GateFather
Member
Ahhh so now I am wondering if I should wait a bit - or move forward with this design expecting install won't happen until Q3 and perhaps they will be ready by then and my design will change?
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Tesla Says I Can Only Get *ONE* Powerwall bc of my Utility's Rules
- Thread starter Jeremy3292
- Start date
GateFather
Member
Also - as a side note - it looks like they intend to put all 58 of may panels on just 2 strings, one for the panels on the front of the home and one for the back:
This seems like very inefficient design to account for shade that may hit different parts of the house from trees around my backyard throughout the day. Why would they do this instead of splitting each roofline into 4 quadrants since the Powerwall+ have 4 MPPTs available? I mentioned this to my advisor.
This seems like very inefficient design to account for shade that may hit different parts of the house from trees around my backyard throughout the day. Why would they do this instead of splitting each roofline into 4 quadrants since the Powerwall+ have 4 MPPTs available? I mentioned this to my advisor.
Your utility limits you to 21kW of Inverters, so one PW3. If that is enough for you waiting is an option, though maybe they will combine a single PW3 with stand-alone inverters for larger solar installs. But that limits you to 11.5kW of backup power, probably less than you are looking for.
It almost seems like they should downgraded the PW3 inverters to ~10kW, so that you can get two of them installed even in areas with the restrictive utility rules.
I don't think that shows the string design. (I think MP#, stands for Mounting Plane #.) Even as such that design has three inverters, so at a minimum that is three strings.
I edited my prior post with the tweet - check back to that post.
As far as stringing goes, they will update the stringing for you if you provide a legit reason. I had some shading from trees and sent them pics and they updated it no problem.
I honestly would not wait for the PW3. My conclusion was same as yours: if you are only getting 1 PW then the power output increase is certainly important. With 3+ PW’s you don’t need the extra power output bc you have so many PW’s already. So the only thing PW3 gives you is LFP chemistry which is decided who cares since the PW2/+ have a 10 year warranty anyways.
If you change your design and ask for PW3 later in Q3, you start the process all over again. Design, approval, and then permitting. Your permit must match the plans so if you change to PW3, a new permit is required.
This part of your plan shows 6 strings. (S1A/B, S2A/B, S3A/B, S4A/B, S5A/B, and S6)He meant Powerwall Plus and Powerwall 2s as my planset shows this design:
GateFather
Member
I think if/when PW3 expansion only model comes out, they would likely be able to supplement it with their stand-alone inverters like they have spec'd for my system now. It would be the 2 PW+ 7.6kw inverters and a separate 5.7kw inverter. I would still be limited to the 11.5kw + one of their 7.6kw which would be only 19.1 and therefore require likely less panels. Also not ideal, but not all the way down to 11.5kw.
Ah thank you - this makes much more sense. Doesn't look like they shared the string config with me in the plan set then. Will need to request that.
Where did you find this? Can you share the link? Would like to read through it for curiosity
The source video is no longer available, but the information is in this thread: Powerwall 3 Roadmap - 3 Phase Coming!
At night, or when solar is not available you would be limited to 11.5kW. If that is enough to support all of your backup needs than a single PW3 would be an option. (You could even get it installed now, and then add 3 DC expansion batteries later, assuming you trust that Tesla will actually follow through and make them available.)
GateFather
Member
Ah I see. 11.5kW is definitely not enough for my home. Not that this would be a common occurrence, but I have 2 model Ys, for example and just charging them from PW would take up 20kw (maxing both at 40amps). Unfortunately, this would also be the max of the 2PW+ and 2PW 2 systems they are planning to install as of now if I agree. Again, in an outage, I doubt I would actually want to be charging my cars this way and when not in an outage, the grid can supplement the PWs if needed (say for powering the home overnight if I want to go that route instead of keeping PW at 100% to send excess solar to the grid during the day). Based on the timelines I've seen though, I feel like I could agree to the 2PW+ and 2PW2 today, and very possibly get something else in however many months from now until the system would actually be installed. I've been waiting a week just for them to get me their license and certificate of liability insurance for the HOA lol.
GateFather
Member
Oh missed this! I wonder if there is anywhere showing how they plan to breakup the strings.
I did see this..
You’ll have to ask for exactly which panels are tied to which strings. If you’re shading isn’t bad it probably doesn’t matter. My roof was a simple plane so moving the strings made sense with the shade. Probably doesn’t matter for total output though, minimal at best.
GateFather
Member
My backyard is surrounded by trees - this drone video was shot around 6pm if I'm not mistaken -
bsf29
Member
@Jeremy3292 Duke Energy has really screwed their customers with their new rate plan. It's really hard to understand how they got this rate case approved when solar customers are overpaying. I agree that net metering really isn't fair to the utility because there is much more cost involved than the electric rate they charge, but there is no justification with a monthly charge for a bi-directional meter that is a 1 time programming change to the existing meters they are installing. They also added a higher connection fee if you are a solar customer. Utility provider cost/overhead does get more complicated when homes can put excess solar on the grid and they have to balance their system. My co-op allows up to 25KWh systems before the owner has to fall into another plan but this is solar and not solar + battery. No idea why your installer is including the battery when you are only exporting excess solar and not drain your battery. 2 people I know in Duke's territory are luckily grandfathered in to the old net meter plan, but they are very concerned about their rate when it expires in 2027. Even Duke's TOU plans seem to be designed to penalize customers and I told my daughter not to sign up. If I were a new Duke Energy solar customer, there is no way I would export anything to the grid and just stick with their normal rate plan. My Generac PWRCell system allows for this configuration and how I ran for the week it took to get my installation inspected/meter upgrade/approval by my co-op. I'm assuming Tesla PowerWall has something similar. When I was designing/purchasing my system I wasn't too concerned with the payback, I was looking at keeping my electric cost down and whole home backup since we work from home and have 2 Tesla to charge. As my installer pointed out, adding battery to a solar system makes it more difficult to have a payback because the batteries will need replaced at least once during your panel life.
Tbh it really doesn’t matter at the end of the day for yearly output. You’ll waste time trying to figure it out and get Tesla to do it how you want it. You also are going to have a ton of panels it looks like so I would just accept the stringing and move on.
I’m in SC not NC, so I don’t know anything about Duke in NC. I try to give utilities the benefit of the doubt bc generally speaking solar customers want all the benefits and none of the expenses. The utility still has to service your address and fix the power lines after weather events, etc. Most states don’t even allow you disconnect power from your address and tell the utility to come get their meter.
In 2021 to reach an agreement on solar net metering, Duke agreed to a TOU rate schedule structure that can’t change for 10 years (2031). We have a $30 min bill charge here with TOU rates and monthly netting in the TOU periods. 6-9pm is peak rates with an additional peak period of 6-9am for Dec, Jan, and Feb. I think it is pretty fair for now, but you definitely need batteries to avoid the peak times. My solar install is pending with 3 Powerwalls, which is over 40 kWh of storage. I researched the Duke solar rate schedule and did lots of research before ordering. My goal was to offset as much energy usage with solar as I can and be somewhat independent, which I think I will achieve other than in the winter. The winter is impossible to be off grid bc of the low sun and heat pump usage. So I feel pretty good about it.
We also have a 25% state solar tax credit here in SC, which really makes it easy to go solar. With the 30% federal credit I will only pay $22,500 of the $50,000 total cost. If I lived in another state without that state tax credit the 3 PW’s would certainly be hard to afford and a tough sell. So I can see how solar doesn’t really make sense these days by itself without battery storage bc you need to avoid the peak periods to make it worth it.
GregBallantyne
Member
Another wrinkle here..... I commented on the design regarding stringing, with earlier and later daily shading observation as my basis. The installation crew (regional certified Tesla installer, not Tesla) was run by a fellow with significant solar experience, and adjusted the design during installation. I've been happy with performance, and believe that he probably did better at that part of it than I would have. Since I was getting Solar Roof installed rather than panels, there were other non active tile decisions also made during installation. BTW, my design comments increased output and also resulted in a stuffed roof that had little to no inactive tiles outside those requiring cutting/trim.
Bottom line, a number of decisions are likely to be made at the installation stage that are actually design level decisions.
GateFather
Member
Thanks this is good to know, if not a little worrisome since I'd much rather have a fully thought out, designed, and agreed on design before installation date since I don't necessarily know who will be installing and how knowledgeable they'll be. Also won't know if installers will have knowledge of which parts of my roof are shaded throughout the day. Maybe I will spend one sunny day flying my drone up hourly and taking a snapshot of both sides of the roof to put together on a one-pager for them for installation day. I think this could help them see how/where he trees shade from hour to hour over the course of a day. Probably would be smart for me to do this now, and again in June/July (assuming they aren't installed by then) since the sun moves differently in the summer than now.
GregBallantyne
Member
My design docs included a roof layout that identified which tiles were MP1, MP2, etc.... While my installation was done by a Tesla Certified Installer, the design was from Tesla
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