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  • Need some advice on a New install of Home Solar

    So, I have reached paralysis by analysis, I could use some advice pro's cons etc. My house faces directly south, two story no shade. We have 1 for 1 Net metering for 12 months then resets. 25.00 A month connection fee and a max system of 10.KWdc I have received numerous bids and options from my research to be reputable solar installers in my area.

    Main questions. Depending on panel wattage I will need between 27 and 31 panels to get to 10KW, I have bids for LG and Rec panels. The bids range from 28K for REC N series to 32K for LG 350N1's or REC Alphas I had it specd with iq7+ (possibly future proofing if that 10KW ever changes) The biggest difference between the panels is the REC N series has 25 Years 86% guarantee and the others are 90-92%

    So, does spending the extra 3-4k on better panels now gain me anything? My initial thought was Yes, I could get to 10KW with 3 or 4 less panels, but with panel efficiency's getting better every few years. I figured at current rates I could just replace a few panels with higher efficient panels to make up the losses of degrading panels. Am I missing something in my logic? Thanks for the help.

  • #2
    I do not have a crystal ball. I have no idea of which is best. In twenty years, you likely will not be able to tell the difference.
    4400w, Midnite Classic 150 charge-controller.

    Comment


    • #3
      Answers to your questions:
      - Above some basic and easy to find quality level, including the mfg's you mention and a lot of others, and in spite of what solar peddlers and the greenwash media would have you believe, panels are a commodity and have been for some time. Be much more concerned about vendor quality and integrity and how long they've been in business and know that a quality install is worth a (slight) premium fairly negotiated.
      - Also, guaranteed output is mostly good for marketing purposes and not much else. It's also nearly and effectively impossible to verify. I wouldn't worry about it. Even if it was verifiable, and even if true, a few % difference in annual degradation sure as Chit ain't worth the $4K you write of - even in NPV $$'s discounted to present worth.
      - If/When panels need replacing, it's best to replace them with panels that have the same/close operating parameters and STC rating, so you figured wrong.


      Other stuff to possibly consider if you haven't done so already/don't know, and for no more than FWIW:

      1.) If you haven't done so already, get/find your annual electric load and how much of it do you want to offset with PV.

      2.) Also, if you haven't done so already, download a slightly dated free version or spend ~ $20-$25 on an updated version of "Solar Power Your Home for Dummies". Then, get familiar with something called PVWatts. It's software for preliminary design of residential PV systems, free on the net from NREL. Read all the help screens a couple of times, get the inputs reasonably close to your location and orientation, and with your answer to # 1 above, get a preliminary size. Then get familiar with how your POCO charges you for electricity and what a Net Metering Agreement with your POCO might require as well as any requirements and/or permits your AHJ (the building dept.) may require.

      3.) If this will be a roof mount, do yourself a big favor and get your roof inspected/serviced before any PV goes on it. PV lasts a long time. Give the roof under it the best chance possible of lasting as long. Cheap insurance. Besides, chasing a leak on a roof can be and usually is a PITA. Chasing a leak under a PV array is next to impossible. The first good rainstorm and you sleep soundly, you'll have your roof inspection/upgrade paid for.

      Welcome to the neighborhood.

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      • #4
        Thank you for the replies, I had been messing with PV watts, Roof is 10 years old but inspections are good to have as you said peace of mind. Thanks for the info on keeping panels close to the same specs.

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        • #5
          I don't think there is much to gain with the more expensive solar panels.
          The REC Npeak are one the best price performance panels I can think of. I would also consider the Alpha if the space on the roof was limited and the price/watt is close to the Npeak.

          Comment


          • #6
            Originally posted by scrambler View Post
            I don't think there is much to gain with the more expensive solar panels.
            The REC Npeak are one the best price performance panels I can think of. I would also consider the Alpha if the space on the roof was limited and the price/watt is close to the Npeak.
            If you compare the output per STC kW of what have shown themselves to be reliable models of otherwise identical arrays in the same location and orientation when panels are changed, you'll find little difference in annual output per installed STC kW. That's where the rubber meets the road.

            Note also that PVWatts makes a distinction between standard and premium panels, but their descriptors of what they call a premium panel being most anything on the market at this time - meaning that PVWatts makes, in effect, no distinction between decent panels currently available which means panels model identically and so are most likely to have about the same efficiency.

            BTW, the efficiency most everyone is talking about is an AREA efficiency, meaning a more efficient panel has a smaller footprint. To a 1st approx., a panel's published efficiency is inversely proportional to it's power density as measured by output per unit area.

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            • #7
              Dollars per watt is the main criteria in choosing panels. PV panels are pretty much of a commodity and they are all amazingly durable. Don't pay extra for the high end brands unless you are constrained on roof space and really need the small advantage in higher efficiency that you will pay a lot for. Stick with any of the "tier 1" brands like Q-cells, Mission Solar, Silfab, Canadian Solar, etc and shop for the best price and you won't go wrong. Do care about the appearance of the panels. Some have obnoxious white spots or silver frames that can look bothersome to your neighbors. Get the spec sheets and see what the panel looks like.
              "Triple black" looks the best by far especially if arranged in a nice rectangular, non-patchwork array. Have your installer move some of those ugly plumbing vents if need be.
              Don't worry about the warranty. They are all about the same except some companies play games to make their product sound a bit better. PV panels rarely, rarely fail and if they do good luck getting any of the manufacturers to do much for you.
              Last edited by solarix; 04-23-2020, 11:09 PM.
              BSEE, R11, NABCEP, Chevy BoltEV, >3000kW installed

              Comment


              • #8
                Thanks guys, I appreciate the feedback. So I'm good with the panel info, So JPM, You said panels should be closely specd. So my idea of 5 or 10 years down the road, and I'm not outputting 100% of my power via solar, anymore, I can't just go and buy X amount of higher wattage panels and swap out some, Even on Micro converters?

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                • #9
                  With microinverters, you can mix panels freely. Each panel/microinverter pair acts as an independent solar generation system.

                  With that said, if you buy a 500 watt panel in 2030 and connect it to a 250 watt microinverter vintage 2020, you won't be taking advantage of the full capability of the new panel, so you'll be wasting money. It might be more cost-effective to upgrade microinverters when you upgrade panels.

                  I'm wildly speculating that the panels in 2030 will produce much more than today's panels. The trend has been upwards, but I am not smart enough to predict the future.

                  I'll also go out on a limb and speculate that microinverters in 2030 will be better in some way(s) than those of 2020. Electronics seems to keep getting better. They may get more efficient, smaller, cheaper, smarter, higher power, or improve in some other way.

                  Back to reality: it is possible that panels on the market in 2030 will be different size, different thickness, or different cell count than panels you buy today. We are seeing a general trend to thinner panels and Panasonic is selling excellent, but odd-shaped 96-cell panels. Also, if you compare the exact dimension of panels from one vendor to another, you'll notice that even very similar panels today vary in length roughly ±2cm. This can be a problem if you have to replace one panel and still want the array to look good.

                  Back to your original question. I bought panels and microinverters with the understanding that they would pay back in 5 years and after that, they will be printing money for me. If you plan to upgrade/reinvest after 5 years, your financial incentive greatly weakens.

                  Fortunately, all indications are that 10 year old panels will produce much more than 90% of what they produce when new, probably more like 93%-95%. At that point, you won't notice or care about the difference. Old panels should still be doing great.

                  A much bigger problem for me is that the trees in my neighborhood will have grown quite a bit in 10 years. It's ironic that we want to have solar panels to be green, but we need to kill trees to harvest sunlight.
                  7kW Roof PV, APsystems QS1 micros, Nissan Leaf EV

                  Comment


                  • #10
                    Originally posted by RSQ View Post
                    Thanks guys, I appreciate the feedback. So I'm good with the panel info, So JPM, You said panels should be closely specd. So my idea of 5 or 10 years down the road, and I'm not outputting 100% of my power via solar, anymore, I can't just go and buy X amount of higher wattage panels and swap out some, Even on Micro converters?
                    Micro's big advantage is that they enable production from a (partially) shaded array that will exceed that of an otherwise identical system (including shading) but string inverter equipped system (Note however, and as an aside, micros will not restore irradiance and so performance that was not there due to shade in the first place).

                    If you have an unobstructed equator facing location and a single orientation, microinverters will probably increase system cost, but more importantly, they will decrease system reliability - at least in principle and to my engineering training and experience - by increasing system complexity and # of components. So instead of one inverter, you'll have one per panel. More components, more stuff to fail, commonly called the KISS principle

                    Not only that , but all those temperature sensitive electronics are in a hot, nasty environment - a roof - with the added bonus of not being very accessible, particularly if stuck in the middle of a large rectangular array as is often the situation with layouts done with no considerations for access, with a trip to the roof every time one fails. Repeat the next time one fails. From what you describe, a sting inverter equipped system will be as or more fit for purpose from a design standpoint.

                    As for the idea that micros (or optimizers for that matter) allow individual panel monitoring - yup - no doubt about it. They sure do. But as a practical matter, the more common and closer to the reality situation is that as the novelty of PV wears off after a few weeks or so, or less, most folks seem to be inclined to check an array with something like the same frequency they read their electric meter before PV was added - that is, not much, if at all. After a couple of weeks or so the novelty wears off, and the PV system and its production becomes mundane (my guess is that'll be about the same time the monolithic black slab on the roof, fades into/becomes part of the familiar landscape and stops being noticed). The result of all this is that if one panel's output from a bad micro or more wiring (from more system complexity) causes a, say, 5 % drop in output, that may have a higher probability of going unnoticed than if an entire string's or an entire array's output stops. That larger drop will likely get noticed as soon as the next bill arrives.

                    Next question: What importance does cost effectiveness have in your plans ? Many folks would agree with the idea that at some point in time in the future, the long term cost of adding a PV system and it's (probably small) maint. cost plus a residual POCO electric bill electric bill ought to result in a lower (or at least the same, but not higher) long term cost of supplying electricity via the POCO alone.

                    Often, those who delve deeper into the matter and use reasonably realistic assumptions about the future (whatever and however they see that future and the assumptions that go with it) find that the most cost effective, that is, lowest long term cost method of providing electrical service to a residence, is a mix of appropriately sized PV and POCO power. While it may be that a 100 % offset of an electric bill is the most cost effective choice, that's seldom the reality. A 100 % offset may be the choice for reasons other than or in addition to economic or financial, and to be clear, hail the freedom to make choices. I'd only suggest that to design to a 100 % offset is not usually the best choice for those who claim to want PV for economic benefits. I'd only add that a 100% bill offset, while usually not the most cost effective size choice, is still better than > 100% offset, which, by the way the NEM game is currently run at this time and in many/most areas, is about the best way to kill a system's cost effectiveness.

                    One other way to impair cost effectiveness is to add system size and components after the fact as your plans seem to include and as Bob-n remarks about.

                    But, your money, system, design and choices. I'd still respectfully suggest getting and reading the book and consulting other vetted, reliable and knowledgeable sources before you go further, and definitely before you spend any $$. Usually, at least part of someone's analysis paralysis comes from lack of information and knowledge. Get the book and other sources. Your decisions will be better with more information.

                    Take what you want of the above. Scrap the rest.

                    Comment


                    • #11
                      The other thing to think about is whether the 10kW constraint will be in place and for how long. Even a 10% degradation would not affect the outcome as much as a change in the 10kW constraint.
                      9 kW solar, 42kWh LFP storage. EV owner since 2012

                      Comment


                      • #12
                        Originally posted by Ampster View Post
                        The other thing to think about is whether the 10kW constraint will be in place and for how long. Even a 10% degradation would not affect the outcome as much as a change in the 10kW constraint.
                        I'm be interested in finding out from the OP where and how the decision for a 10 kW system size came about. As in, was it "I want a system as large as allowed by the powers that be", or some other method that involved some form of load and economic consideration(s), or other method(s).

                        Comment


                        • #13
                          Originally posted by J.P.M. View Post

                          I'm be interested in finding out from the OP where and how the decision for a 10 kW system size came about. ,,,,,,,,.
                          My interpretation of his original post was that it was an AHJ or power company constraint because he mentioned it in the same sentence as the NEM description. He can clarify if my interpretation is correct. The motivation behind my post was to remind people of that before the thread went down the path of pros and cons of future expansion. I almost made that mistake before I reread his post.
                          Last edited by Ampster; 04-24-2020, 04:46 PM.
                          9 kW solar, 42kWh LFP storage. EV owner since 2012

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                          • #14
                            Hi Ampster, I hope I could add some insights for you.

                            I noticed you are interested in a higher quality solar panel for power performance while opting for Enphase Energy's IQ7+. If your main objective is more power, then I recommend going with the higher panels. They tend to be much more reliable, too. However, if you want to have emergency power during outages I recommend going with the cheaper solar panels and adding the Enphase Ensemble. It's their latest microinverter and it automatically switches from grid-tied to off-grid when it detects a grid outage. It's definitely future-proofing. However, the downside is you will only have power during the daytime as there is no actual storage of energy. It's a drawback, but any power is good power in times of no power.

                            Also, if you wish to do further research and get an outside solar analysis, I recommend contacting a solar permitting and design company. They are selling a product with a set margin while the installers are trying to get the most money per project. So they might be more neutral.

                            I hope this helps! Let me know if you have any questions or need any recommendations for a permitting company to contact.

                            Best,
                            Adam
                            Adam | I have worked in solar since 2014

                            Comment


                            • #15
                              Originally posted by muON View Post
                              If your main objective is more power, then I recommend going with the higher panels.
                              I may have misunderstood the statement that premium panels give you more power.

                              You can get the same power out of any panels. Premium panels may be more efficient (more power per square feet) or more reliable, but they won’t give you more or less power.

                              And if power density is an issue (lack of optimal roof space), you have panels considered as second tier like the REC Alpha that are just as good or better with same level of warranty as “premium” panels. As was mentioned before more important is the longevity of the company, and its warranty replacement policy. Many companies give you a long warranty, but then if a panel needs replacement, they make you jump through hoops and pay for shipping the bad one back, which ends up costing you almost the price of the new panel...

                              Regarding adding a battery this is obviously a different discussion and the Enphase battery is not the only one that could be used.
                              The Enphase battery system is still fairly new, and I have heard installers reporting that so far its reliability was not that great. If so it may take some time before they get that fully on par with other battery solutions.
                              Last edited by scrambler; 04-24-2020, 05:13 PM.

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