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Want to add separate DIY system to existing Tesla solar and Powerwalls. Where to connect?

Why would you use an additional Neurio when there are at least 3 empty CT channels in the Gateway 2 pictured in this thread? The only reason I can think of is that the distance exceeds normal CT wiring, which probably doesn't apply to this case. The reason the CTs are empty in this case is that the solar production is reported digitally by the Tesla inverter. Adding 3rd party solar would require CT metering to be logically added in the Gateway to the solar quantity reported by the Tesla inverter.
I had asked the same question but the tech said it was just easier. They were able to install the neurio on the main panel instead of having to run the wires through the conduit from the PW+.
 

miimura

Well-Known Member
Aug 21, 2013
7,373
7,355
Los Altos, CA
If you had a backup switch instead of GW2.
Ok, I went back and re-read this thread and I see where I went off track.

@wwhitney was pondering how to properly do PV Production Metering with a utility provided meter and a Powerwall+ and you (@Vines) answered regarding Tesla CT metering. Then @dailo interjected with Backup Switch +Neurio for Tesla solar measurement.

In the big picture, getting the solar measurement into the Tesla system so Powerwalls behave as expected has a couple solutions and is relatively easy. How to add solar when your utility requires production metering raises the complexity a bit.
 
Thank you everyone for your help on this matter! I had a closer look at the inverter and have discovered there's a Neurio on the right hand side, with a single CT connected (1 of 4 ports). The Generac branded CT is hiding on the left hand side.

Screen Shot 2022-03-19 at 1.52.00 PM.png


Here's the CT:

PXL_20220319_194605892.MP.jpg


My strings are connected in the top right pattern shown here "4 combined strings":

PXL_20220319_194851371_2.jpg


According to this sketch Tesla gave me this is how the strings are wired:
  • String 1 has 2 strings of 5 panels in parallel
  • String 2 has 2 strings of 7 panels in parallel
But that seems to contradict the label which says "Combined strings must have equal quantity of panels". Or am I misinterpreting this?

Panels are Q-Cell 340W (each have a max of 40V) - so the string of 7 has a voltage of 7 * 40V = 280V

IMG_20220127_114014 (1).jpg

Blue string faces south and the red string faces east. The West roof has pool solar on it, except the NW corner which Tesla were originally going to put 4 panels on but then changed their mind and moved them to the south roof on the day of install.
 
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I have just received PTO on an 8.16 kWh Tesla solar system with 2 powerwalls (see photos). I have whole home back up. However, PV isn't quite enough for my needs, one reason being that Tesla wouldn't entertain installing panels on a porch roof (which can definitely hold them). So, my brilliant idea is to put up 4 panels on there myself with micro inverters. The panels I've picked out are 440W so it would take total PV array size to just a hair under 10 kW. I may have room elsewhere for 3 more, which would take it to 11.2 kW.

I like DIY and am confident with regular electrics. However, I'm not clear where to connect the output from the micro inverters to. It seems like the logical place to do so is the "PV combiner panel", but that's actually the output from the Powerwalls, not directly the PV. I've also read here that the powerwall needs to be aware of all solar if it's to charge from them. I've no idea where the CTs are, I've looked and the only obvious ones are built into the backup gateway.

So I'm looking for your help and advice! I'd hire an electrician but sceptical I can find someone who understands Tesla ESS. This isn't really any different from someone who had an existing PV only system them installed a separate Tesla solar system with Powerwalls. So I know this is possible I just don't know how to do it. Wishing now that I'd got the number of the Tesla electrician who installed it in the first place.
I believe the output from Tesla PVs goes directly to the GW. So any new PVs would need to be connected to GW directly.

I have two service panels and a GW for each, but total three inverters power 2>1 and 1>1 configuration.

I myself am planning on adding more panels as the existing setup is only good during sunny days, and winter is only 3 months away.

Please let us know if you make a breakthrough as you’ve already purchased the miPVs
 
I believe the output from Tesla PVs goes directly to the GW. So any new PVs would need to be connected to GW directly.

I have two service panels and a GW for each, but total three inverters power 2>1 and 1>1 configuration.

I myself am planning on adding more panels as the existing setup is only good during sunny days, and winter is only 3 months away.

Please let us know if you make a breakthrough as you’ve already purchased the miPVs
I didn't make a breakthrough. It's still something I want to figure out but the added complication of the separate solar meter was another layer. I suspect if I just connect at the small breaker box marked "PV combiner panel" it will all work just fine, but it wouldn't show the additional production in the app and possibly might screw up the other numbers? Something I may look at again this coming winter once it's cooler outside. Too hot in Vegas right now to be messing around with panels outside!
 
I like the option of adding additional panels to the Tesla inverter. How are your stings connected to the inverter? Are any of your stings combined to more then one mppt.
Yeah, me too. This would absolutely be my preferred option but sadly I have 4 sets of strings, combined in pairs, so there's no spare capacity in the inverter. Annoyingly one pair of strings could actually be in series and if it were, that would leave me with one MPPT spare. But of course changing the configuration from Tesla's designs would likely cause warranty issues if later discovered.
 

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