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DIY grid-tie Solar install - West facing roof vs south facing ground mount

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  • #16
    Originally posted by bcroe View Post

    Right, strings avoid additional AC voltage at the inverter. Bruce Roe

    Ah... I think I misread your post. More grief with micros... gotcha

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    • #17
      If you go ground mount, microinverters are a complete waste. Especially if you're saying no shade. You will have higher loss as was mentioned.

      I'm definitely a fan of ground mount setups. However it is significantly more money. That being said it adds into the ROI time. It's also alot more work. Alot more work. I didn't have much of a choice on my property. But I definitely think the pros outweigh the cons.

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      • #18
        Originally posted by Markyrocks69 View Post
        I'm definitely a fan of ground mount setups. However it is significantly more money.
        NEC 2017 has evened that up a bit

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        • #19
          Originally posted by nwdiver View Post

          I'm really perplexed on the popularity of Enphase. What makes it worse is that when I ask people why they prefer Enphase I've never been given a reason that's accurate. Lower Line Losses? No. More Shade Tolerant? Not really. The most popular reason is that if one panel is shaded in a string of 14 panels that the other 13 panels have their output reduced with a string inverter... which is 100% false.
          Shade tolerance was one reason I went with Enphase, since I have trees and a chimney that pass over various panels during the day and I didn't want one or two shaded panels taking down a series string. I don't see any other advantage other than rapid shutdown and panel level monitoring which I really don't need. I don't want a string inverter with optimizers for various reasons, so Enphase seemed like a good idea.

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          • #20
            From a DIY perspective, I'd add that micros are significantly easier to install as well.

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            • #21
              Originally posted by Spektre View Post
              From a DIY perspective, I'd add that micros are significantly easier to install as well.
              In which way?

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              • #22
                Originally posted by Spektre View Post
                From a DIY perspective, I'd add that micros are significantly easier to install as well.
                For an extensive system, the wiring for the micros will probably be much more difficult. Bruce Roe

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                • #23
                  I have decided to use an SMA string inverter for my system.

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                  • #24
                    Originally posted by Coach v View Post
                    I have decided to use an SMA string inverter for my system.
                    IMO, you will have a cleaner, simpler system that will have a higher probability of fewer problems. KISS.

                    Good luck.

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                    • #25
                      Originally posted by Markyrocks69 View Post
                      In which way?
                      Plug and play connections (mostly)
                      No messing with energized dc cables
                      No additional rapid shutdown device needed
                      Ease of replacement if necessary
                      For my installation, string inverters would need to be in my garage, so additional 50-60' run to/from exterior mounted panel

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                      • #26
                        Originally posted by Spektre View Post

                        Plug and play connections (mostly)
                        No messing with energized dc cables
                        No additional rapid shutdown device needed
                        Ease of replacement if necessary
                        For my installation, string inverters would need to be in my garage, so additional 50-60' run to/from exterior mounted panel
                        Mc4 connections aren't plug and play? If your messing with energized DC lines your doing something wrong. Ease of replacement. Lol youd probably never even know if you had 3 or 4 dead mico inverters. Why does your string inverter need to be in the garage? Most people just bolt it to the side of their house. I will say buying whatever special cable is required for enphase is significantly more expensive than 10 gauge Pv wire. Mc4 connectors are dirt cheap. But you're right if the microinverter needs replacing in a roof mount situation it's much easier to climb up there, Remove the panel(s) replace and reinstall than to replace a string inverter that's on the ground and exposed.

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                        • #27
                          Originally posted by markyrocks69 View Post

                          mc4 connections aren't plug and play? If your messing with energized dc lines your doing something wrong. Ease of replacement. Lol youd probably never even know if you had 3 or 4 dead mico inverters. Why does your string inverter need to be in the garage? Most people just bolt it to the side of their house. I will say buying whatever special cable is required for enphase is significantly more expensive than 10 gauge pv wire. Mc4 connectors are dirt cheap. But you're right if the microinverter needs replacing in a roof mount situation it's much easier to climb up there, remove the panel(s) replace and reinstall than to replace a string inverter that's on the ground and exposed.
                          fwiw, +1.

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                          • #28
                            Originally posted by Markyrocks69 View Post

                            Mc4 connections aren't plug and play? If your messing with energized DC lines your doing something wrong. Ease of replacement. Lol youd probably never even know if you had 3 or 4 dead mico inverters. Why does your string inverter need to be in the garage? Most people just bolt it to the side of their house. I will say buying whatever special cable is required for enphase is significantly more expensive than 10 gauge Pv wire. Mc4 connectors are dirt cheap. But you're right if the microinverter needs replacing in a roof mount situation it's much easier to climb up there, Remove the panel(s) replace and reinstall than to replace a string inverter that's on the ground and exposed.
                            We all know how JPM feels about micros, so I'm not surprised he chimed in. Marky, based upon your adventures getting your system up and running, I'm surprised you're so anti-micro.

                            Enphase's Enlighten software lets you know exactly which micro is misbehaving. Replacing one on my flat roof with tilted panels would take me about 15 mins.
                            You are aware that your panels are putting DC onto the line as soon as you connect them, right? There is no AC output from your micro until you tell it to.
                            It's hot here in Phoenix, so putting string inverters in direct sunlight is not the greatest of ideas.
                            There's nothing special about Enphase trunk cable - it's only ~$1/ft, and you only need to run it from the end of your string to your combiner box/panel.

                            Anyways, to each his own. As a DIY person, micros for me are way easier.

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                            • #29
                              The strings are not quite the No Brain level. On a string of 12 panels I bring together but
                              do not join panels 4-5, and 8-9. This leaves the system in much lower voltage sections,
                              with no possible current flow if done correctly. Once all is ready, I join the last 2 pairs of
                              MC4s and make tests. I connect this tool to each string pair, to observe voltage with some
                              current capability. I connect between ground and to one string end, then the other end
                              and should observe no power if there are no ground faults. Later my DC Clamp On
                              ammeter verifies proper operation of each string. Bruce Roe

                              PVtestLt.JPG
                              Last edited by bcroe; 06-27-2019, 02:46 PM.

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                              • #30
                                Originally posted by Spektre View Post

                                We all know how JPM feels about micros, so I'm not surprised he chimed in. Marky, based upon your adventures getting your system up and running, I'm surprised you're so anti-micro.

                                Enphase's Enlighten software lets you know exactly which micro is misbehaving. Replacing one on my flat roof with tilted panels would take me about 15 mins.
                                You are aware that your panels are putting DC onto the line as soon as you connect them, right? There is no AC output from your micro until you tell it to.
                                It's hot here in Phoenix, so putting string inverters in direct sunlight is not the greatest of ideas.
                                There's nothing special about Enphase trunk cable - it's only ~$1/ft, and you only need to run it from the end of your string to your combiner box/panel.

                                Anyways, to each his own. As a DIY person, micros for me are way easier.
                                I'm anti micro bc I just think it's a waste of money. As far as the software, you actually have to look at it to determine if there is a problem, most people after the first year or 2 wont even bother to look. Flat roof system isn't exactly typical of s roof mount setup.

                                every system is going to be different so where the inverter needs to go can obviously change. But is it going to be hotter under a panel on your flat roof or on the ground in direct sunlight? I'd usually say the roof is hotter but with panels blocking it's still going to be similar temps.

                                1$ a foot.... for trunk cable? I suppose the wiring scheme could be cleaner depending on the layout but I bought 1000 linear feet of pv wire and I think it was less than 300 and mc4 connectors are like 50 sets for 30$.

                                Yes I realize the DC lines are hot at the panels but you still have to connect the panels into the enphase inverter. Obviously mc4 connectors are designed to be safe. I'd personally make the connection at the inverter first in a string inverter scenario, then connect the panels in the string and then make the final connections to the wires running into the inverter.

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