Solar Roof

Advise Needed - Wait Or Change System Design

I placed my solar roof back in March and current status is "Installation Coming Soon".
However this had been going on for months and I don't think I will be able to get the tax credit this year.

A lot had changed since March and my electric bill had gone up a lot.
Back then my bill is around $150 and now it's around $200+.
Now both me and my wife is working from home and I got my model y and that's the reason the bill raise to $200+.
Based on this tesla ordering page is recommending a 8.2kW instead of 6.2kW of what I have.

Do you think I should stick with this considering all the back log for permit and installation or just ask Tesla to change my design to 8.2kW?
One of Tesla representative told me as of now there is no way to increase the system size after installation.

Thank you in advance for your opinion.


  • Make any changes NOW! You'll forever regret a too-small solar PV installation.

    You'll probably get stuck with a 2021 installation, if you make any new changes, though. Recognize that the tax credit's applicable tax year is determined by when *construction* starts. So it will probably cost you 4% of the installation price, if it happens in 2021. The tax credit in 2020 is 26%. In 2021 it's 22%. The solar tax credit goes away entirely in 2022, unless it's extended again.
  • Have you scheduled your install date yet? Did you check with your city Building Permit Department to see if permit was submitted/approved? If none of the above, I do not know if it would make any difference if you change your configuration now, Tesla seems to like to hide what they are doing as far as your project goes, company line I believe. I hate the fact that everyone asks you about your monthly electricity cost for system estimate, energy cost is only good for marketing purpose to show breakeven time. What kind of rate plan you are on? I am on tier rate so as soon as I go over the baseline rate will jump, and jump even more if I go over the 2nd tier. Yes I am using more electricity but I get charged a lot more for going over tier limit. You should really look at kWh you use recently and see if your planned system will meet it, if not you need to tell you project advisor that you need to up your system, even if it means a delay in the install. While you are at it, add 10% to the new estimate so you don’t have to worry about using more. I say 10% because some utility companies would not let you exceed that, but I think Tesla will play the number game to get you the size you want within reason. It also depends where you are, Tesla’s energy output estimate is usually conservative. My project advisor told me I would get 5 to 15% more than what is on paper, but I would not count on that and size more than my energy consumption, and don’t forget about PW.
  • I asked my advisor same exact thing yesterday. My install date is in Dec, and he said it would set back everything done so far, as if we are starting the whole process again. I would've considered it since I've already waited a long time, but it turns out there's no way to get more out of my system due to my roof pitch and penetrations, etc... with that being said, I am fully convinced that you will be able to swap out solar tiles with better more efficient tiles getting you more juice in the future (scientifically doesn't make sense not to be able to). Also, we will all be going back to work eventually and won't be using as much as electricity as we have been these last 6 months.
  • I have appointment schedule for Nov 20th for assessment.
    Maybe I will talk to the advisor by then.

    I'm currently on Tier 2 so the solar roof should get it down to Tier 1?
    My concern is if I change the design I might not even get it install by 2021 and don't get any tax incentive.
  • For the month that your electricity cost was $200.00, how many kWh did you use? It should tell you how many kWh in baseline, how many kWh in Tier 1 or Tier 2 if you exceeded even Tier 1. You did not say what utility company services your area, I'm in Northern CA with PG&E and they require new solar customer to switch to TOU though I find EV-A rate is much cheaper for me. What is the annual energy production with your 6.2 kW as quoted by Tesla, it should be on your Customer Layout. I assume it would be around 6900 kWh, how close would it meet your energy consumption?

    The assessment is for pre-installation? If that is the case then you may not want to change anything as it definitely will push you out to next year. As long as your system can provide up to 80% of your consumption your monthly electricity should not be too bad.
  • 791kWh, Tier 1 usage = 329.6 & Tier 2 usage = 461.5.
    I'm with PG&E East Bay but they currently have this weird "East Bay Community Energy Electric Generation Charges" going on so the bill is a bit confusing.

    Tesla solar roof customer layout said it would generate an estimate of 7621kWh annual production. I don't think we would use so much energy in spring and fall so I think it still cover up to 80% of my energy usage.

    At this point i'm thinking to keep the design.
  • Tesla must be placing most of your solar cells on a South facing roof without shades. My 6.5 kW with a generic estimate of 10014 kWh output is only quoted as getting 7250 kWh, though my last Project Advisor told me that California customers generally get 5 to 15% more than the quoted output. Most Bay Area counties are required a default of 50% renewable and opt-in 100%, PG&E does 100% solar choice now but it was not available when I opt-in 100% with Peninsula Clean Energy. So energy generation is charged by Peninsula Clean Energy but PG&E adds their delivery charge on top of that. But kWh is kWh and it syncs with your PG&E rate plan. Your East Bay Community Energy Electric is like my Peninsular Clean Energy, they source their power from wind and solar and sends them to PG&E on demand. I think you will be fine but it would help if you have Powerwalls in your system, it helps avoiding peak rate and extends your self-powered period at night not to mention keeping your lights on during PSPS and the rare Winter storms. If you do not have it on your order already you can wait till after they install your roof, you would lose the discount but at least it would not delay your project. If you add the Powerwalls now they would have to resubmit your permit.
  • Yeah I considered power wall earlier but it just doesn't justify the cost.
    The only benefit of it is I still get power during black out but other than that I don't see any benefit.
    Maybe you can shine some light to me?

    Solar roof on the other hand is a different story because we need to replace our roof and getting solar roof is actually cheaper than getting a new roof + solar panel. Plus it looks better too.
  • Solar panels or roof is a no brainer as you probably would get your money back within 5 to 6 years and then free for life pretty much. Battery takes at least 10 years to recover the cost but I look at them as insurance for power outage as I have temperature controlled wine storage that I could lose tens of thousands dollars resulting from cooked wine if power goes out for an extended period of time. Another reason is quite practical, when you get lots of solar energy from 11am to 3pm, you are sending excess energy back to PG&E at mostly cheap rate, but for some people, your solar production would be low after 4pm, and you need to cook and what not from 4pm to 8pm or so, that is when you might need to buy energy from PG&E at higher cost. As a very crude and may not be too accurate example, you may send 12 kWh to PG&E at 20 cents per kWh but buy back from PG&E at 45 cents per kWh during peak rate. But if you have a Powerwall, you can store excess solar energy in the battery which you can use during the peak hours and into the night or even to morning before the sun comes up. I am by the coast so sometimes there could be cloudy or foggy days so I opt for 2 Powerwalls even though one would probably fit my need, but I would have less concern on foggy days or whether I need to charge my car or bake extra batches of cookies.
  • The PG&E rate structure evolution over time is to devalue excess production and define peak rates in non-productive solar time periods. The current rate structures have peak times (and peak rates) starting late afternoon and pushing well into the evening. Depending on your schedule - peak and near peak rates are from 3 or 4pm until 9pm or midnight. Your actual peak production times are roughly 11am to 4pm. So your actual production mitigates only off peak consumption. It's the PG&E "gotcha" move. Having batteries allows you to power your home from stored solar during the peak period and then recharge the batteries the next day to cycle again. The various peak rates are roughly $0.40 to $0.60 per kWHr. Near peak is generally cheaper by about $0.10 and the off peak run roughly $0.15 to $0.30. Exactly what rates and times are defined by your rate plan.
    They put you into a "buy high, sell low" cost exchange. Advantage PG&E. Make no doubt about it - PG&E is not in a generous mood. They are not your friend.
    If you install batteries - you can essentially eliminate peak charges and sell solar at peak rates back to PG&E and your purchases will all be at the lowest off peak rates.
    For me - it means I have only a "connection fee" to pay each month and they actually send me a check for my peak production at the end of the year. Without batteries - I would get a bill every month because of the "buy high, sell low" position of pure solar.
  • Alright that give me a reason to consider powerwall.
    Maybe I will do that after my solar roof installation.

    Thanks for the feedback guys!
  • If you add PowerWalls now - my impression is that it pushes you closer to the front of the line. Naked solar or naked powerwall installs are closer to the back of the line. That was certainly the case for my son - he had existing solar and ordered three Powerwalls in October/November of last year. His install was last week. Check with your advisor...
  • Will ask my advisor during my upcoming assessment.
  • if you add powerwalls you'll have to go through the permit process again. That is what my advisor told me. Good thing is you save $1,000 by combining the powerwall with the solar system.
  • ...and doing them together makes claiming the tax credit for the PWs a near no-risk proposition, as the whole project supposedly qualifies.

    There's some question as to whether PWs can get the Federal tax credit if installed as an add-on, later. It's been interpreted both ways. My 5kW PV install was in 2015 (under Solar City), with the higher tax credit. I installed two PWs in early 2019, and claimed the credit with the same tax form as for PV. It went through with no problem. Now, would it survive an audit? I'm not certain, with the odds of a tax audit very low, but not zero.
  • I have a feeling that you are quite comfortable with your as-configured system without Powerwall even though you can use a little bigger system or maybe even a Powerwall, if that is the case then you should go for the install this year. There is a diminishing return for a bigger system with battery for you and the balance is intangible, would you feel better from not relying on PG&E or guilt-free use of electricity?

    Tesla and everyone would tell you about potential tax credit but everyone will tell you to talk to your tax accountant as no one wants to be responsible. But according to NREL you should be able to add the Powerwall next year and get 22% tax credit as long as your Powerwall is being charged 100% by PV, you will lose the 1000.00 discount but your solar roof tax credit for this year may make up for it. PG&E would not let you charge your battery from the grid unless during storm watch so that is a grey area, but if you want to be sure you can turn off storm watch then IRS cannot say anything though I doubt if they would even contest. I suspect everyone that turns on storm watch still deduct the full tax credit.

    Just do what is right for yourself but make sure you do not have buyer remorse later.
  • Thank you guys. I decided to go forward with my install.
    Will see how my bills goes and see if I needed the power wall next year.
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