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  • #31
    Originally posted by perch View Post
    Thanks for the advice.

    Yes we have different shading throughout the day and also different roof spaces. The west roof area is far smaller than the north. The shading comes from tall trees to the North East to East and then trees in the West in the afternoon (but the west ones I can prune to stop their shading).

    And sorry for my ignorance but why micro's over optimizers?
    You really don't need micro-inverters. Shading is a big problem with the value of solar entirely. How bad is it? enough to cover a few modules for many hours? One hour?

    I suppose shading is primarily a problem with low sun in the winter but not in the summer?

    I want to show you how to use multi-MPPT string inverters for a similar benefit. If you have two arrays you can get two smaller inverters. I use PowerOne Aurora inverters. Each has two MPPT controllers within each. I have 32 modules making up two arrays (both facing South in the northern hemisphere). In your case, your two arrays could be mounted on separate roof angles, using two 3.6 inverters, you could endure shading if wiring was done such that the lower modules and upper modules in each array plugged into each separate MPPT controller in each inverter. The price would be roughly the same or lower than micro-inverters.

    Once you have shading over a small part of all the lower level modules, neither micro-inverter nor string inverter is going to win-out. The group of cells will just produce a lowly amount. You might get a few more Wh a day with micro-inverters as the early part of the shading comes in. But that is pennies per day.

    Micro-inverters do not really "draw in the sun" when shaded. they produce very little of course when the module is obscured by shade from trees.

    Talk to a local installer who can show the variations between installation methods. A 290W or 300W module can perhaps fully produce using a string inverter during peak sun but would be clipped at 250W with some of the micro-inverters. Except for the PowerOne 300W micro-inverter.

    My system is much like this:

    XXXXXXXX - - inverter 1 mppt 1 \ .
    YYYYYYYY - - inverter 1 mppt 2 / \ ....... LINE OUT
    XXXXXXXX - - inverter 2 mppt 1 \ ./
    YYYYYYYY - - inverter 2 mppt 2 /

    If Module set Y on either inverter is shaded, the X line of modules is producing fully and the minor output from Y is still collected. Unlike a single inverter with one large input and merged strings.
    PowerOne 3.6 x 2, 32 SolarWorld 255W mono

    Comment


    • #32
      I've been browsing this forum over the past couple of weeks researching as much as I can for the best PV system for my needs. I've come across this thread in hopes of really identifying if microinverters are better than optimizers or vice versa.

      Our home has some potential shade areas and so it's in my best interest not to go with a central inverter. I really haven't found any clear benefit for either system (each company has reports that their respective solutions are better/more efficient) which sort of makes it a wash.

      I guess my own conclusion is that both systems are good for managing homes with partial shade issues, have a 25 year warranty, and should basically work well in CA. I would guess the main decision would simply be if your installer has experience with said system and the overall price?

      Comment


      • #33
        Originally posted by jcl2k6 View Post
        I guess my own conclusion is that both systems are good for managing homes with partial shade issues, have a 25 year warranty, and should basically work well in CA. I would guess the main decision would simply be if your installer has experience with said system and the overall price?
        Did you arrive at this conclusion knowing that Enphase has stopped including labor in their warranty while SolarEdge still include labor in their warranty? With a potential for a high number of multi-point failures up on the roof that may need frequent access to the roof to repair, the labor cost to go up the roof multiple times is going to be a much bigger repair cost than the part cost.

        Also, the less electronics you have on your rooftop baking day-in-day-out in the summer, the less potential for failure. The Enphase approach has the whole enchilada up on the roof, both optimizer circuitry and inverter circuitry. On the other hand, the SolarEdge approach only has optimizers up on the roof, while the inverter components are on the cooler ground.

        I own string inverters on the ground so I'm not partial to SolarEdge or anything. It's just common logic the way I see it.

        Comment


        • #34
          Originally posted by jcl2k6 View Post
          if microinverters are better than optimizers or vice versa.
          Due to the shade you have identified that you have a problem - OK

          Both types work but only a couple of companies have any real track record - I would stick with them for sure. Enphase and Tigo are two that come to mind.
          [SIGPIC][/SIGPIC]

          Comment


          • #35
            Originally posted by Volusiano View Post
            Did you arrive at this conclusion knowing that Enphase has stopped including labor in their warranty while SolarEdge still include labor in their warranty? With a potential for a high number of multi-point failures up on the roof that may need frequent access to the roof to repair, the labor cost to go up the roof multiple times is going to be a much bigger repair cost than the part cost.

            Also, the less electronics you have on your rooftop baking day-in-day-out in the summer, the less potential for failure. The Enphase approach has the whole enchilada up on the roof, both optimizer circuitry and inverter circuitry. On the other hand, the SolarEdge approach only has optimizers up on the roof, while the inverter components are on the cooler ground.

            Thanks for your response Volusiano. Yeah, I read about Enphase potential for multi-point failures, but it didn't seem like any epidemic. Also regarding the warranty not covering labor, I haven't been able to find that actual phrase on their warranty print-out. Though if it's indeed NOT covered, it would be a "win" for the Solaredge column. Fortunately, it appears replacing the Enphase micro-inverter is relatively straight-forward in the event of a failure.

            I agree that the SolarEdge approach seems to be a better design and probably will get my vote if we decide to pull the trigger before yet another wave of technology advancement shows up.

            Comment


            • #36
              Originally posted by russ View Post
              Both types work but only a couple of companies have any real track record - I would stick with them for sure. Enphase and Tigo are two that come to mind.
              Thanks russ! After reading this I had to go researching Tigo vs. SolarEdge. It appears that even though they are considered "optimizers" they are very different in their approach: http://matter2energy.wordpress.com/2...-vs-solaredge/

              Very interesting read if you can absorb all the info (I couldn't on the first pass ).

              Great information and thanks for helping out!

              Comment


              • #37
                Originally posted by jcl2k6 View Post
                Thanks for your response Volusiano. Yeah, I read about Enphase potential for multi-point failures, but it didn't seem like any epidemic. Also regarding the warranty not covering labor, I haven't been able to find that actual phrase on their warranty print-out. Though if it's indeed NOT covered, it would be a "win" for the Solaredge column. Fortunately, it appears replacing the Enphase micro-inverter is relatively straight-forward in the event of a failure.

                I agree that the SolarEdge approach seems to be a better design and probably will get my vote if we decide to pull the trigger before yet another wave of technology advancement shows up.
                I'll address the 3 points you made which I highlighted in bold above.

                I'm not sure why the no-labor clause is so hard for you to find, unless you don't want to really look for it. It took me just a few seconds to google up their warranty and find it right away. And I wasn't even trying to look hard. Here's the link to the M250 Warranty that I googled. Below is the excerpt on the no-labor-included clause, found in the 4th paragraph of the warranty.

                The Limited Warranty covers a replacement unit to replace the Defective Product, but does not include labor costs related to (1) un-installing the Defective Product or (2) if applicable, re-installing a repaired or replacement product.

                The Enphase multi-point failures doesn't seem epidemic (yet) because microinverters are relatively new to the game. They haven't been around that long to be able to prove their reliability and/or liability yet. Most likely, failure won't happen for at least several years into the warranty. String inverters on the ground has had a long enough history to show their reliability. And they seem to last longer than 10 years but between 10-15 years or so, they start to fail. So assuming that microinverters have the same lifetime as string inverters, let's say 15 years, even though they get baked on the hot roof top year in and year out while string inverters don't. So after 15 years, one microinverters start to fail after another, you will only then see the "epidemy", as you put it. But by then it's too late. Then you'll have to start paying for labor to retrieve and replace one microinverter after another, multiple trips to and from the roof on each point of failure. By then, you'll appreciate how important the labor warranty will be.

                Replacing a string inverter is straight forward. You stay on the ground, replace it one time and you're good to go for another 15 years. But replacing a microinverter is not as straightforward as you think. You have to climb up on the roof. If the arrays are all bunched up and the failed part is on the panel smack in the middle of the array, you'll have to remove all the neighboring panels in order to get to the middle panel. Sure it's easy to take the microinverter out, but now you have to put all the neighboring panels back, get off the roof and send the failed microinverter in to Enphase for inspection. When you get the replacement, the whole process must be repeated again, on the roof, removing neighboring panels, replace microinverter, put all panels back again.

                So tell me if you still think the whole process is straightforward. And oops, two months later, another microinverter fails. A few months later, yet another one fails. If you have 2 dozens microinverters, you'll have to pay for labor 24x2 trips up and down the roof because labor is not covered under warranty. Now tell me if any of it is still straightforward for you anymore. Especially when you're the one who's left holding the bag paying for all the labor for all those trips up and down the roof.

                Obviously Enphase has figured out the liability of the multiple point failures and revised their warranty to remove the labor warranty. Shouldn't that be a big enough sign to unsuspecting buyers to heed?

                Comment


                • #38
                  Would it not be a prudent idea if you have Enphase Microverters to by a spare

                  If you own your system and do not have a labor warranty. It would seem to me that after the first failure it would be cheaper to just purchase a spare much like a spare tire on a car. This would at least eliminate a second labor charge to replace a bad one. I think they only cost about $250 each new and one might even be able to get a used or repaired one cheaper.

                  Comment


                  • #39
                    Originally posted by wanabefree View Post
                    If you own your system and do not have a labor warranty. It would seem to me that after the first failure it would be cheaper to just purchase a spare much like a spare tire on a car. This would at least eliminate a second labor charge to replace a bad one. I think they only cost about $250 each new and one might even be able to get a used or repaired one cheaper.
                    This is an excellent idea, at least to cut the labor cost per failure from 2 trips (1 to retrieve and 1 to replace) down to 1 (retrieve and replace using the spare at a same time). Then you keep the replacement one sent by the manufacturer as a spare for the next failure.

                    Comment


                    • #40
                      Originally posted by wanabefree View Post
                      If you own your system and do not have a labor warranty. It would seem to me that after the first failure it would be cheaper to just purchase a spare much like a spare tire on a car. This would at least eliminate a second labor charge to replace a bad one. I think they only cost about $250 each new and one might even be able to get a used or repaired one cheaper.
                      How do you eliminate labor by having a spare? You probably save the time from getting replacement

                      Comment


                      • #41
                        Originally posted by silversaver View Post
                        How do you eliminate labor by having a spare? You probably save the time from getting replacement
                        You reduce the number of trips per failure down from 2 to 1. Instead of 1 trip to remove the bad part and 1 trip later to install the replacement part, now it's just a single trip to remove/replace at the same time. You don't eliminate the labor entirely. You just reduce it by half.

                        Comment


                        • #42
                          Originally posted by Volusiano View Post
                          You reduce the number of trips per failure down from 2 to 1. Instead of 1 trip to remove the bad part and 1 trip later to install the replacement part, now it's just a single trip to remove/replace at the same time. You don't eliminate the labor entirely. You just reduce it by half.
                          I got it now. That is a good idea. The only bad is you will not know if replacement inverter were good or bad once receive.

                          Comment


                          • #43
                            Originally posted by Volusiano View Post
                            I'll address the 3 points you made which I highlighted in bold above.

                            I'm not sure why the no-labor clause is so hard for you to find, unless you don't want to really look for it. It took me just a few seconds to google up their warranty and find it right away. And I wasn't even trying to look hard. Here's the link to the M250 Warranty that I googled. Below is the excerpt on the no-labor-included clause, found in the 4th paragraph of the warranty.

                            The Limited Warranty covers a replacement unit to replace the Defective Product, but does not include labor costs related to (1) un-installing the Defective Product or (2) if applicable, re-installing a repaired or replacement product.

                            The Enphase multi-point failures doesn't seem epidemic (yet) because microinverters are relatively new to the game. They haven't been around that long to be able to prove their reliability and/or liability yet. Most likely, failure won't happen for at least several years into the warranty. String inverters on the ground has had a long enough history to show their reliability. And they seem to last longer than 10 years but between 10-15 years or so, they start to fail. So assuming that microinverters have the same lifetime as string inverters, let's say 15 years, even though they get baked on the hot roof top year in and year out while string inverters don't. So after 15 years, one microinverters start to fail after another, you will only then see the "epidemy", as you put it. But by then it's too late. Then you'll have to start paying for labor to retrieve and replace one microinverter after another, multiple trips to and from the roof on each point of failure. By then, you'll appreciate how important the labor warranty will be.

                            Replacing a string inverter is straight forward. You stay on the ground, replace it one time and you're good to go for another 15 years. But replacing a microinverter is not as straightforward as you think. You have to climb up on the roof. If the arrays are all bunched up and the failed part is on the panel smack in the middle of the array, you'll have to remove all the neighboring panels in order to get to the middle panel. Sure it's easy to take the microinverter out, but now you have to put all the neighboring panels back, get off the roof and send the failed microinverter in to Enphase for inspection. When you get the replacement, the whole process must be repeated again, on the roof, removing neighboring panels, replace microinverter, put all panels back again.

                            So tell me if you still think the whole process is straightforward. And oops, two months later, another microinverter fails. A few months later, yet another one fails. If you have 2 dozens microinverters, you'll have to pay for labor 24x2 trips up and down the roof because labor is not covered under warranty. Now tell me if any of it is still straightforward for you anymore. Especially when you're the one who's left holding the bag paying for all the labor for all those trips up and down the roof.

                            Obviously Enphase has figured out the liability of the multiple point failures and revised their warranty to remove the labor warranty. Shouldn't that be a big enough sign to unsuspecting buyers to heed?
                            Whoa ... it appears you may have a beef with Enphase or something. I'm not trying to convince anyone that they make a good/bad product. There certainly are a lot of opinions out there. I appreciate you pointing out the warranty details and as I stated in my prior post, if they in fact do not cover labor in their warranty then (no pun intended) the edge goes to SolarEdge.

                            My neighbor got his PV system installed last year and is really impressed with his Enphase MIs. I'm still trying to digest information as I read and research ...

                            Comment


                            • #44
                              Originally posted by jcl2k6 View Post
                              Whoa ... it appears you may have a beef with Enphase or something. I'm not trying to convince anyone that they make a good/bad product. There certainly are a lot of opinions out there. I appreciate you pointing out the warranty details and as I stated in my prior post, if they in fact do not cover labor in their warranty then (no pun intended) the edge goes to SolarEdge.

                              My neighbor got his PV system installed last year and is really impressed with his Enphase MIs. I'm still trying to digest information as I read and research ...
                              I actually never had any dealing with Enphase before so I don't really have any beef with them. I just saw your comments about how straightforward you think the microinverter replacement process is and how you don't see any epidemic failure yet, so I just wanted to point out the fallacies of that line of thinking, that's all.

                              And I never said that Enphase make bad products. I just criticize the approach of having multi-points of failure. Sure, there are good reasons to have localized optimization, like to deal with shading issues. I can buy into the idea of having localized optimizers up on the roof to deal with shading. But having the inverter circuitry up on the roof as well is not a good idea in my opinion. If the manufacturer thinks that it's not a problem, then the manufacturer should put the money where their mouth is and provide both parts AND labor warranty for their products.

                              Comment


                              • #45
                                Solar rule 101: no shade, no micro inverters. Less failure means less trouble. You are getting an appliance to generate power, not like a smartphone.

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