TEW/MTW rated wire, which is code approved.

 

[wycolo]

@Theshadows:

A sticker like that was missing on the large solar array next to the Blanding, UT SpC that I inspected very closely while car was charging. Very good info to define an array. That was the only solar I've been at to date. It feeds the city grid only and has nothing to do with the supercharger. Seems about the right size to charge a Tesla or two off grid.

Was that 4in of fluffy snow or dense & wet? Amazing that you were seeing 42v thru anything like that. Still looking for clues about how it upshifted to effect charging of the 48v bank. Nice catch being there for that!
--

 

[TheTalkingMule]

This project is absolutely amazing, lets hope we can get Elon to chime in with his opinions once it's up and running. So annoying that TSLA being public limits what we can ask of the CEO and what he can comment on.

Question... When this thread first started I had assumed the non-battery hardware would be relatively simple, but now that it's progressing there are rows and rows of junction boxes, miles of conduit and it looks like a NASA lab or something. Can someone explain to the electrically illiterate why this setup requires so many different pieces of hardware seemingly in parallel? Is it to push charge out to the thousands of individual cells?

Thanks and again, amazing work you're doing here.

 

[FlasherZ]

Anyway, I already ordered the #4/0 flexible THHW/TEW/MTW rated wire, which is code approved.

Makes sense. Note that they want crimp lugs only, can't use set-screw or screw-based lugs with superfine cable.

 

[wk057]

This project is absolutely amazing, lets hope we can get Elon to chime in with his opinions once it's up and running. So annoying that TSLA being public limits what we can ask of the CEO and what he can comment on.

Question... When this thread first started I had assumed the non-battery hardware would be relatively simple, but now that it's progressing there are rows and rows of junction boxes, miles of conduit and it looks like a NASA lab or something. Can someone explain to the electrically illiterate why this setup requires so many different pieces of hardware seemingly in parallel? Is it to push charge out to the thousands of individual cells?

Thanks and again, amazing work you're doing here.

Well, the problem ended up being that no one seems to make an off-grid DC->AC inverter that can run from a high voltage DC input like the full pack produces. So, in an effort to actually make this project doable, I broke the pack down into pairs of modules instead of leaving the configured for high voltage. This brought my setup's nominal voltage down to the 40-50V range instead of 300-400V. 40-50V is usable input for off-the-shelf off-grid inverters. Unfortunately they're pretty low power and high amperage vs what a high voltage inverter would be capable of. So, I'm using 8 in parallel to get a max continuous possible output of 64kW. And yeah, it's a lot of wire.

The charge controllers (17 of them) will take my solar panel output and convert that to the proper voltage to charge the reconfigured low-voltage DC pack.

Makes sense. Note that they want crimp lugs only, can't use set-screw or screw-based lugs with superfine cable.

Yeah, I have lugs and a crimp tool. Should be fine.

 

[InTheShadows]

I was wondering how you were going to deal with that.

I was wondering if a regular solar inverter could be used with just placing the battery pack in the place of the solar inputs with a 15 amp fuse. So taking the 400v output from the battery pack and running it to the PV inputs. The fuse would protect everything (pack and inverter) if it doesn't work. I'm just not sure how the inverters mppt would react.

 

[Tedkidd]

Question... When this thread first started I had assumed the non-battery hardware would be relatively simple, but now that it's progressing there are rows and rows of junction boxes, miles of conduit and it looks like a NASA lab or something. Can someone explain to the electrically illiterate why this setup requires so many different pieces of hardware seemingly in parallel? Is it to push charge out to the thousands of individual cells?

Thanks and again, amazing work you're doing here.

So, I think part of this is the capacity. If I'm following correctly, he'll have enough capacity to EV charge 400 miles a day, run his house comfortably including heat pumps at outdoor temperatures from -40 to 120f, and host a welders reunion - even if the grid goes down for zombie apocalypse.

 

[wk057]

So, I think part of this is the capacity. If I'm following correctly, he'll have enough capacity to EV charge 400 miles a day, run his house comfortably including heat pumps at outdoor temperatures from -40 to 120f, and host a welders reunion - even if the grid goes down for zombie apocalypse.

Sounds about right

 

[FlasherZ]

Sounds about right

It's kinda like my orchard. It started with plans for 2-3 fruit trees for some great summer fruit. Then before you know it, you're buying 70 HP tractors, spraying equipment, bucket trucks, and all sorts of other stuff.

 

[Robert.Boston]

It's kinda like my orchard. It started with plans for 2-3 fruit trees for some great summer fruit. Then before you know it, you're buying 70 HP tractors, spraying equipment, bucket trucks, and all sorts of other stuff.

Isn't acquiring toys the whole purpose of a hobby?

 

[wk057]

Six more modules.

For about 15 minutes I had a P85D with 117kWh of battery power on board.

 

[FlasherZ]

Isn't acquiring toys the whole purpose of a hobby?

...until the hobby begins to snowball out of control.

 

[wk057]

...until the hobby begins to snowball out of control.

Snowball out of control? What?

Does 200kWh worth of Tesla batteries (up from 85kWh) and 64kW of inverters (up from 24 kW) and 102 solar panels (up from 66) count as snowballing out of control? lol

 

[FlasherZ]

Snowball out of control? What?

Does 200kWh worth of Tesla batteries (up from 85kWh) and 64kW of inverters (up from 24 kW) and 102 solar panels (up from 66) count as snowballing out of control? lol

Considering that 200 kWh would power my home, shop, car charging, orchard fruit coolers, and everything else at my home for over a day on the hottest day of the year?

 

[Robert.Boston]

Snowball out of control? What?

Does 200kWh worth of Tesla batteries (up from 85kWh) and 64kW of inverters (up from 24 kW) and 102 solar panels (up from 66) count as snowballing out of control? lol

Next you'll sign up your neighbors to be part of a microgrid. Hmm, that could actually be a really good idea, but I'll bet your utility wouldn't like it.

 

[wk057]

Next you'll sign up your neighbors to be part of a microgrid. Hmm, that could actually be a really good idea, but I'll bet your utility wouldn't like it.

The thought had crossed my mind. I'm sure during an extended outage there will be extension cords headed to my house from all directions to power neighbor's refrigerators and such. lol.