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  • It has been beaten to death but...

    I have 2 quotes for 6kw (little less for the sunpower)
    $3.40/watt for Panasonic panels (string inverter)
    $3.55/watt for x22 Sunpower with built in MI.

    Assuming house in California no shading issues. Does this finally qualify the sunpower haters to say yes to the best? Or should I go with Panasonic?

  • #2
    Originally posted by Collaborator View Post
    I have 2 quotes for 6kw (little less for the sunpower)
    $3.40/watt for Panasonic panels (string inverter)
    $3.55/watt for x22 Sunpower with built in MI.

    Assuming house in California no shading issues. Does this finally qualify the sunpower haters to say yes to the best? Or should I go with Panasonic?
    with no shading issues I'd go with string inverter for less maintenance in the long run. 'Best' is subjective term and IMO in this case SP is far from it but it's your money.

    Comment


    • #3
      What is a string inverter ? Sounds useful
      600W, 40A MPPT, 230AH FLA,24V Samlex 1500W

      Comment


      • #4
        Originally posted by Gdwats View Post
        What is a string inverter ? Sounds useful
        Lots (10-16) of panels wired in series strings and fed back to the inverter. This results in a high DC voltage (generally about 250 to 500 volts) which means wire cost is less, since higher voltage=less current and less copper needed.

        If more strings are needed, they are added separately, and either wired in parallel or fed into separate channels in the string inverter. Generally you will have one, or sometimes two, string inverters for a home installation.

        Benefits of string inverters include inverter being in a relatively protected/accessible place (inside garage, on outside wall near utility entrance) and having no electronics on the roof. Drawbacks include not being very tolerant of partial shading and the inability to monitor individual panels.

        Big competition to this are microinverters, which uses one inverter per panel (or per 2-4 panels) with inverters located on the roof. 240VAC is run to each inverter.

        Note that Solaredge does both - they have individual optimizers on the roof AND a string inverter located somewhere convenient, Some think that's the best of both worlds; some think it's the worst - but it's an intermediate option that shares characteristics of both.

        Comment


        • #5
          Originally posted by max2k View Post

          with no shading issues I'd go with string inverter for less maintenance in the long run. 'Best' is subjective term and IMO in this case SP is far from it but it's your money.
          well the best on paper anyway... best warranty, best material (copper versus aluminum), most physically durable. As for there other claims, well those could very well be subjective and bull. I can't speak to those things since there are too many variables to prove. Assuming they are still around, they are the best... on paper. I have not fully decided, but I'm leaning towards them since the price is close "ish".

          It seams that everyone comments here, are don't buy sunpower because it's overpriced. Is this quote overpriced? Also as far as micro inverters, they all offer 25 year warranty and string inverters are only good for 10 years. Why would a corporation offer a superior warranty on an inferior technology? Do you have failure statistics to back up your "less maintenance claim"? I would like to know before purchasing since this would be important information. I was thinking a single point of (more) likely failure vs 20 individual points of (less) failure would be far far less downtime over the long run. Since all the failure data I have seen indicates almost a assured failure of a string inverter after 10 years, which also assures a 3k bill every 10 years.

          Being in the risk aversion business makes me lean towards the warranty of sunpower, but it is in conflict with my worries about there future.

          Comment


          • #6
            Originally posted by Collaborator View Post

            It seams that everyone comments here, are don't buy sunpower because it's overpriced. Is this quote overpriced?
            You might be able to find $3.00 / W for a basic installation with more generic (but still acceptable quality) panels, if you keep shopping around. Difficult roof geometry or materials, long wire runs, service panel upgrades, etc will add to that.
            CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

            Comment


            • #7
              Originally posted by Collaborator View Post

              well the best on paper anyway... best warranty, best material (copper versus aluminum), most physically durable. As for there other claims, well those could very well be subjective and bull. I can't speak to those things since there are too many variables to prove. Assuming they are still around, they are the best... on paper. I have not fully decided, but I'm leaning towards them since the price is close "ish".

              It seams that everyone comments here, are don't buy sunpower because it's overpriced. Is this quote overpriced? Also as far as micro inverters, they all offer 25 year warranty and string inverters are only good for 10 years. Why would a corporation offer a superior warranty on an inferior technology? Do you have failure statistics to back up your "less maintenance claim"? I would like to know before purchasing since this would be important information. I was thinking a single point of (more) likely failure vs 20 individual points of (less) failure would be far far less downtime over the long run. Since all the failure data I have seen indicates almost a assured failure of a string inverter after 10 years, which also assures a 3k bill every 10 years.

              Being in the risk aversion business makes me lean towards the warranty of sunpower, but it is in conflict with my worries about there future.
              not sure where did you get aluminum vs copper argument. Most likely panels themselves as I can't imagine someone runs aluminum wires for the system. The SP panels while great product don't justify higher price tag unless you have really special circumstances where their higher efficiency could be beneficial. Otherwise all major brands nowadays already figured out how to produce reliable panels so there's no reason to overpay for SP product.

              is labor for SP micro replacement part of the warranty? I doubt but worth checking because that would be your bill in the future and anyone going up the roof charging top dollars. For my own system which I ended up installing myself I obviously could go there but since I'm lazy I still went with string inverter based system.

              I don't have SP micro failure stats. FWIW there was recent thread around here discussing reliability of Enphase microinverters and the headache they gave to the system owner. I realize this is different company but still makes for educational read.
              Last edited by max2k; 09-01-2017, 05:59 PM.

              Comment


              • #8
                Man you really do sound like a Collaborator. You havent included any details which sounds suspicious.

                Major SP vendor in my area gave me a quote for panels, then gave me an alternate quote for some no name brand panels I hadnt heard of for a discount.
                Sunpower at 4/watt,
                No name at $3.80.
                House in California.

                Did my quote "qualify to the Sunpower haters to say yes to the best?" Your argument is specious.

                I went with another vendor and Canadian Solar at 2.98/watt.

                You do not have to convince us. It is your money.
                Last edited by cebury; 09-01-2017, 06:14 PM.

                Comment


                • #9
                  Originally posted by Collaborator View Post
                  well the best on paper anyway... best warranty, best material (copper versus aluminum)
                  Pretty much no one uses aluminum wire on home (panels on roof, inverter in garage) systems, nor is the selection of panels/inverters tied to such a decision.
                  It seams that everyone comments here, are don't buy sunpower because it's overpriced. Is this quote overpriced? Also as far as micro inverters, they all offer 25 year warranty and string inverters are only good for 10 years.
                  Where do you get that? There are microinverters that have 10 year warranties; you can get SolarEdge string inverters with 25 year warranties.

                  Buy Sunpower if you like, or buy something else. But make the decision based on real information.

                  Comment


                  • #10
                    Originally posted by cebury View Post
                    Man you really do sound like a Collaborator. You havent included any details which sounds suspicious.

                    Major SP vendor in my area gave me a quote for panels, then gave me an alternate quote for some no name brand panels I hadnt heard of for a discount.
                    Sunpower at 4/watt,
                    No name at $3.80.

                    Were my choices. I went with another vendor.

                    Canadian Solar 2.98/watt.

                    was a house in California

                    Does this prove to the Sunpower haters once and for all to say Yes to the best? You argument is specious.
                    Semper Solaris is where I got the sunpower quote. The Panasonic quote was solar city.

                    Good price for your Canadian solar panels, not for my consideration with my roof space.

                    Comment


                    • #11
                      If you already are very fond of Sunpower and their sales pitch arguments, you will very likely be satisfied with your purchase. They are good stuff. If you have the money, they are the name brand, just a wee bit better for perrformance, IMO very questionable if they will survive long enough to honor any long term warranty, but you are paying for that label and marketing. I dont recall any regular here saying they hate Sunpower. They are trying to save folks money. I would strongly suggest you get more vendor quotes. Or dont, just buy Sunpower, be happy and dont look back. Depends all on you and your circumstances.

                      Comment


                      • #12
                        Originally posted by jflorey2 View Post
                        Pretty much no one uses aluminum wire on home (panels on roof, inverter in garage) systems, nor is the selection of panels/inverters tied to such a decision.

                        Where do you get that? There are microinverters that have 10 year warranties; you can get SolarEdge string inverters with 25 year warranties.

                        Buy Sunpower if you like, or buy something else. But make the decision based on real information.
                        real information .. like material science? The material the solar panel is made with. Copper in the SP panel can expand and contract a lot more then the aluminum CVD in the Panasonic panel, wether or not that translates into a longer life, I'm not sure, independent test seem to think so. Are you paid say biased information with open ended arguments?

                        To to be fair I knew coming to this forum would result in these type responses. Which I suppose helps me solidify my choice. If certain individuals points are very biased then I go the opposite.


                        Comment


                        • #13
                          If you go with Sunpower, please consider requesting a monitoring system that will allow you to join PVOutput.org and share your data. No better way to prove the doubters wrong than to put your production numbers up against those of your neighbors and see how they hold up over time. If you are in San Diego (you mentioned Semper Solaris), Team San Diego is the place to be.

                          [you may find that Sunpower's monitoring system is especially resistant to sharing data, and 3rd party monitor would be required. I try not to read into that too much, but can say that my two Canadian Solar systems appear to perform as well anyone's for the location and orientation]
                          CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

                          Comment


                          • #14
                            Originally posted by Collaborator View Post
                            real information .. like material science?
                            Like the warranty lengths of microinverters vs string inverters.
                            To to be fair I knew coming to this forum would result in these type responses. Which I suppose helps me solidify my choice. If certain individuals points are very biased then I go the opposite.
                            I am curious as to what you think my bias is. It would be interesting to hear.

                            Comment


                            • #15
                              Originally posted by Collaborator View Post
                              real information .. like material science? The material the solar panel is made with. Copper in the SP panel can expand and contract a lot more then the aluminum CVD in the Panasonic panel, wether or not that translates into a longer life, I'm not sure, independent test seem to think so.
                              What I see in Sunpower's marketing materials is their claims of larger metal on the back (so more resistant to corrosion) and talk about how their cell-to-cell interconnect is designed with strain relief. And that if there isn't strain relief you are likely to have reliability issues due to the numerous thermal cycles.
                              I would agree that the larger metal is inherently more resistant to corrosion. But if the seal is broken and stuff corrodes, what's happening to the cells? I'd be just as concerned about them as the interconnect. And I haven't heard large amounts of concern about corrosion in commercially produced panels.
                              For the strain relief - even their marketting material says that there are other methods of doing strain relief. SP claims their method is good (and it looks good to me). They don't really say others aren't good, only that it's possible to do a bad design and not have strain relief. IMO any of the name-brand manufacturers are going to have sufficient strain relief. Maybe it'll last through 30 years of thermal cycles and SP will last through 50 years - maybe they'll both last 50 years. I don't think there's enough information to reach a real conclusion.

                              I did not see anything about the copper itself expanding and contracting more than aluminium CVD in panasonic panel.
                              And I wouldn't be worried about Aluminum CVD expansion/contraction. CVD = Chemical Vapor Deposition. Aluminum CVD would be the small metal lines that were created on the wafers as they were created. The only concern with that is the expansion/contraction of the silicon cell compared to the metal. And Aluminum and Copper thermal expansion coefficients are fairly similar compared to silicon's. So it's unlikely you'll have issues there with aluminum that would not also affect copper.

                              Semper Solaris is where I got the sunpower quote. The Panasonic quote was solar city.
                              Both of those are higher cost vendors I think.
                              Look around a little more and you can get under $3 most likely.
                              And probably installed by a team that has worked as subcontractor to those guys.
                              If you're in San Jose / Santa Cruz area, I'd have a recommendation for a company based in Santa Cruz - not sure if they work outside that area.

                              BTW solar edge is on the roof with multiple failure points just like MI.
                              Micro-inverters are more complex than optimizers.
                              My understanding is that (among other things) they have capacitors inside them.
                              When I bought my system I chose to go with optimizers (Solaredge). My reasoning is that it has a better track record than microinverters. I was concerned about the electrical components in the microniverters being more complex and more susceptible to problems due to heat than the optimizers.


                              Does this finally qualify the sunpower haters to say yes to the best?
                              Put another way:
                              Is a >15% premium ($3.55 vs. $3.00) worth it for the sunpower brand name and possibly 1-2% higher output over lifetime of system.
                              IMO no. At least not usually
                              But if you like the brand name, or are very space constrained it can be a good choice.
                              obviously you're not space constrained - since the sunpower system is fewer watts than the Panasonic system.

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