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  • J.P.M.
    Any PVWatts modeling is without shading unless you plug in an estimate by modifying the system loss parameter.

    I'd invest in a chain saw and get rid of the trees, but that's opinion.

    From the cartoons, and depending on their height, it looks like some of the roof penetrations may shade some of the array. Perhaps more importantly, if the first cartoon is correct in its roof penetration locations, the Sunpower cartoon will have has panels either covering vents or the vents assumed moved. Covering vents is not a good idea.

    Help avoid the Dunning-Kruger syndrome by getting good and straight information that'll filter the hearsay and conflicting info from unvetted sources - usually with skin in the game. Start with a free download of a slightly dated version of " Solar Power Your Home for Dummies"., or a new hardcopy version for ~ $25 @ bookstores. Learning buzzwords and anecdotal junk without a grasp of the basics is like trying to get into an elevator that's already gone up 5 ft.

    Leave a comment:

  • Mike90250
    It looks like several trees near the house have to go.

    Also, I would do the meter upgrade "critical Loads " panel

    Leave a comment:

  • CycloneFW
    started a topic Newbie to solar gotchas?

    Newbie to solar gotchas?

    As many topics in my search start, “I’m a newbie to solar”. I understand the basic concepts and have a decent handle on it, but you don’t know what you don’t know and I want to make sure I’m not suffering from the Dunning–Kruger effect, knowing just enough to be an idiot!

    Anyways, I am located in NC and looking at grid-tie with net metering to Duke Energy. I’ve gotten five quotes and have decided which one to go with, unless something/someone tells me to run screaming.
    - Local installer
    - 28 x Solaria PowerXT 360 panels
    - SolarEdge SE10000H inverter with P370 optimizers, including consumption meter
    - IronRidge XR-100 with FlashFoot2
    - Installation mid-to-late August
    - Net metering start would be after October 2nd to qualify for utility rebate ($0.60/W up to $6k)
    - Shading is a concern
    - Estimated production 10,500 kWh/year
    - Retail cost $792/panel fully installed, net cost $10,500
    - 25 year parts/production/labor warranty from Solaria
    - 25 year SolarEdge warranty (extended on inverter)
    - 20 year labor warranty by installer
    - 3 year production guarantee within 10% of estimate - guaranteed by check or additional panels to make up difference

    First image is this panel install proposal. Second image is from another installer using SunPower panels.

    The one tree behind the garage has to go. The cost is not included in the quote above. I’ve wanted to remove this tree anyway, as it has grown over the house and has been trimmed back twice before. Getting quotes over the next week for this removal.

    My electrical panel likely will need an upgrade, unless we do a load-side tap. 200 amps of service, 200 amp split bus bars. Every 120v circuit except for two are already tandem and no open spots available.

    Electrical panel is in full size basement that stays low humidity and 70*F-ish year-round. Plenty of adjoining wall space to mount inverter. Meter on other side of the wall. Installer has in-house electrical engineer and if upgrade necessary, +$1,600.

    On-site visit for photos and measurements will be next week. Then in-house engineer will design system / plans for my sign off. Paid $500 refundable deposit already. Becomes non-refundable once I sign the plan. All but 10% due once install is complete, remaining 10% due when system is running and all permitting & permission to operate complete.

    Oddly, the installer said “Between initial installation (August) and final activation with Duke (October) you are still able to generate and use your solar power on-site. The only thing you can't do is sell excess power back to Duke (until you fully activate in October).” I don’t understand how that works.

    I’ve punched my info into PVWatts and it said something around 15k kWh/year. I didn’t see how I could put in that the tree would be removed. I put in some production discount and it provides a 13.5k kWh/year estimate. The panels would be installed on the southwest facing side of a 7/12 roof.

    This is a 100%-electric house using Duke’s RE rate schedule for basically $0.08 kWh. Annual electrical use 2018 - 2019 was 19.5k kWh, 2019 - 2020 is 17.5k. This includes charging an electric vehicle. Single zone heat pump, two climate controlled floors + full size basement.

    Are there any gotchas I should keep an eye out for? Anything in specific I should ask to get done/added? I am happy to answer questions/provide feedback. Please note that cost/value is important, but personal desire also plays a role. So if my back-of-the-envelope math of a 12 year payback is correct, I can live with that. Wish is was under 10 though!
    Last edited by CycloneFW; 07-17-2020, 08:49 AM. Reason: Correct typos