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  • GoingElectric
    Solar Fanatic
    • Jun 2022
    • 120

    Questions to ask a Solar Installer company

    Researching what I need to know to make a wise pick (IF I want to install, JPM has pointed out sound economic reasons home PV may not be wise), I am formalizing a questionnaire to ask PV installers.
    Welcome anyone to add, change, rip, praise, etc

    Design:
    Sun Hours per roof face (could include Tilt and Azimuth of roof and minimum degrees from perpendicular to sun)
    System size (based on panels)
    offer multiple configurations, including the smallest system they will build
    Estimated system production
    Offset of annual electrical use

    Equipment:
    PV panel data sheets (make, model, etc)
    Microinverter / Optimizer / Inverter data sheets
    Mounting system (racks, studs, etc) data sheets
    —sub group is cosmetic items like skirt that will degrade performance (ask to remove).
    Connection / combiner / controller box (between PV and Breaker box), could include empty junction box.
    Network (cellular, Ethernet (ideal), Wi-Fi (least ideal))
    System performance visible
    Conduit and routing
    Ethernet cable run (if requested, I would)

    Install services:
    Permitting (HOA, Municipal, Utility)
    Connections (interconnections, testing, networking)
    Account setup
    Roof rebuild (if the roof needs reroofing)
    Suggested power companies (if applicable)

    Warranty service:
    Parts
    Labor
    Roof coverage
    Account and network support (aka member care)
    How fast is response?

    Financing:
    PPA: RUN AWAY, FAR AWAY, DO NOT LOOK BACK!! (Never get PPA!!)
    Loan:
    something else?

    Guarantees:
    Is there a minimum production / power generating guarantee? (Should have no issue making one)
    Other type?

    and the big ones:
    Cost:
    System cost Gross
    System cost after incentives and discounts
    $/watt
    Power bill estimate with PV (utilities will charge something even if the electricity is 100% covered all year)
    Possibly an ROI estimate

    Thoughts???


    Also include here solid advice JPM posted in other topic and copied over here.
    (PS: I did read the relevant part of Dummies book, PV for home section was not that big, went though it pretty quickly)

    1.) Do not lease or PPA - Ever - or under any circumstances. They are traps. You will regret such a decision. Especially Vivant and Sunrun who were both bottom feeders before they combined, along with SolarCity that got incestually swallowed by Tesla.
    2.) Learn about energy conservation first and PV second before you do anything else. Then, estimate use reduction from those efforts before sizing any future PV.
    Not using energy is far and away more cost effective than throwing expensive PV at an electric bill that can easily be made lower (and the PV smaller = less $$ BTW) by lifestyle adjustmants and energy conservation measures before any PV installation.
    3.) If you truly want unbiased knowledge, buy a copy of "Solar Power Your Home for Dummies" and read it before you commit to spending money. ~ $25 - cheap. You need an education. It'll give you the basics. Then, if you want insight and feedback, come back here and fill in knowledge gaps your self education creates. Besides, your questions will then have more meat on them. You'll get out what you put in. Spoonfeeding gets you pablum.
    4.) If your thinking about a roof mount - which is common - get your roof inspected and serviced before you commit to any vendor. PV on a roof can last a long time. Chasing a leak is never easy. Under an array it's nearly impossible. Give your roof a high probabilty of lasting as long as the array on it.
    5.) After your self education as described in 3 above, if you do commit to PV, go for a quality install, and that means a quality local vendor who's been a licensed, local electrical contractor who's been in business at least as long or preferably as long as PV has been popular. Know that solar vendors are dropping like flies. Established long run electrical contractors who also sell PV are probably your best bet at having a vendor be around in the future.
    6.) Spend as much or more time and effort evaluating vendors as you do equipment (which is mostly a commodity these days anyway).
    - Have the goal of most bang for the buck with overall quality in mind, not low initial price.
    - Buying low buck is the errand of shortsighted fools. Especially with something as expensive and isolated as rooftop PV.
    - Negotiate tough but fair - and remember - everything is negotiable.
    - Vendors are in business to make money by putting PV on your propery, not necesarily by lowering your electric bill. Still, vendors need to make a profit.
    - Don't fall for the price matching game. It's a trap for suckers. You'll only pay more if you fall for it. Think about it from the vendor's perspective and you may understand why.

    Welcome to the neighborhood and the forum of fewer illusions.

    Take what you want of the above. Scrap the rest.
  • GoingElectric
    Solar Fanatic
    • Jun 2022
    • 120

    #2
    Something forgot to add
    Ask what is minimum height of panel above roof (minimum is 3” (75mm), but 5+” (125mm) is far better.
    Also ask if possible to tilt to different angle than roof it is on.

    Comment

    • J.P.M.
      Solar Fanatic
      • Aug 2013
      • 14925

      #3
      As a general comment, and not that they are poor questions at all, but many or most of those questions are of the type a savvy customer really ought to have the answers for before asking them of an installer - if for no other reason than to find out what perspective installers do (or actually don't) know during the interview/weeding out process.

      Such things as likely annual or period irradiance on proposed array locations and orientations (rather than "sun-hours") are readily available as long term estimates from models such as PVWatts.
      Have you set and defined your project goals yet ? Write them down with specifics. Every project needs at least one specific goal, often several.
      Have you done a preliminary design yet ? If not, read the rest of the dummies book, even the parts you believe are not pertinent, get your project goals in place and get familiar with PVWatts. PV design is not rocket science, but it does need some structure.
      A lot of your questions can be answered by your self education.
      Those specific details that remain as questions can be answered by a good installer.
      The best project outcomes usually happen when an informed, self reliant and self informed customer finds a quality installer.

      Comment

      • peakbagger
        Solar Fanatic
        • Jun 2010
        • 1561

        #4
        IMHO - Give up on panels installed at other than roof angle. That gets you into a far more expensive engineered support structure. If you are in a wind zone, standard array supports will limit on how high you can go off the roof deck.

        Installers that are competitive have standardized on a small number of standard components that can maximize how many arrays they can install. This means they can buy in bulk and limit how much space they need for inventory. They can use standard tools to assess the roof and see what they can install with their standard inventory. Estimating future usage and PV production is just an educated guess and its how much of margin you are comfortable as weather conditions will vary year to year which will vary output. There is also fairly standard issue that pops up where if power is "free" people use more of it, so past usage may not line up with future usage. For others, they get obsessed by the numbers and cut their usage.

        Do spend some time with your local tariff for PV, it can make a lot of difference on right sizing a system. Pay attention to how long its guaranteed as political winds can change significantly impacting potential revenue from a PV system.

        If you are in a SREC state, there is an additional questions to ask, who owns the SRECs? (or other production incentives). Some installers would set up a system for SREC sales and keep the SRECs revenue for themselves.

        Comment

        • kimo
          Member
          • Jun 2012
          • 35

          #5
          Originally posted by GoingElectric
          Something forgot to add
          Ask what is minimum height of panel above roof (minimum is 3” (75mm), but 5+” (125mm) is far better.
          Also ask if possible to tilt to different angle than roof it is on.
          I am curious why a few inches panel height above roof makes a difference, what does this effect? thanks

          Comment

          • J.P.M.
            Solar Fanatic
            • Aug 2013
            • 14925

            #6
            Originally posted by kimo

            I am curious why a few inches panel height above roof makes a difference, what does this effect? thanks
            Panels flush to a roof is not a good idea for several reasons, but low, non flush clearance is probably not a good idea either because it will reduce air flow beneath an array. The more clearance, the more air flow.
            The more air flow the lower the temp. difference between the ambient air and cells, and so lower cell temps.
            Decreased PV cell temp. will increase the system's instantaneous efficiency so it'll produce more electrical energy.
            Higher temps. will also not be good for electronics which tend to last longer with fewer problems when not operated at higher temps.
            It's also easier to see what's going on under an array with a bit more clearance.
            Once you get beyond about 15 cm. or so of free space the decrease between ambient air temp. and cell temp. doesn't change much, but greater space doesn't hurt for observation or some access. My array is ~ 28 cm. and I can actually get under it if need be.
            Last edited by J.P.M.; 06-18-2022, 03:54 PM.

            Comment

            • kimo
              Member
              • Jun 2012
              • 35

              #7
              I will ask my installer about the clearance. Im getting a new PV system installed soon.
              thanks for explaining this!

              Comment

              • J.P.M.
                Solar Fanatic
                • Aug 2013
                • 14925

                #8
                Originally posted by kimo
                I will ask my installer about the clearance. Im getting a new PV system installed soon.
                thanks for explaining this!
                Assume the installer will tell you whatever is necessary to make his life easier and more profitable.

                Read this thread and others before committing.

                Comment

                • peakbagger
                  Solar Fanatic
                  • Jun 2010
                  • 1561

                  #9
                  IN my case in high wind zone, I had to pay extra for 6" clearance from a 4" ( I think it was for an extra column of supports) and they did not offer 8" due to potential uplift issues. No doubt a PE could have come up with a custom design with more clearance.

                  Comment

                  • J.P.M.
                    Solar Fanatic
                    • Aug 2013
                    • 14925

                    #10
                    Originally posted by peakbagger
                    IN my case in high wind zone, I had to pay extra for 6" clearance from a 4" ( I think it was for an extra column of supports) and they did not offer 8" due to potential uplift issues. No doubt a PE could have come up with a custom design with more clearance.
                    One of the features I designed into my array was the ability to get under it. I used 7" Unirac posts. I think they each cost about $4 US more than the 3" posts.
                    Between that extra height and the clips I used that had one longer side I managed to squeeze ~ 11 1/2" of clearance top of roof deck to bottom of cells. It's a tight fit but as long as I keep my BMI low I can squeeze under the array if need be. That came in very handy when I was measuring cback of panel instantaneous temps of all the panels with an IR thermometer and comparing them to simultaneous string voltages over about a 6 month period.

                    I did my own external load check of my own array which I did the mechanical design for, but since I had retired my license several years before that, I wasn't sure I'd need an additional P.E. signoff/check. I showed the AHJ what I did about wind/seismic loadings that were per ASCE 7-86 latest ed. and they gave me a pass on it. Point is, as long as the array is parallel to the roof and the standoff is - in the engineer's judgement - "reasonable", I don't believe any considerations for larger aspect ratios are necessary such as would be required for tilted arrays for example. However, I'm not completely up to date on ASCE external loadings and things may well have changed over the last 9 years since I did my design, particularly with respect to edge effects of wind loadings for arrays close to roof edges and for aspect ratios.

                    Comment

                    • peakbagger
                      Solar Fanatic
                      • Jun 2010
                      • 1561

                      #11
                      I am a PE in NH with no stated specialty, ultimately, I need to be "competent" in whatever engineering I do, I was not comfortable with the available information on wind loading design for uplift and thus I stuck with commercial system that if there was any question, the manufacturer owned the liability. Its a small roof array (2 rows of 4 panels) feeding a string inverter so access under the array is not that difficult. In the case of my pole mount I applied "formula P" and added more pounds of steel. I also have external wind braces that I added to reduce twisting. If it fails there is nothing of value downwind. Having dealt with commercial roofs damaged by wind uplift I have seen the potential damage and decided that I did not want to risk it on my roof as if could make my home unlivable should a high wind occur. (I do live about 5 miles north of the point where the second highest wind velocity on the face of the earth was recorded)

                      Comment

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