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RegGuheert
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Re: Microinvertors vs. Single invertors, what's the differen

Thu Oct 09, 2014 7:09 am

I also think there is a considerably lower risk of a fire with microinverters versus string inverters:





Enphase Fire safety handout

Also, unfortunately, the existence of string inverters in the marketplace has firefighters around the world nervous about fighting fires in buildings containing PV panels. While the string inverters have cutoffs, the high voltage of the string still exists in the wiring. As such, firefighters are leery of getting near them.

The situation is markedly different with microinverters. Once the disconnect on the side of the house is thrown, there is no more high voltage on the roof, period.

Note in following firefighter training video regarding PV systems, the trainer tells the firefighters the following facts which area ONLY true for string-inverter-based PV systems:
- DC voltages on the roof are between 120V and 600V.
- High voltages are on the roof whenever the sun shines.
- High voltages are even present just from the lights used to fight fires at nighttime.
Unfortunately, he does not inform the firefighters that there is another type of PV system which does not pose ANY of these safety risks and that the system is fully disabled when the disconnect is thrown. Then only low-voltage DC exists on the roof.

RegGuheert
2011 Leaf SL Demo vehicle
10K miles: Apr 14, 2013, 20K miles (55.7Ah): Aug 7, 2014, 30K miles (52.0Ah): Dec 30, 2015, 40K miles (49.8Ah): Feb 8, 2017, 50K miles (47.2Ah): Dec 7, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

wongfeihong187
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Re: Microinvertors vs. Single invertors, what's the differen

Thu Oct 16, 2014 8:16 am

Crap, looks like the installer didn't connect the PV correctly, thus the fire. I'm going with the SMA sunny boy 500tl single invertor for my 5.4kw system. The costs of the microinvertors doesn't outweigh the risks of single invertors :).

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RegGuheert
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Re: Microinvertors vs. Single invertors, what's the differen

Thu Oct 16, 2014 9:42 am

wongfeihong187 wrote:I'm going with the SMA sunny boy 500tl single invertor for my 5.4kw system. The costs of the microinvertors doesn't outweigh the risks of single invertors :).
Of course the microinverters are warranted for five times as long as the SunnyBoy. For approximately an additional $400 more, you can reduce that gap to 25 years (microinverter) versus 15 years (SunnyBoy).
RegGuheert
2011 Leaf SL Demo vehicle
10K miles: Apr 14, 2013, 20K miles (55.7Ah): Aug 7, 2014, 30K miles (52.0Ah): Dec 30, 2015, 40K miles (49.8Ah): Feb 8, 2017, 50K miles (47.2Ah): Dec 7, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

wongfeihong187
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Re: Microinvertors vs. Single invertors, what's the differen

Thu Oct 16, 2014 11:11 am

RegGuheert wrote:
wongfeihong187 wrote:I'm going with the SMA sunny boy 500tl single invertor for my 5.4kw system. The costs of the microinvertors doesn't outweigh the risks of single invertors :).
Of course the microinverters are warranted for five times as long as the SunnyBoy. For approximately an additional $400 more, you can reduce that gap to 25 years (microinverter) versus 15 years (SunnyBoy).



Yes, but I'm not planning on staying past 10 years in my current home.

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RegGuheert
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Re: Microinvertors vs. Single invertors, what's the differen

Mon Oct 27, 2014 6:54 am

Here is a direct production comparison test between Enphase M215s versus SunnyBoy SB3000HF-US. The conclusion of the study indicates that even though the Enphase microinverters have sightly lower CEC Weighted Inverter Efficiency than the SunnyBoys, they harvested slightly MORE energy during the test. This was true even though there was no shading involved in this test. The conclusion in this study is that the Enphase inverters harvested more energy during periods of low light, resulting in higher total production.
RegGuheert
2011 Leaf SL Demo vehicle
10K miles: Apr 14, 2013, 20K miles (55.7Ah): Aug 7, 2014, 30K miles (52.0Ah): Dec 30, 2015, 40K miles (49.8Ah): Feb 8, 2017, 50K miles (47.2Ah): Dec 7, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

NeilBlanchard
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Re: Microinvertors vs. Single invertors, what's the differen

Mon Oct 27, 2014 10:02 am

Micro inverters are better in mixed light situations: if one panel goes into a shadow, it doesn't drag down the whole array. You still get output from each panel that is getting light.

Same goes for failures - lose one micro inverter and you lose that one panel.

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Wennfred
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Re: Microinvertors vs. Single invertors, what's the differen

Tue Oct 28, 2014 2:31 pm

In April of 2007, I went with 2 strings, 2 xantrax 3.8's inverters & 46 Sharp panels rated at 170 Watts each, back then there were no micro inverter systems, my solar system has been trouble free since.

Within the last few years most of my friends went with Enphase & other micro inverter systems, they have had to get a few micro inverters replaced. I'm guessing due to heat issues under the panels, they get really hot. Most installers seem to push the single string system due to this problem. So do your research on the failure rates of these micro inverters.


Fred
MFG: FEB 2011, Red Recd 08/10/13 @ 19600 Miles
"Eco Mode" only. 06/24/15 - 9 CB @ 43,000mi 100% charge: GIDS=199, S=95.37, C=46.76, H=50.51 Lost 1st CB at 26300, 2nd CB 34274 3rd CB 43000 miles

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RegGuheert
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Re: Microinvertors vs. Single invertors, what's the differen

Tue Oct 28, 2014 2:39 pm

Wennfred wrote:So do your research on the failure rates of these micro inverters.
I've already done that for you for Enphase microinverters: Enphase field MTBF: M190: ~60 Years M215: ~1300 Years. Now if only we had something to compare it against which gave MTBFs for string-inverter systems.

BTW, IIRC, the early Xantrex string inverters had terrible failure problems. It seems they gave almost the entire string inverter market to SMA, which has produced extremely reliable string inverters in their SunnyBoy line. It's good to hear that yours is working well!
RegGuheert
2011 Leaf SL Demo vehicle
10K miles: Apr 14, 2013, 20K miles (55.7Ah): Aug 7, 2014, 30K miles (52.0Ah): Dec 30, 2015, 40K miles (49.8Ah): Feb 8, 2017, 50K miles (47.2Ah): Dec 7, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

WisJim
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Re: Microinvertors vs. Single invertors, what's the differen

Fri Oct 31, 2014 6:50 pm

No one that I know has had any problems with Enphase microinverters--maybe because of cooler climate in the Midwest? And many of the systems that I know of are ground or pole mounted, so have good air circulation behind the panels On the other hand, my Trace (later Xantrex, now Schneider) inverter on the older part of my system is over 15 years old and the only problem was lightning surge damage probably caused by incorrect grounding.

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RegGuheert
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Re: Microinvertors vs. Single invertors, what's the difference?

Thu Apr 12, 2018 8:13 am

Enphase is promoting the safety aspects of their microinverter products in their latest blog post:
Enphase wrote:And that’s exactly what 22 fire stations of the rural fire brigade in and around Toowoomba in Queensland have done. Each station is now the proud owner of an Enphase Microinverter System on its roof to harvest clean energy from the sun in the safest possible way. The four main reasons why the rural fire brigade chose Enphase Microinverters over any other system are pretty obvious. They wanted:

- The safest system due to its all-AC architecture
- The highest quality system due to components tested in the harshest climates
- The best value system that maximises self-consumption and leads to great savings on quarterly electricity bills
- The smartest system due to online monitoring and fleet management of all 22 systems on a single platform
RegGuheert
2011 Leaf SL Demo vehicle
10K miles: Apr 14, 2013, 20K miles (55.7Ah): Aug 7, 2014, 30K miles (52.0Ah): Dec 30, 2015, 40K miles (49.8Ah): Feb 8, 2017, 50K miles (47.2Ah): Dec 7, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

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