Elon tweets: Solar Roof and solar panels will only be sold integrated with Powerwall

[DJVoorhees]

Looking at the tesla website or PW, it says Available for purchase with solar. I see nothing on the solar side that says you have to buy a PW, at the moment.

Elon tweeted it - there is no grey area.

Tesla is only bundling solar products and Powerwall together going forward

Elon Musk announced that Tesla is going to bundle its solar products, solar roofs and solar panels, with its Powerwall...

electrek.co

Elon Musk announced that Tesla is going to bundle its solar products, solar roofs and solar panels, with its Powerwall home battery pack going forward.
You are not going to be able to buy one without the other starting next week.

 

[holeydonut]

Thanks for listening in on the earnings call. You have added a lot of great data points here.

I can see where he might be coming from, trying to simplify installations. However, electrons move from high potential to low, so it doesn't matter if the plan is meter - Powerwall- load /solar or meter - load / solar - Powerwall, except from the rewiring main panels. It seems like many people here have had real issues around main service panels. If the new system can take 225 Amp feed throughs in their internal busbars, it would simplify those installations where the meter isn't integrated into the main panel. You could make a Tesla "combiner box" be the high current center of a system.

Much as it is fun to speculate, the devil is in the details about what problems the proposed changes might fix, and what they might induce. Tesla certainly now has the benefit of living through a large number of installs, so that data is probably being put to good use, or at least I hope that it is being put to good use.

We shall see...

All the best,

BG

Yeah, using my own house as a sample size of one (one gigantic painful learning experience)... here are the blockers that I encountered that the County, PG&E, Sunrun, or somebody off the street could throw up as a reason Elon's idea wouldn't be allowed. My house was built in the early 90s. I can't imagine how crazy some homes get over the last century.

1) My main panel was a main lug only (MLO) style with no utility service disconnect breaker. As a result, this panel would not allow a line-side tap on a solar installation. Presumably adding an extra 60A coming from batteries would further make an line-side tap a gigantic no-no.

2) My gas riser is within 36" of my main service panel. So anything going into this man service panel that isn't just a new OCPD is against the Greenbook rules. Even if I had a "normal" MSP instead of a MLO one, PG&E would have to disconnect my service to allow that line-side tap to be installed between the meter socket and service disconnect. And PG&E would say "hell no" to the line-side tap.

3) Also related to the 36" distance to the riser, a line-side tap needs a disconnecting means that is independent of the service disconnect breaker in the main panel. Presumably, the only way to get a new disconnect to reach the line-side-tap would need some conduit near the main service panel. And of course, this is not allowed per Greenbook rules due to the whole exploding gas riser risk.

4) When my budget would only allow for 2 batteries, I was stuck with a partial home backup solution. Even if I had a normal main service panel that was like 10 feet away from the gas riser; I still needed some clever design to get the partial home backup solution to work. Since PG&E thought 2 batteries + 8 kWp of solar would explode my 200A busbar, I can only imagine what BS that 120 percent rule would throw into Elon's cool plan.

 

[wwhitney]

1) My main panel was a main lug only (MLO) style with no utility service disconnect breaker. As a result, this panel would not allow a line-side tap on a solar installation. Presumably adding an extra 60A coming from batteries would further make an line-side tap a gigantic no-no.

FWIW, such a panel should be fine for a line side tap and when it is existing would be the easiest/simplest way to do one. Not sure what authority was telling you it wouldn't be allowed, but that would be a minority interpretation that could hopefully be overturned.

However, in new installations an MLO service panel is prohibited under the 2020 NEC, which will be in force in CA in 2023, I believe. Not sure how the idea of adding another breaker to an existing MLO service panel will be handled at that point.

Cheers, Wayne

 

[holeydonut]

FWIW, such a panel should be fine for a line side tap and when it is existing would be the easiest/simplest way to do one. Not sure what authority was telling you it wouldn't be allowed, but that would be a minority interpretation that could hopefully be overturned.

However, in new installations an MLO service panel is prohibited under the 2020 NEC, which will be in force in CA in 2023, I believe. Not sure how the idea of adding another breaker to an existing MLO service panel will be handled at that point.

Cheers, Wayne

My apologies in advance for linking to another forum, but the explanation I was given was similar to what this "GoldDigger" user said here:

Main Panel supply side connection & 120 % rule questions.

The main panel is rated 200amps w/ no main breaker, has bus bar w/qty.6 locations for breakers. Currently contains qty.2- 100amp breakers feeding sub-panels. Qestion 1, If qty.2 seperate 40amp pv breakers are added to this bus bar, this would be considered a supply-side connection and not...

forums.mikeholt.com

The 120% rule is applied to the bus in a panel and to the wires in a feeder or a line side wire (not calling it a tap at this point, since we are not limiting where it goes.) Since there is no single main breaker, you do not have any current limit in power supplied to the bus except whatever OCPD is present on the POCO side. So you now have a potentially unlimited supply of current to the bus from POCO, but at least the size of the service. And you have the already installed 200A of load in the breakers feeding the subpanels. You are not required to provide overcurrent protection to the service, but you are required to protect the bus. The problem is that with more spaces available in the panel, more load could be added and the current from the service plus the current from the PV together would then exceed the bus rating.

Since you are connecting to the bus rather than to the service wires, this is NOT a line side tap for the purpose of the 120% rule, and since there is no main, I am not sure how you would be able to apply the 120% rule correctly. And if you could, the total of 80A of the PV would exceed the 120% limit.
Bottom line: I do not see any way that you can legally do this and the PV would have to come into a second panel connected to the service directly (a true line side tap) or a main breaker would have to be installed in the panel so that the 120% calculation could be done.

Basically my understanding that in the absence of a single service disconnect breaker... the 120 percent rule gets difficult to apply. And since PG&E considered 2x Powerwalls (40A) + 6.8 kWp AC solar (35A) as total export/generation then I would blow up the 120 percent rule even if you tried to apply it on a line-side tap. And no, this weird Challenger box didn't seem to have the ability for someone to add a main breaker to it.

I noticed I had some neighbors with solar feeding their old Challenger boxes, but the newer installed systems all had new MSPs. I asked one of the homeowners with a new MSP (but no ESS), and he said his installer got his plans shut down with adding solar to his main panel in 2018. So he had to pay a few grand extra for the replacement main panel that was "solar ready". Of course he didn't get the BS headaches that PG&E hit him with around the like-for-like issue and his gas riser. I got the special treatment on that one.

Edit, and I think NEC 690.64 says the line-side tap needs to go between the service entry and a "service disconnect overcurrent device". Since the MLO doesn't have a service disconnect ... I have no idea what all this means haha.

 

[wwhitney]

My apologies in advance for linking to another forum, but the explanation I was given was similar to what this "GoldDigger" user said here:

Sure, but if you read that whole thread, Golddigger's initial comment was wrong

Basically my understanding that in the absence of a single service disconnect breaker... the 120 percent rule gets difficult to apply.

The 120% rule doesn't apply to line side interconnections, so that's moot.

this weird Challenger box

If I recall, old Challenger panels have some issues, so replacing it was probably a good move, whether it was required or not.

Cheers, Wayne

 

[holeydonut]

Sure, but if you read that whole thread, Golddigger's initial comment was wrong


The 120% rule doesn't apply to line side interconnections, so that's moot.


If I recall, old Challenger panels have some issues, so replacing it was probably a good move, whether it was required or not.

Cheers, Wayne

Yeah, I didn't mean to assert my understanding was right - it was just what was explained to me haha. If PG&E is the one that thinks your design doesn't comply; who is going to convince them otherwise? If Sunrun with their army of peoples wasn't ready to try... why would Tesla any other local installer (ones with out @Vines) try?

I know Sunrun tried to tell PG&E that the breakers for the stand-alone generation panel (with 2x Powerwalls and solar) would be on one end of the MLO busbar with the PoCo entry on the other side. So, they tried to say that I could still keep my 200A of home load breakers in the middle and the busbar and there wouldn't be risk. But PG&E said no. Maybe it was the batteries? I really can't tell.

To make things worse, then Sunrun said, fine we'll just put a new main service panel (one with a service disconnecting OCPD). PG&E still countered saying even with a brand new 225A busbar + 200A rated main service panel... the only way they'd allow this new design with a partial home backup would be if I de-rated all home loads down to 125A (I'd need a 125A service disconnect OCPD in my main panel). This would effectively kill my ability to add an EV later.

PG&E's logic still confuses me on this. But I think it's because they really thought my home could consume 125A from the utility while my batteries and solar exported 75A back to the grid. I'm still confused how this event could ever happen.

So PG&E pinned Sunrun into one and only one design. I had to do a whole home backup in a way that kind of mimics what Elon said as his perfect scenario (of course, I needed a ton of new equipment).

Meter Socket >> Disconnecting Means >> TEG2
Then Generation Panel and Backup Loads behind the Gateway.

PG&E was fine with this as long as they put that weird statement about how my system would confirm with their NEM requirements.

 

[wwhitney]

Sounds like you got stuck with a poorly informed reviewer at PG&E, and Sunrun let you down by not knowing how to escalate things to get a competent PG&E review.

Cheers, Wayne

 

[Zinc_Saucier]

My home has the utility meter on the left side of the box and the main panel on the right side. The underground service line feeds up to the meter socket, then wires from the load side of the meter socket feed straight through the center divider of the box to the main breaker. The main breaker and all of the home circuit breakers are on the same bus bars. How can the powerwall be interposed between the meter and the main panel in this case? Are most homes wired differently with a separate meter box?

I’ve never had a house with a combo meter/panel before. All the places I’ve lived have the meter on the side of the house and a panel in the basement/garage. Not sure if it’s a regional thing, but that’s my experience in the North East

 

[willow_hiller]

For those familiar with the electric code, I'm also curious how grid isolation will work with this side-tap install configuration. When I read "side-tap" I imagine a junction between the Powerwall outputs and the grid lines, but I'm guessing there must be some sort of transfer switch installed at that junction to prevent backfeeding when the grid goes down?

 

[wwhitney]

It's not "side tap", it's "line side" tap vs "load side" tap. For the case of PV and/or non-backup ESS, it refers to whether the path from the inverters to the grid passes through the existing service disconnect. If it does, the interconnection is on the load side of the service disconnect; if it doesn't it's on the line side of the service disconnect.

For partial house backup, you could do a line side tap, move all the loads to be backed up to a new panel behind the Gateway, and leave the non-back up loads in the existing panel. Then you end up with two service disconnects, one for the backed up side and one for the non-backed up side.

For whole house backup, this is not a logical distinction that makes sense, as the order always has to be meter -- service disconnect (possibly inside the Gateway) -- Gateway. It could be an implementation distinction in how you get there: intercept the service conductors between the meter and the existing service disconnect, vs intercepting the feeder after the service disconnect. That would affect the grounding and bonding details. Not sure if the terminology is used this way in this context.

Cheers, Wayne

 

[Carl_Drogo]

Elon mentioned in some tweets and on the earnings call that they are simplifying the configurations for installing solar. I'm thinking about getting a solar roof, but I don't know much about electricity and trying to understand the implications. Will this eliminate net metering or have any other real world implications? Are any other features people currently enjoy, for example, going away?

Thanks

 

[aubreymcfato]

Elon mentioned in some tweets and on the earnings call that they are simplifying the configurations for installing solar. I'm thinking about getting a solar roof, but I don't know much about electricity and trying to understand the implications. Will this eliminate net metering or have any other real world implications? Are any other features people currently enjoy, for example, going away?

Thanks

They will put a powerwall or two in the bundle. For the foreseeable feature it's solar + storage together.

 

[Ampster]

It just eliminates redundant inverters. That should bring the total cost down of a combined system. It should not affect net metering because they would sill need a gateway or transfer switch to comply with code.
I also don't know where they are with compliance with the new UL 2020 requirements but it may be easier to get the entire system certified by UL, rather than the component parts. From a marketing standpoint it allows them to pick the low hanging fruit and let others deal with the issues of integration with existing solar.

 

[pdx_m3s]

So Elon cleared up the Solar+PW being the only configuration, however, there's still some details we don't know yet.

Will the PV be DC-coupled, eliminating the need for a PV inverter?
Will this eliminate the need for the Gateway?

 

[skepticcyclist]

So Elon cleared up the Solar+PW being the only configuration, however, there's still some details we don't know yet.

Will the PV be DC-coupled, eliminating the need for a PV inverter?
Will this eliminate the need for the Gateway?

And if there is no gateway, then what will be used for the network and as a transfer switch?

 

[Ampster]

Will the PV be DC-coupled, eliminating the need for a PV inverter?
Will this eliminate the need for the Gateway

It will eliminate one inverter but the gateway or transfer switch will still be needed for code to island from the grid when grid is down.
In one sense it goes back to the efficiency of the Powerwall 1 which was DC coupled.
The networking would be integrated with a single inverter.

 

[MP3Mike]

Will the PV be DC-coupled, eliminating the need for a PV inverter?
Will this eliminate the need for the Gateway?

You have to have a Gateway if you have Powerwalls. So it won't be eliminated.

But we have seen rumor that there will be a new Gateway/Inverter combination device. If true, that would likely mean the inverter is removed from the Powerwalls and the Solar/Powerwalls are DC coupled.

 

[h2ofun]

You have to have a Gateway if you have Powerwalls. So it won't be eliminated.

But we have seen rumor that there will be a new Gateway/Inverter combination device. If true, that would likely mean the inverter is removed from the Powerwalls and the Solar/Powerwalls are DC coupled.

They sold I believe a powerwall that was DC in the past without the inverter in them like today

 

[Ampster]

They sold I believe a powerwall that was DC in the past without the inverter in them like today

Yes that was the original Powerwall 1. It was more efficient but used third party inverters. I think it was also before the merger with Solar City.

 

[MP3Mike]

They sold I believe a powerwall that was DC in the past without the inverter in them like today

Correct Powerwall 1 was a DC based system. Powerwall 2 was supposed to come as either AC or DC, but they cancelled the DC variant before it ever made it to market. (Maybe it wasn't cancelled, it was just delayed until now?)

edit: corrected that PW1 was never available as an AC unit.