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  • #16
    Originally posted by 71SoCal View Post
    Yes, it's really just a math problem. I would definitely appreciate any "real world" data. My location info: zip is 92128, roof tilt is 18.5 deg., azimuth is 240 deg. One panel will shadow partially during the day (north side of fireplace).
    Are there REC incentives? Mass is $0.33/kwh (last quarter)

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    • #17
      Originally posted by NVEnergyLLC View Post
      Are there REC incentives? Mass is $0.33/kwh (last quarter)
      Not for residential in CA at this time. Stay tuned.

      Comment


      • #18
        Originally posted by 71SoCal View Post
        Yes, it's really just a math problem. I would definitely appreciate any "real world" data. My location info: zip is 92128, roof tilt is 18.5 deg., azimuth is 240 deg. One panel will shadow partially during the day (north side of fireplace).
        If you want real world, we're practically neighbors. I have LG260s with M250's. I've never clipped my 250s, but would have if I had 215s. I've seen 242 on my 260's this year. There's one more thing I factored in (guestimated). M250's = 3rd generation. M215's = 2nd generation. Newer technology "may" bring higher reliability. Time will only tell.

        After FTC you are talking less than $350 difference. I have 235 azimuth with minor shading in 92129 at 22 degrees. Are you east or west of I15? my sig is my PVOutput system. If you get a login, and PM me, I'll give you trusted user access for a bit. I have per panel monitoring too on enphase so you can see that too.

        If you stick with Enphase, IMHO I'd pick the newer technology and take advantage of maximum production.

        My 1 cents worth.
        [I][url]http://pvoutput.org/list.jsp?userid=27957[/url][/I]

        Comment


        • #19
          Originally posted by J.P.M. View Post
          To a greater or lesser extent, that depends on the cost of the electricity not produced. If say, 200 kWh/yr. is clipped at $0.20/kWh, 40 bucks/yr. in lost opportunity may or may not be significant to the owner(s). clipping loss will need to be evaluated and a value assigned to it.

          71SoCal: Tilt/azimuth/zip ?
          Just to muddy the waters some more, I'd like to suggest that the inverters working harder and subject
          to clipping might have a higher failure rate. That is inconvenient and costs a lot, esp with labor thrown
          in. That said, I am working on destroying my inverters with clipping, no problemo yet. Bruce Roe

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          • #20
            Originally posted by bcroe View Post
            Just to muddy the waters some more, I'd like to suggest that the inverters working harder and subject
            to clipping might have a higher failure rate. That is inconvenient and costs a lot, esp with labor thrown
            in. That said, I am working on destroying my inverters with clipping, no problemo yet. Bruce Roe
            What helps electronics and reduces failure rates due to "over working" can be related to how well the hardware is cooled. Working hard isn't the problem. NOT getting rid of the damaging heat is.

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            • #21
              While we are making up stories about what might cause a microinverter to fail, I would question why Enphase hasn't released a 275W inverter (or higher), despite the willingness of a customer base to pay for it (even if it won't yield much more energy than the M250 in most installations). Perhaps they've found in testing that even the M250 is at (or slightly beyond) their limit of reliability, and that really the M215 is their most robust design on the market. This would explain why they continue to recommend the M215 for 270 W panels, a recommendation that is counter to Bruce's suggestion that operating at rated output will hurt its life. If the M250 were really more reliable for panels 225 W and above, I would think they would want to limit their warranty exposure and be pushing the M250's in those applications.
              CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

              Comment


              • #22
                Originally posted by sensij View Post
                While we are making up stories about what might cause a microinverter to fail, I would question why Enphase hasn't released a 275W inverter (or higher), despite the willingness of a customer base to pay for it (even if it won't yield much more energy than the M250 in most installations). Perhaps they've found in testing that even the M250 is at (or slightly beyond) their limit of reliability, and that really the M215 is their most robust design on the market. This would explain why they continue to recommend the M215 for 270 W panels, a recommendation that is counter to Bruce's suggestion that operating at rated output will hurt its life. If the M250 were really more reliable for panels 225 W and above, I would think they would want to limit their warranty exposure and be pushing the M250's in those applications.
                Good point.

                I also wonder due to the number of new manufacturers getting in on the microinverter market if Enphase is working on a brand new design but wants to sell off built up inventory of all existing versions.

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                • #23
                  Originally posted by SunEagle View Post
                  Good point.

                  I also wonder due to the number of new manufacturers getting in on the microinverter market if Enphase is working on a brand new design but wants to sell off built up inventory of all existing versions.
                  And perhaps something to do with mgmt.'s view of what's in the co.'s best interests both long/short term, although I'd not place a very high probability on too many American co.'s mgmt. thinking more than about 3 months ahead.

                  Comment


                  • #24
                    Originally posted by sensij View Post
                    While we are making up stories about what might cause a microinverter to fail, I would question why Enphase hasn't released a 275W inverter (or higher), despite the willingness of a customer base to pay for it (even if it won't yield much more energy than the M250 in most installations). Perhaps they've found in testing that even the M250 is at (or slightly beyond) their limit of reliability, and that really the M215 is their most robust design on the market. This would explain why they continue to recommend the M215 for 270 W panels, a recommendation that is counter to Bruce's suggestion that operating at rated output will hurt its life. If the M250 were really more reliable for panels 225 W and above, I would think they would want to limit their warranty exposure and be pushing the M250's in those applications.
                    M215 paired with 270W panel will most certainly be less reliable than M250 + 270W. There're many reasons to have multiple products on the market, even if one is superior -- unit cost, profit margin, replacement cost, BOM, existing tooling and product mix, just to name a few. What costs less to produce also requires less to warranty even at higher rate of failure (remember now they don't cover labor cost for replacement). As you pointed out, I'm too very concerned about Enphase not able to design a higher wattage microinverter after the M250 (released in 2013). While I favor SolarEdge from a technical POV, having competing technologies in the market is always good for consumers. If you believe people who vote with their money know what they're doing, SEDG is now worth almost 4x the capitalization of ENPH (up from 3x just a month ago). I sincerely hope Enphase can come up with something more compelling and quickly. After-all, they practically pioneered the individual tracking concept, very much like RIMM invented the smart phone before AAPL buried them alive.
                    16xLG300N1C+SE6000[url]http://tiny.cc/ojmxyx[/url]

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                    • #25
                      Originally posted by thejq View Post
                      If you believe people who vote with their money know what they're doing.
                      FWIW: People may vote with their money, but that may well say less about their ability to make intelligent choices as informed voters than it does their penchant to usually avoid the longer view if favor of a penny wise, pound foolish and short term, simplistic outlook.

                      Comment


                      • #26
                        Originally posted by sensij View Post
                        For real world data, you might want to review the output of this system on PVOutput.org. There are no 92128 systems in Team San Diego, but the system linked is in 92127 and has LG285's paired with M215's, oriented at 180 deg azimuth with a 22 deg tilt.

                        There will definitely be some clipping... May 10th, for example, shows something like what you might expect to see in springtime. The power output in the middle of the day is capped at 6300 W (28 * 225 W).

                        Now let's look at what PVWatts would have said about that day. If I enable gridded locations and enter the 92127 zip code for that system, along with 180 deg azimuth, 22 deg tilt, premium, roof mount with 6% loss, and lay the model on top of the actual data from around that time (May 11th, to be exact), we see the following:

                        [ATTACH]7061[/ATTACH]

                        PVWatts seems to have expected a little bit more morning cloud cover than what was actually received that day (and/or higher temps than what actually occurred), but matches the system output in the afternoon very well.

                        Now let's use the same method as J.P.M. suggests, and compare the output for the year with and without clipping:

                        PVWatts (no clipping): 14608 kWh
                        Live system: 14429 kWh
                        Difference = 179 kWh

                        If we replicate that model on the system being discussed:

                        7.7 kW (capped at 225*28 = 6300 W)
                        92128
                        240 deg azimuth
                        18.5 deg tilt
                        "premium"
                        roof mount
                        6% loss

                        PWatts (no clipping) = 13771 kWh
                        Projected (with clipping) = 13724 kWh
                        Difference = 47 kWH

                        At 0.20 / kWh, that is worth about $9.40 / annually.

                        If you want to use TOU pricing with $0.49 / kWh from 12 pm to 6 pm, it is more like $23 annually.

                        I just don't see the financial justification for spending $500 for what is certainly worth less than $50 annually in cost avoided. However, as I think some forum members have shown, there is an emotional component to the decision for many people. "Loss Aversion" is influential in decision making, and many people look at the flat top of a clipped day and freak out, even when accepting that clipping was the better financial decision. For those people, spending the extra $500 might be worth the peace of mind, even if some of us only see money spent for no tangible return.
                        Thanks for the great run through. It really puts a point on it.
                        Funny how you can still be drawn to doing the 250's emotionally even when you see the math.

                        Comment


                        • #27
                          Originally posted by Alisobob View Post
                          [ATTACH=CONFIG]7059[/ATTACH]

                          I clip a little with 270 watt Solar World panels, hooked to M215's.

                          M250's were a little pricier when I did my install, and I was told I would never recoup the price difference....

                          Now? I may have gone with them.

                          Its a tough call....
                          Looks like you barely clipped the nipple. I say this graph proves the 215 works amazingly well for you.

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                          • #28
                            Originally posted by nomadh View Post
                            I say this graph proves the 215 works amazingly well for you.
                            I'm getting 42 + Kwh's per day off of my 6.4 KW system.

                            Thats slightly more than 6.6 KwH's output, per nameplate KW.

                            I'm clipping, but it cant amount to much I guess.....

                            As least that's what everyone tells me....

                            Comment


                            • #29
                              Originally posted by nomadh View Post
                              Thanks for the great run through. It really puts a point on it.
                              Funny how you can still be drawn to doing the 250's emotionally even when you see the math.
                              Lots of things in life dont add up mathmatically. If you're married, it probably doesnt pencil out 50 percent of the time.

                              Its really more from a "i've done everything I can to feel like "I" made the right decision".

                              1. The difference for the OP is really less than $15/unit before FTC. After, its $10/unit
                              2. Its newer technology. Perhaps better reliabilty, and new features that can be added, where the old technology wont support it.
                              3. you will get some return on the additional cost. How much will never really be known.
                              4. bragging rights, and having latest and greatest
                              5. piece of mind. you will not fret over what you might be missing out on if you'd have gone with the bigger units.

                              I know there are more.

                              These are all intangible reasons. There are many other "intangible" reasons we justify purchases throughout our lifetime.

                              Insurance, warranties, latest and greatest, peace of mind, perceived resale value, perceived reliability, etc....

                              If everyone evaluated all purchases based strictly on math and 3 year ROI, you'd still be buying 5 year old iphone 4's, LCD TV's, and ignore extended warranties (cell phones, TV's, autos, etc..) to name a few. The intangibles add up to peace of mind. I sleep very well knowing my cars are covered for 125k miles for 8 years for practically any failure other than brakes, tires, and oil changes. I know I've used every extended warranty I've ever purchased to more than 3 times what I paid for it.

                              Should I buy the 2015 model or the 2016 model. Great deal on the 2015, but damn, that new model 2016 looks pretty cool.

                              Its emotional, and its therapuetic. Not having to worry about, "did I make the right decsion by going the cheaper route"? Should I have gone with the bigger, better, faster, newer?

                              If we were talking $1500 bucks, I'd say hell no. But $300 on a 15-25k purchase Thats in the noise for the vast majority.

                              Dont get me wrong, I pride my self on being frugal, and getting the best deal whenever possible. But thats usually on commodity items that I have experience with and know what the risks are. When you are dealing with a purchase that you have no experience with, and are taking advice from strangers; thats where you take everyone's inputs and make your own decsion. Great personal fortitude for saying I've done the math and I trust everyone elses, and I dont think it pencils out for me to spend a few hundred bucks. For me, the price is so small, and the peace of mind so great, i dont even think about it.
                              [I][url]http://pvoutput.org/list.jsp?userid=27957[/url][/I]

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                              • #30
                                I won't question most of your logic: hey, if it makes you feel good why not. But the suggestion that the M250 is in some way "newer technology" is incorrect. Enphase updated the M215 last year to same 4th generation platform as the M250. I suspect the most significant internal difference between the units is the size of the capacitors. And for what's it's worth, the capacitors are the biggest reliability issue and my guess would be the failure rate is higher on the larger ones.

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