Maybe true, but I am putting lots of pieces together, and doing the math. I have no concern now that my PW's can put out 7.5kw increase power capacity and not trip the 30 amp breakers. This only happens for a few seconds, when a AC starts us. Or do you have math that is different than Whittneys?
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Discussion: "Powerwall +"
- Thread starter willow_hiller
- Start date
No, I am just replying to the statements you keep making regarding what the call center employees say. Several times you have said "thats not what they are telling me". Thats the only thing I was replying to.
pdx_m3s
Active Member
Here's Tesla's "New Construction Pre-Wire Guidance" that they provided to me last year last year when I did my new-construction solar. It would appear that the PW+ solar module combines the inverter and the generation panel. Could it also combine the gateway as well?
I like to think graphically....
I like to think graphically....
They have just been one piece of the pie. Doing the math, and having folks here verify, shows me its a non issue, which is different than my first thoughts. The support folks have just said nothing to say it will not happen. The last even got off phone and verified with her managers. We shall see I guess soon who is right.
Yes, at least in the picture on the spec sheet, which would apply for 1 PW and solar not exceeding what the solar module can handle. The disconnect function of the Gateway must be in the meter adapter shown in the picture. The rest of the functions of the Gateway must be in the solar module on top of the PW.
Cheers, Wayne
pdx_m3s
Active Member
The PV module has higher current per MPPT (13A) compared to the 7.6kW Tesla PV inverter (11A). This would put it closer to an 11kW inverter, right?
If it does, then when the PW is full, it will be throttling the PV production, as it can only export 7.68 kW when the grid is present, per the spec sheet.
Cheers, Wayne
pdx_m3s
Active Member
Interesting. Perhaps the inverter is the same size, but it is just capable of accepting a higher power PV array (more over-driven).
dhanson865
Well-Known Member
When I go to https://www.tesla.com/energy/design each powerwall is about $5,000 more.
It shows me very limited coverage for 1 powerwall (and won't let me choose 1 powerall if my array is 12.x KW)
If shows me limited coverage for 2 powerwalls on 8.x KW array or full coverage on 2 powerwalls and a 12.x KW array.
On the 2 powerwall 8.x KW config and some 2 powerwall 12.x KW configs (depending on the monthly electric bill I input) it's not covering my water heater or dryer, but is covering everything else.
All of this still looks the same as it has been for the last few years. I would expect Powerwall+ to change the dividing lines here a bit. Maybe the website will update in a few weeks.
If I could get all my elecrtic on 2 poweralls no matter what that's a significant cost decrease for me as a customer not having to get that 3rd powerwall. If I can somehow shoehorn in the practial majority of my electric on a single Powerwall+ it could be even cheaper than the old 2 powerwall config that gave me partial backup.
It shows me very limited coverage for 1 powerwall (and won't let me choose 1 powerall if my array is 12.x KW)
If shows me limited coverage for 2 powerwalls on 8.x KW array or full coverage on 2 powerwalls and a 12.x KW array.
On the 2 powerwall 8.x KW config and some 2 powerwall 12.x KW configs (depending on the monthly electric bill I input) it's not covering my water heater or dryer, but is covering everything else.
All of this still looks the same as it has been for the last few years. I would expect Powerwall+ to change the dividing lines here a bit. Maybe the website will update in a few weeks.
If I could get all my elecrtic on 2 poweralls no matter what that's a significant cost decrease for me as a customer not having to get that 3rd powerwall. If I can somehow shoehorn in the practial majority of my electric on a single Powerwall+ it could be even cheaper than the old 2 powerwall config that gave me partial backup.
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I believe the solar inverter and Powerwall inverter are still separate. Therefore, grid connected Powerwall discharge of 7.68kW does not apply to solar production exceeding that value. When the grid is down, the solar would have to be curtailed in order for one Powerwall to keep charging at higher solar insolation levels.
My reading of the spec sheet is that both the Powerwall inverter and the solar inverter (if separate, as I would guess) share a single connection to the main panel/rest of the electrical system, and that connection is limited to 32A continuous while the grid is up.
Cheers, Wayne
But it seems clear to me that is what the spec sheet says.
And if Tesla, based on its installation experience, has found that dealing with NEC interconnection rules and panel changes has been one of their biggest headaches, a design that allowed the use of the 120% rule in a 200A main panel may be a rational choice. Given that the Powerwall can serve as a buffer to time shift production.
It may be that PowerWall+ is intended as a simplified solution for a majority of installs, and that more complicated topologies are still possible using Gateway2 with separate PowerWalls.
Cheers, Wayne
My pending install (mid May) is combining two solar systems (new +old) with 3 PWs. I want both systems to fully function when grid goes down, which I’ve been told by Tesla will be the set up.
it sounds like PW 2 (not +) is more conducive (or even crucial) to this dual solar set up? Maybe nobody knows quite yet with limited info.
my spec sheet still indicates PW2 but just asking before I start pushing them for the + model.
it sounds like PW 2 (not +) is more conducive (or even crucial) to this dual solar set up? Maybe nobody knows quite yet with limited info.
my spec sheet still indicates PW2 but just asking before I start pushing them for the + model.
The specs I've seen has the existing Tesla inverter at 13A per MPPT. Since there are 4 MPPT channels, and there are 12 panels = ~400V in a typical Tesla installation, that's 5.2kW per channel. So you can see that it isn't appropriate to add up the maximum current capacity in the MPPT channels to get the AC output capability. I guess that a modern inverter has a DC to DC converter on each MPPT channel, and the outputs of the up to 4 channels are added together as an input to the 60Hz inverter circuitry. In many installations there are arrays facing in disparate directions, and in others there are fewer than 12 panels per array. Solar roofs are something else again. The MPPT individual channels need to have a greater current capability than would be needed to reach the inverter power limitation. We can't plan on optimal solar power generation on each channel.
Well, its a good thing we have all these people who know what's going on. Looking at my install, there is really only one way to do it. Solar to Inverters to Gateway. Powerwalls to Gateway. Grid to Gateway. Gateway out to backed up loads, which in my case is everything.
It has to be this way because the Gateway has to function with any one or two of the three power sources out. The only way for that to happen is if the Gateway is, well the gateway.
Combining the inverter(s) and the Gateway into one box and putting it on top of the Powerwall looks good and simplifies the installation a bit, but the basic wiring would have to be the same, just with one less box..
I think.
It has to be this way because the Gateway has to function with any one or two of the three power sources out. The only way for that to happen is if the Gateway is, well the gateway.
Combining the inverter(s) and the Gateway into one box and putting it on top of the Powerwall looks good and simplifies the installation a bit, but the basic wiring would have to be the same, just with one less box..
I think.
It makes sense to me. The solar can be a DCDC PPT buck converter to the battery rail with a single inverter from the battery to the mains. That lines up with the 60V minimum string voltage spec.
FWIW in 3 years with a couple (now three) Powerwalls the longest outage I've had is 48 minutes. So there are many situations where, if the user is not doing power arbitrage, a single Powerwall can provide a decent amount of backup utility. Steady state load is quite low for many. Most people don't have an idea because they're not looking at the data. They might see total energy consumed but translating that into useful units is not intuitive for most. If they divided the kWh used per month 730 (approximate number of hours in a month) they would have a better sense of average hourly consumption.
I just looked up the average electric usage in the US it looks like just smidge over 30 kWh/day. For California it is less than 20 kWh/day. So one Powerwall (with a little conservation) can get a lot of people past a night time outage. The other potentially useful thing for higher power capacity are for people with pumps. The single powerwall would likely handle more of those situations (the need for startup surge).
If I had to place a bet on what they're doing this is the horse I would put my money on.
Assuming no other power sources into the main service panel they have a very "simple" system to control. They know how much power is flowing into or from the main service panel since they can monitor the only two sources, the grid and their "generation/solar/whatever your call it" panel. With coordinated control of the inverter or inverters (they can optimize the second inverter later if they want) they can limit the output of the Tesla inverters to guaranteed that they don't exceed the bus ratings per whatever rule they must comply with. Technology wise this sounds relative straight forward. Installation wise this is game changing. I'm assuming they have done their regulatory homework.
I think this is brilliant. Similar in the brilliance of the AC coupled Powerwall 2. The total addressable market of this configuration is so much bigger than the current product. And as @wwhitney already said, they can still use the Gateway2 for complicated configurations.
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