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DIY solar: Looking for information?

AndrisSkulte | Posted in General Questions on

Is there a similar forum to GBA or JLC that has good discussions about solar?

Now that the four 1:1 mini-splits are installed and we’ve upgraded to 200A service, my next project is to add Solar (PV) to our house. We’ve gotten quotes from a few big name companies, and the mark-up is insane (seems to be 100% above mail order hardware cost), so I’m considering doing it myself. I’m very comfortable with design, engineering, and construction. It’ll take many lunch breaks and evenings to learn about the local utility (Eversource in Connecticut) installation requirements, as well as getting familiar with the different products out there.

I’m looking at a 7.5 kw grid-tied system, likely with 315+ watt panels since we’re limited to the less shaded roof over the garage. Hardware cost seems to be about $11k online for systems like this.

The install looks similar enough to other electrical and construction work, and doesn’t seem intimidating, and I’m having a hard time seeing the value of a 100% mark-up (quotes all came in at $25k+, but they justified it based on the fed and state tax credits). I’ll likely do the bulk of the work, and have an E1 electrician friend of mine do the final review/connection for the utility.

Connecticut’s net metering law that grand-fathers us for 20 years expires at the end of this year, so there is a bit of urgency. 

Energize CT has a page here that discusses small solar, and even a spreadsheet with $/kw install costs… Some are down to $2/kw, but those seem to be leases where the companies don’t charge as much to their customers.

Thoughts?

https://www.energizect.com/your-home/solutions-list/residential-solar-investment-program

Spreadsheet Link: https://www.energizect.com/sites/default/files/Copy%20of%20Data%20for%20Web%202019-05-31.xlsx

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Replies

  1. user-3258290 | | #1

    I did all aspects of a similar size system myself last year. It takes some effort to digest the codes enough to discern what setbacks are required and the specifics of what grounding rules apply in NEC whateveryear. Selecting components is easy enough, since there are plenty of self-grounding racking options to pick from and 60-cell modules are ubiquitous. There are readily available one-line diagram templates and examples of the roof drawings and diagrams you'll likely need.

  2. Expert Member
    AKOS TOTH | | #2

    I've done DIY system here for similar reasons as you. I think the reason for the upcharge is that each install is always different, contractors want to cover their behind in case some annoying details pop up.

    Except for the fact that you'll be working at height, there is nothing too challenging in the install. Micro inverters are much simpler to install and work better if there is any amount of shading.

    With your 200A panel you are limited to 7.6kW of inverters, which is above the amount of solar you'll be installing anyways.

    1. insaneirish | | #6

      > With your 200A panel you are limited to 7.6kW of inverters, which is above the amount of solar you'll be installing anyways.

      It’s been a little while since I’ve reviewed the code on this, but I believe this limit is if you are feeding into the panel via breakers in that panel. (The theory being that you can actually put more load on the bus bars than they’re rated for if you pull the full 200A from utility plus full capacity from inverters.)

      A way around this is to a line side tie in (i.e. between your meter and main disconnect/breaker). By doing this, there’s no chance of ever pulling more than 200A into the panel bus.

      1. Expert Member
        AKOS TOTH | | #7

        Yup. There is many ways of skinning that cat if you need more than 7.6kW. The simplest is downsizing the main breaker, unless you have two electric cars charging, very few houses would use much above 100A.

        The panel manufacturers now make special panels that have the side tie in built in specifically for this reason. Search for solar ready panel.

        1. user-3258290 | | #9

          > unless you have two electric cars charging, very few houses would use much above 100A.

          For reference, my house with an electric water heater, EV charging station, two heat pumps, electric dryer, plus lighting and things means my "electrical load" is ~180 A, enough that I cannot switch to an electric range without upgrading to 400 A service. Resizing the main breaker isn't a great long term approach, because it limits the opportunity for decarbonizing your house down the road.

          1. Expert Member
            AKOS TOTH | | #12

            I had the load calcs for an all electric place here with a 24kbtu mini split. If I add in a 48A demand for an e-car, only coming up to 127A. Maybe a difference because it is Canadian code.

  3. AndrisSkulte | | #3

    Keith - Thanks. Eversource has a checklist for solar permitting which seems straight forward. I'll have to check online to see if any of the one line schematics fit. I assume they would, or if one is is included buying a system from some place like wholesalesolar, renvu, or solarelectricsupply.com.

    Also found about the https://www.solarpaneltalk.com/ forum from this GBA thread:
    https://www.greenbuildingadvisor.com/question/why-solar-since-net-metering-is-over

  4. user-3258290 | | #4

    Unless you really need the kit to simplify things, you'll probably do much better on cost buying localish from CED Greentech or similar.

  5. joenorm | | #5

    I do PV installs as a profession and I highly encourage DIY. I'd recommend a Micro Inverter system over anything else as a DIY. Simplifies the code questions a bit and you don't have to deal with higher voltages and string sizing.

  6. Jon_R | | #8
  7. AndrisSkulte | | #10

    Fantastic stuff - Thanks guys! Jon - I'll check out the https://forum.solar-electric.com forum.

    Joe & Akos - Micro inverters seem like the logical option. I do have some partial shading, so optimizers or micro's are a must. I didn't really how polarizing the SolarEdge vs Enphase discussions could be (the other forums and reddit). I like the idea of being able to generate power during a blackout, so an inverter that can create a temporary micro grid would be nice to have (Enphase Ensemble, SunnyBoy)

    I found "Mark's Blog" from MC Electrical, who seems pretty candid about the products his company uses, along with reviews - https://mcelectrical.com.au/blog/ Reliability wise, he's a fan of the TIGO TS4 optimizers with a basic inverter like Fronius or SMA SunnyBoy.

    I need to check my garage roof truss size/spacing to make sure it can handle the extra load.

    Akos & Keith - I need to check what the new GE panel bus is rated for. I might have a 200A main breaker on a 225A panel. Using the 20% bus oversizing factor, gives 270A total bus current, so theoretically could I feed the solar back to the panel through a 70A breaker and get 16.8kw (yeah, I know, no derating included)... I'm hoping that would give plenty of head room. If not, I could always downgrade the main breaker to 150A...

    Keith - Thanks for the CED Greentech suggestion. We're slowly converting to all-electric, and even with our largest loads going, we haven't been over 100A this summer. I'll wait to see what winter brings with the mini splits instead of the oil burner... Electric car may be the next vehicle a couple years down the road. And a hybrid hot water heater. In the meantime, I've got a full 275 gallon oil tank in the basement to use up for hot water...

    Does anyone have preferences for racking or installation tools to speed things up? It's going on an asphalt shingle roof. Shingles are about 15 years old. Since I'm DIY, I was thinking of installing on top, rather than re-shingling, and R&R the panels when it's time for a new roof... Pitch (eyeballed) is a 4/12, and the garage end wall is only 6' high at that point, so not hard to work there.

    I already have a 60A sub panel in the garage, which ideally I'd feed from the solar and save 50' of duplicate wiring back to the main panel. I need to look into grounding requirements...

    Anyways, thanks a lot for the suggestions!

  8. GBA Editor
    Brian Pontolilo | | #11

    Hi Andris,

    I'm not sure when you plan on doing this work, but we are planning to take a look at racking systems in an upcoming GBA article. It may still be a month or two before it is published though. In the meantime, check out this FHB article. The Iron Ridge racking system is pretty slick. I was onsite for the install shown in the article and came away feeling like it was a project I'd feel mostly comfortable doing myself.

    Installing Rooftop PV

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