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Solar system doesn't make sense for our house / electrical usage?

Discussion in 'Tesla Energy' started by BrokerDon, May 3, 2019.

  1. BrokerDon

    BrokerDon Active Member

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    Good News: Our roof is almost perfectly south facing, we can pay cash for a solar system, and we can use every bit of the projected $11,000 Federal Tax Credit.

    Bad News:

    IF
    we install solar we will only install it on the portion of our roof that isn't visible from the street. This restricts the number of solar panels to 19... which optimum system designs (6.6kW) have mandated more expensive 345W or 360W panels. This combined with our need to replace our completely stuffed 200A main service panel with at least a 225A "solar ready" MSP and challenging Spanish clay tile roof (needs to be "picture framed) yielded this quote from SunPower 2 years ago:

    19 X 345W: $33,268
    225A MSP: included
    Roof Work: 2,850
    Total: $36,118

    Pre-Tax cost per Watt: $5.51
    After-Tax cost per Watt: $3.86

    ... and recently this $29,690 quote from SolarMax for a 7.26kW system with 22 LG 330W panels (no MSP upgrade... and honestly i don't think they can install 22 panels where they think they can)

    Pre-Tax cost per Watt: $4.08
    After-Tax cost per Watt: $2.86

    The issue is our SCE TOU-D-B-SDP bill only runs $80 per month (summer) to $200 per month (winter) for 800 kWh to 1,200 kWh per month on our 3,300 sq. ft. 2-story single family home in Newport Coast CA:
    • 120 to 140 kW @ 25¢ kWh On Peak (2 PM to 8 PM)
    • 300 to 400 kW @ 15¢ kWh Off Peak (8 AM to 2PM + 8 PM to 10PM weekdays + 8AM to 10PM weekends)
    • 500 to 800 kW @ 10¢ kWh Super Off Peak (95% Tesla charging 10PM to 8AM every day)
    I'd really like to add solar but the R.O.I. is way too long... past my expected life expectancy since I'm almost 65. 8-(

    Almost every solar company (including Tesla, SunRun, etc.) refuses quote because we have a Spanish clay tile roof (needs to be "picture framed).

    Am I missing something?
     
  2. P85_DA

    P85_DA Supporting Member

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    That’s looks about right I did same calcs and with EV TOU plans in Socal it just a matter of putting everything on a timer an scheduling large items at night car, washer , dishwasher ;)
     
  3. BrokerDon

    BrokerDon Active Member

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    That's exactly what we did when we moved into our home ~ 10 years ago. We installed Wiser Energy smart plugs on every load we could "time shift" and do all our laundry during "Off-Peak" (doing laundry before 8AM and after 10PM during "Super Off-Peak isn't worth the effort). SCE's Summer Discount Plan saves us ~ $500 for the 4 summer months it runs and is only a minor inconvenience since we live by the coast.

    Being super energy efficient and Time of Use aware has made adding solar a poor investment so far. :(
     
    • Like x 1
  4. P85_DA

    P85_DA Supporting Member

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    Agree ... I forgot to mention I have 2 zone AC on Nest thermostats and they also do good job in summer as I have them connected to the electric company alerts it will cool in advance of peak periods
     
    • Like x 1
  5. Uncle Paul

    Uncle Paul Active Member

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    With your high costs of installation and relatively low $80 Summer bills a Solar installation will rarely pencil out.
    If you can convert to time of use, perhaps a battery storage for time shifting might work better.

    Perhaps the most cost effective energy saver might be a whole house or quiet cool whole house fan. Can bring in cooler air in the evenings to pre-cool your home for hotter days, or bring in warm daytime air to warm up the house in preparation for the cooler winter evenings.
     
    • Informative x 1
  6. mswlogo

    mswlogo Active Member

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    First $5.51 /watt is outrageously high. Tesla just announced $2.85 /watt BEFORE Tax breaks.
    Also as far as calculating your new service panel, you should not factor that into your ROI.

    I had a "stuffed" modern 100A panel and they added 8000 watt system fine. They "Tapped the Main lines".
    If you want a new Panel, fine, but don't factor that into your ROI and skew the numbers.

    The roof is an issue. Then get it picture framed first so you can get more reasonable quotes.

    You could also consider a Power Wall to shift some of your usage but those are not easy to get good ROI on either.
     
  7. Haxster

    Haxster Member

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    Other factors to consider are:

    Positive...
    Possible portion of the cost recovered if you sell your home.
    Projected increases in utility rates (but stable sun output) the future years.
    Helping to save the planet

    Negative...
    Maintenance/repair costs, and output degradation over time
    Roof leaks more likely and more costly to repair.
    Another little addition to life's complexities
    Appearance

    Every few years I look at the economics of going solar. I like the concept and monthly savings. But it just doesn't make economic sense for our situation....even with high PG&E electricity rates.

    However, just for fun, and with a likely negative ROI, I DID add a 10W solar panel to our 12V gate opener/12V "power grid".
     
  8. BrokerDon

    BrokerDon Active Member

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    We have Ecobee smart thermostats with additional sensors in each of the 4 rooms we typically use. They're awesome and have made our house more comfortable AND less expensive to heat AND cool too!
     
  9. mswlogo

    mswlogo Active Member

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    #9 mswlogo, May 3, 2019
    Last edited: May 3, 2019
    Degradation is pretty darn low with good panels. I’m 4 years in and see none so far. Installer company / manufacturer will handle any repairs for 20 years (or was it 25, I forget). They will remove replace panels for free if the roof leaks. There is absolutely zero maintenance.

    My personal ROI is 6-7 years. Then I make a profit for 3-4 years. This was an incentive program that is not available to everyone. But it made it a no brainer to sign up. I know some states with even better incentives. After that it’s net zero for at least 10 years until warranties run out. By then there should be something even better.

    If the ROI was 20 years because lack of incentives I’d do it in a heartbeat. I need to at least break even over the life of the product.

    Electricity has gone up ~12% since it was installed which accelerates the ROI.

    A friend did a lease deal. His electric bill was cut in half. And it’s guaranteed even if his solar doesn’t product due to weather or repairs. He’ll receive a check from them to pay his electric bill if it falls short. He paid $0 and they completely upgraded his service panel. But if he sell his house he needs to sell the new owner the “lease” which might not be attractive say 10 years from now. I think after 20 years the system is his.

    I think one rule of thumb is, if you pay more than $0.08 a kWh then it’s worth going solar. Because that’s what solar electricity costs when you amortize it over 20 years. It depends partly on your sun exposure. Better exposure requires less panels for the same watts. My exposure was less than ideal.
     
  10. RFernatt

    RFernatt Solar/EV Owner/Enthusiast

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    Add an EV or two to get more bang for the solar buck? Presuming you drive a fair bit, don't already have an EV, and we're interested in buying an EV regardless.
     
  11. mswlogo

    mswlogo Active Member

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    But he is capping himself on Solar capacity because he doesn't want it to be visible from the public view.
     
  12. BrokerDon

    BrokerDon Active Member

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    We're already driving ~ 95% of our miles in our Tesla. Our Prius is only used when I'm in our Tesla and my wife needs to go somewhere else... or to move the Tesla from our driveway every couple of weeks to keep the rodents from building nests inside. Seems our Prius is a great "safe space" for squirrels and rats.

    The other problem with adding more EV consumption is our EVs charge during "Super Off-Peak" at 10¢ per kWh which is at best slightly more than the < $1.99 per Watt After-Tax solar systems... but definitely less than our $2.86 to $3.86 per Watt After-Tax cost. 8-(
     
  13. BrokerDon

    BrokerDon Active Member

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    True... but even if we put 2 panels on the one section that's visible from the street so we could use cheaper ~ 330W solar panels like the 2nd proposal above our cost is still $2.86 After-Tax cost per Watt... and that's without upgrading our completely stuffed main service panel.

    My only other thoughts were to:
    • scale the system down to trim off the 25¢ / kWh On-Peak and 15¢ kWh Off Peak usage with solar... but that increases the fixed cost of our installation over fewer Watts. Catch 22
    • increase our electrical consumption by running our AC more in the summer... but that seems counterintuitive
     

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