Yes, another way of saying how AC coupling works. You are also correct that the Powerwall does this and it is a promised feature of the Skybox. I am betting on that happening fairly soon.
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Powerwall 2 supply issues
- Thread starter Myke Hines
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- powerwall install
Yes the features were integrated and simpler wiring and a broader voltage range of solar voltage. It does have only one MPPT input but the wide range will allow me to incrementally add solar as I try to optimize my systems.
ceekz
Member
We have an existing Solar City system, but it was designed to generate about half the power needed for the household. Now that we have a Model 3, we want to add more panels and two PWs to charge the car, as well as allow the use of solar energy if the grid is down. Reserved the PWs in early October with the understanding that Tesla was 6-8 months out for production, but received a call this morning to start the installation process. The rep didn't know that we were adding panels, so that will delay things a bit, but it is was good to get a call in November instead of next year as anticipated.
I would be interested to hear if someone else added panels to an existing system to support new PWs. Will it require an additional system, or a replacement, or just added panels? I've heard differing opinions.
I would be interested to hear if someone else added panels to an existing system to support new PWs. Will it require an additional system, or a replacement, or just added panels? I've heard differing opinions.
How to expand a solar system depends on what you already have, whether you own the system or have a PPA, etc. Most likely they will just add an inverter appropriate for the new panels and leave the existing stuff alone, electrically at least. They may change the racking a little to expand the panel area if adjacent space is available.
ceekz
Member
That is my hope! I believe things get complicated fast when changing an existing system because of how much the regulations and agreement terms with the local utilities are changing.
vv
I don't know what NEM version you are on but if you are on NEM 1.0 there is a limit to how much grid tied panels you can add without triggering conversion to NEM 2.0, which has additional costs. Since you are adding two Powerwalls you may want to ask them if there are options to add panels that are not grid tied but charge the Powerwalls. That may take a hybrid inverter and be too out of the box for their cookie cutter grid tie approach.
ceekz
Member
I don't know the answer to that, but the Tesla power folks said that I have to add at least 8 panels (but no more than required to provide 100% of the power used by the household) to even qualify for a second system. I'll be sure to check into this when I have a site visit scheduled, thank you!
So I am in south Florida, I spoke with a Tesla Energy salesperson who is local here. He said that I can get a Powerwall if I buy their solar panels. Tesla employees would install both of them. If I don't buy the solar panels, then I can't get the Powerwall from the local Tesla people, and I have to contact the Nevada office, which will tell me that Powerwalls are not available in my area.
I started getting solar panel & PW2 on February 8th 2018 and couple weeks later, was told the PW2's are on back order and asked if I want to split the solar install from the PW2 or install them at the same time. I went with split and my Energy Consultant said the PW2 should be installed August/September. Said great. After a delay with my city building inspection issuing the permit, finally got the panels installed on August 16th. The lead installer said they got a shipment of 29 PW2 but doesn't know if mine was in there (it wasn't, as I am still waiting). Like others, emails, calls in to Tesla get lost in the void. At this time, I don't know who my EC or Sales Rep is any more.
Has anyone considered a Pika Energy Inverter? I've been looking at them for a few months and I've been following the company for a while. I've gone ahead and asked for an installer to discuss a system. Not cheap really but outside of the powerwall this seems to have a nice simple setup and a decent battery (also Panasonic).
Theoretically, the Pika system is very good. It uses a HVDC bus system and DC-DC converters to push and pull current on the bus. However, the system is totally closed. I talked to them about whether it would be possible to work with them to interface other elements into their system, even under NDA. They were not interested. Also, I believe the batteries they use are Panasonic prismatic cells and they are VERY expensive on a per kWh basis.
Ulmo
Active Member
I get the distinct impression they have pretty exact customer assignment of the exact number of PowerWalls produced, and never assign more or less customers for PowerWalls than they have in the production pipeline. That has been the experience of everyone I've read about: once Tesla says you will get them and moves ahead with your agreement, you will get them. That's what happened for mine. The install date is firm. So, this is how I think they do it: their production pipeline gives them expected production output numbers. Sales force matches expected output numbers to contract signing team assignments, and uses the average contract signing lead time to have the right time buffer; this slightly desynchronizes Just In Time, but wait ... there's more! After the contract signing, the sales team then sends it to scheduling. Scheduling assigns the install date to firm PowerWall production numbers, AGAIN. They probably target conservatively, overproduce, and then use the overproduction for further scheduling assignments. That's my take on the PowerWall production system and how they never run out when they say you'll get one once they move forward with contract signing, while simultaneously leave so many people in the lurch saying "there's none available".
mspohr
Well-Known Member
I also wonder about the availability of installers. They seem to have two systems, their own employee installers and independent installers. They probably have more control of their own installers so scheduling is more exact. Independents can be more difficult.
They told me that I'm in an area where they use independent installers so I'm worried that there will be delays while they try to round up some guy. I ordered a few months ago, didn't hear anything from them and finally called. They told me to check back Jan or Feb. Didn't sound too definite. I live about 50 miles from the Gigafactory so transport would not be a problem. I could even go and pick it up myself... or the installer could. Problem is more in production and sorting out the installer.
Ulmo
Active Member
Ulmo
Active Member
That could definitely be a thing too. Not to be mean or anything by disagreeing, but my guess (stress guess here) based upon what I've seen so far (things could change) is that the independent installers are given the same stocking management that the in-house installers get: once Tesla Energy has designated a PowerWall for you, you get it, regardless of paperwork, staffing, and other logistics shenanigans.
I think this is a "medium hard" reservation (still guessing based upon what I've seen): using a not so rare example of contractors applied to the more rare example of Tesla: if somehow everyone trips up and just flubs your install paperwork and date, and the installer suddenly gets some hormones and puts you on schedule to get out of the house to get some meditation time away from their spouse and they have no other excuse but contract with you, they show up at your house and realize "oh damnit, I forgot to bring a battery", calls Tesla up, asks for the stock pickup address, and finds out "none are in stock", then protests, saying "I know the agreement was signed and I'm supposed to install!" and Tesla tells them "well you took forever, but we'll have one for you in x days (where x is around 5)", so the installer pulls up to your driveway, sits in his van making calls, then drives off, all the while you're looking out your window at him thinking "come in already", then you receive a call from him saying "Something came up ... an emergency, yeah that's it ... but can I reschedule for tomorrow? Let's see here ... actually, tomorrow at 9AM is filled ... how about next week?" and comes back in 6 days with the PowerWall in tow. Of course, that kind of installer would probably spend more time in his living room (van) than in your install, just so he can get some meditation time ... it's been known to happen. My point is that even in the worst of scheduling and paperwork foul ups, that once Tesla has deemed you "agreement worthy" and especially once they have signed the agreement and sent it off to installation assignment, they are ready to deliver, hopefully in orderly fashion and so far that's most of all we've seen, but I think even in the less clean situations, too.
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P.S., as I sit here thinking about this more after a good sleep, I realize that battery cells in the GigaFactory are conditioned and tested in big racks. After a few conditioning and testing cycles, Tesla pretty much knows the failure rate of that batch even though they'll need to finish conditioning and testing them for full production quality. Tesla also knows the production rate of pack assembly (PowerWall boxes, etc.). They can do the Materials build tree scheduling right then and there, and sales force agreements and installation scheduling can come out of that tree. While the sales force is interacting with Engineering and you, the battery cells can still be in the Panasonic-run GigaFactory (with Tesla having data on what is in the pipeline), each battery cell can be (soft-)assigned even while it is in conditioning and testing, and then the manufacturing system puts a guess when each battery cell and PowerWall materials will be built into a PowerWall, that estimated build time, plus a few buffer days, plus logistics time to move the PowerWall into the right stock warehouse, are calculated, and it is made available for an install date, which had already been aligned by the sales force agreement scheduling.
They could also wing it and just look at the production output and align according to guesses as long as they have enough inventory buffer. That probably works just as well. They could paint extras red and have them signed and sent up for Referral Rewards installs.
Who knows what they really do. But in terms of us understanding the system, my point is you can call Tesla all day long and ask "Do you have PowerWalls in stock?" and the answer means absolutely nothing: it's all Just In Time manufacturing and logistics, so "stock" is a temporary state that means nothing. "In Stock" means you don't get it: someone else does (because the only reason it was stocked in the first place is that it was already designated and built for them, plus or minus). "Not In Stock" is the usual state when you DO get it, because yours is still being made when they assign it to you. In such a system, "stock" is a logistics term, not an ordering term.
P.P.S., since they can use third party battery manufacturers, the estimate points may be slightly different than what I said, but a battery being shipped on a ship across the Pacific Ocean probably takes a long time just like a battery in a factory rack being conditioned and tested, and I bet they have some idea of how many batteries are in transit to them on ships (since they ordered them in the first place). Shortfalls (because containers had a short fall into the ocean and got lost) are probably made up by fulfilling commercial customer projects a little less fast (PowerPacks, etc.), which usually have a bit of wiggle room. That's why it's good (necessary for the survival of the business) to have a wide variety of products and customers in every large business and in most businesses of any size: flexibility in sales and installation (delivery).
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If anybody gets any insights into how all this works, that's fine. But the whole idea of "stock" seems naive in this type of seller's market.
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By my theory, the choke point is derived from the manufacturing, but is implemented via the sales force agreement scheduling (hidden from us), and they know that once we know that, we'll just nag them until they "designate" an agreement for us, so they've probably already practiced the many ways of saying "no" to us for years at this point, even though it is entirely up to them. Remember: if they don't say "no" to you, they have to say "no" to someone else they were about to say "yes" to, so although most things in life are not zero-sum, in a seller's market aspects of this market are zero-sum. If looking at this particular situation, a useful question to Tesla is "What is the general projection for general time period for when you'll want to do an agreement for our PowerWall project?", and they'll have to get back to you since they'd have to ask the scheduling boss. It's probably hard to make such projections given variability of resources, such as Model 3 production taking capacity, sales force, engineers, and permit filing worker availability, and installer availability and scheduling, and since it takes labor to do such scheduling estimates (which would likely be wrong anyway and set up some people for being mad at getting wrong estimates), one way they save money is not doing the scheduling twice, and just tell you when they tell you. But if you want a rough idea, then asking for a rough estimate might (I stress might) give you some idea. It looks like they're already letting out some rough ideas just through our group knowledge.
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It sounds like you thought that I meant that their battery pack was expensive because the prismatic cells themselves are expensive. No, I just meant that their lithium ion solution uses prismatic cells and adding their battery pack to their solar inverter is very expensive when you compare it on a per kWh basis.
The Powerwall and Solar system was done by installers wearing Tesla shirts and hoodies, driving vehicles marked as “Solarcity DBA Tesla”They knocked out 90% of the install in one day and finished early on the next.
