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Solar in Seattle/Eastside

Discussion in 'Northwest' started by romp, Oct 2, 2014.

  1. romp

    romp Member

    Joined:
    Apr 18, 2014
    Messages:
    91
    Location:
    Seattle
    We started to think about installing solar on our roof. We have a ~45'x25' south-east-facing roof plane at about 30 degrees inclination, seems to be good enough for an average size installation.

    Can somebody recommend any installers? What are approximate installation costs we should be expecting (ballpark)?

    Theoretically, we should expect about 2.4 kWh/sq.m/day at this plane (given 3.55 kWh/sq.m/day at latitude tilt according to this map http://www.nrel.gov/gis/images/map_pv_national_hi-res_200.jpg). Assuming 15% efficiency of the panels, we hope to be looking at about 35-40 kWh/day on average. Are those realistic numbers?

    BTW, looks like we're in the worst part of the lower 48 solar-wise. AZ and NM get almost twice the amount of energy we get.
     
  2. EchoDelta

    EchoDelta Member

    Joined:
    Mar 5, 2012
    Messages:
    732
    Location:
    Seattle, Planet Earth
    Hi Romp -
    By recommendation of other forum members we worked with Sunergy Systems. I was super happy with the process.

    It would have made total sense for us were we not neslted deep behind some firs and maples that get the best of our rooftop sun during most of the day. I *almost* built a carport just to hold panels but we may be moving anyways.
    Prices varied mostly based on how many KW you want installed and the source of converters and other gear (made in-state is more expensive but qualifies you for more incentives- at peak with net metering we could have obtained $0.40 from PSE with net metering!).
    Many kWh are possible if you have enough panels :) Summer and winter will also vary.
    YMMV, but if I recall correctly they were touting rules of thumb to approximate production that more or less yielded that in this area 1kW of panel equates to roughly average 1kWh/d of yield. Others please correct me based on your actual numbers.

    I would have liked SolarCity but given the first survey results and that it was early for them in this area still I didn't push.
    We are a family household with 2 adults and 3 kids in the house all day and we use up around 20-22 kWh/d excluding car charging.
     
  3. brianman

    brianman Burrito Founder

    Joined:
    Nov 10, 2011
    Messages:
    15,487
    I wanted to go with SolarCity (even more now with the battery option...) but the extend of their reach in WA was/is to install my HPWC.

    I went with Solterra.
     
  4. ChadS

    ChadS Petroleum is for sissies

    Joined:
    Jul 16, 2009
    Messages:
    2,401
    Very rough numbers:

    My house came with a 9.75kW system, but on a smaller 21 x 25 roof (about half the size of yours) I'm currently adding 4.86kW system (that includes rooms for setbacks around the edge of the roof; it's not really stuffed full). I've seen suggestions of a 1.1 rate for this area, but my installer (and home builder that puts solar on all of his houses) suggests just figuring 1.0 even if the roof has good exposure, especially after inverter losses. So that would be 4,860kWh hour for a year, or about 13kWh per day. You should get a little over twice that if you fill your roof.

    As EchoDelta said, prices vary depending on whether they are made in WA or not, how far the lines run, how easy the roof is to work on, etc. With a ~10kW system, you will probably want them to be. Somewhere in the $40k range, maybe? Of course there are a lot of variables. It should pay for itself in about 6 years given current incentives.

    Some installers I am familiar with and think you'd be happy with:

    NW Wind and Solar: my builder always uses them, and since they did our existing system we are having them integrate our new panels with it. They have been great to work with, and my existing system is very nicely done.
    Puget Sound Solar: the owner is a Seattle EVA member and very involved in the EV community, has made his own house net-zero, and was recently featured in the Seattle Times.
    Chris Herman: he did a community solar project a few years ago that I took part in. He was a pioneer, tireless worker and nice guy.
     
  5. romp

    romp Member

    Joined:
    Apr 18, 2014
    Messages:
    91
    Location:
    Seattle
    Thank you very much for the info and links (and the PMs too)! Will probably start calling next week.

    The price is the primary concern here and I imagine this will be the perspective we'll be taking when deciding to pull the plug (pardon the pun). Our current power bill is about $180-320/mo (summer-winter), and we're on the PSE green power program. It seems that it would take longer than 6 years to offset $40K. But we understand that each case is unique and we'll do our shopping. Will report back if/what we decided to go with.
     
  6. brianman

    brianman Burrito Founder

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    #6 brianman, Oct 4, 2014
    Last edited: Oct 4, 2014
    Some calcs using Chad's SWAG...

    Code:
     $40,000 Paid
    -$12,000 Federal Rebate
    -----
     $28,000 Cost
    
    54c/kWh Production Incentive for in-state panels and inverter
    10c/kWh Savings vs. paying from grid
    -------
    64c/kWh Payback rate
    
    43750 kWh required for payback = $28,000 / ($0.64/kWh)
    
    8760 hours per year = (24hr / d) * (365 d/yr)
    
    0.83 kW average continuous = 43750 kWh / (8760h/yr * 6yr)
    
    [COLOR="#0000FF"]0.083 yearly average efficiency factor required[/COLOR] = 0.83 kW average continuous / 10 kW system rating
    
    For comparison, my 5.76 kW system production was approximately 5,000 kWh last year.

    0.57 kW average continuous = 5000 kWh / 8760 h

    0.098958 yearly average efficiency actual = 0.57 kW average continuous / 5.76 kW system rating


    (My recollection is that for my house TSRF is over 75% but not by much.)

    Using this rough calculation my system is 19% more productive than is necessary for the numbers Chad was throwing around.

    I have no idea if his "10 kW rated system installed for $40k" is currently accurate though. My system was installed a year ago and prices have moved since. My recollection is that when I bought it was an 8yr break-even point.
     
  7. brianman

    brianman Burrito Founder

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    I happen to be looking into pricing recently, so I have newer data to consider.

    The system I'm considering includes battery backup.

    So running the 6 yr calculations again:
    Code:
     $55,310 Paid
    -$16,593 Federal Rebate
    -----
     $38,717 Cost
    
    54c/kWh Production Incentive for in-state panels and inverter
    10c/kWh Savings vs. paying from grid
    -------
    64c/kWh Payback rate
    
    60495 kWh required for payback = $38,717 / ($0.64/kWh)
    
    8760 hours per year = (24hr / d) * (365 d/yr)
    
    1.15 kW average continuous = 60495 kWh / (8760 h/yr * 6yr)
    
    0.133 yearly average efficiency factor required = 1.15 kW average continuous / 8.64 kW system rating
    
    There's no way I'm getting that yearly average efficiency so it definitely won't break even in 6 years.


    But let's find out when it would break even using the efficiency of my current location...
    Code:
    0.098958 yearly average efficiency actual
    * 8.64 kW system rating
    = 0.855 kW average continuous
    
    8.077 years = (60495 kWh / 0.855 kW) / 8760 h/yr
    

    Ah but it's harder than that. The production incentive for WA runs out in June 2020. For simplicity, let's assume that means I only have 5.5 years of production.

    2.577 years overage = 8.077 - 5.5

    The overage years need to be scaled by the reduction on production value...
    16.5 yr = ($0.64 / $0.10) * 2.577 yr

    So, because the production incentive ends in mid-2020 my actual break-even point is 22 years.

    The moral of the story? The production incentive is kind of huge in the economics, and battery backup is spendy.
     
  8. EchoDelta

    EchoDelta Member

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    Location:
    Seattle, Planet Earth
    Thanks brianman - do you mind sharing which providers were able to quote storage for you, and what sizes of storages are you considering (or is size even an option/variable).
    For my main residence this won't work but looking for options for elsewhere.
    Hopefully this is not too off-topic; maybe is something OP may care about or we can all learn from.
     
  9. brianman

    brianman Burrito Founder

    Joined:
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    Solterra.

    Some links:
    - Storage
    Outback Power Inc. - Energy Storage EnergyCell RE
    - Charger/Inverter
    Outback Power Inc. - Radian Series GS8048A / GS4048A
    - Charge Controllers
    Outback Power Inc. - Charge Controllers FLEXmax 80
    - System Display and Controller
    Outback Power Inc. - Communications MATE 3

    I'm considering what most would probably consider overkill re: storage, so probably best to discuss that in PMs.
     
  10. richkae

    richkae VIN587

    Joined:
    Jan 15, 2008
    Messages:
    1,917
    #10 richkae, Oct 8, 2014
    Last edited: Oct 8, 2014
    I have a system on my house from Puget Sound Solar.
    I was very happy with them.
    I got the full "made in washington" stuff to maximize the production incentive. The system went on the house in January 2011 and should be paid for by 2019 at the latest.
    Unfortunately I have no battery backup because I talked myself out of it because of the expense and lower efficiency.

    You will be appalled at how bad your production can be in June-July because of clouding. The first 3 years my September output was better than June and July because of clouding.
    This summer may flip that, the summer was good. Of course the dark winter months are super depressing.
     

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