Qcells vs S-Energy

[moneymm22]

Looking to pull the trigger soon on one of these deals from two different companies for my house.

OPTION A:
Panels:59
Qcells Q.PEAK DUO BLK ML-G10+ 405
Inverters:59
Enphase Energy Inc. IQ8PLUS-72-M-US
System Size:23.89
KW Production:27,399 KWH

vs

OPTION B:
SL6554BHJ400V
Brand- S-Energy
Wattage- 400 Watts each
23,600 Watt System
Performance- This system will produce approximately
27,734 kWhr's per year


There is a difference in total price, but ill leave the money out of it for now. Are these comparable panels? how much actual less production will one give me at the end of 25 years?

[moneymm22]

was doing some reading on here of micro inverters (which everyone has quoted me) and a string inverter. Since i have so many panels, is it nuts to have 59 micro inverters up on my roof? with 59 potential things to go wrong.

[bcroe]

Micro inverters can be effective with significant shading. They
are no brainer install designs, but have a long list of negatives.
Bruce Roe

[solardreamer]

You could go with string inverters but then you will likely have just as many rooftop devices for optimizer and/or rapid shutdown.

One thing about Enphase is that you don't need the iQ8 (significant premium over the iQ7) unless you want sunlight only backup which requires several $$K's additional equipment. Installers seem to always propose the iQ8 even when sunlight backup is not necessary or possible (i.e. without the required additional equipment).

[J.P.M.]

was doing some reading on here of micro inverters (which everyone has quoted me) and a string inverter. Since i have so many panels, is it nuts to have 59 micro inverters up on my roof? with 59 potential things to go wrong.

Yes. Electronics in a tough (read hot) environment that's mostly hard to get at can be a problem. Probably easier to install micros but higher probability for problems down the line. Also, micros violate the KISS principle big time.

Questions: What's your location and what's the array's tilt and azimuth ? Any shade on the proposed array ?
Reason for asking: Production (kWh/yr. production per installed STC W) seems low.
You sure this makes economic sense ?
Conservation efforts before PV is always a better way to cost effectiveness.

[moneymm22]

Yes. Electronics in a tough (read hot) environment that's mostly hard to get at can be a problem. Probably easier to install micros but higher probability for problems down the line. Also, micros violate the KISS principle big time.

Questions: What's your location and what's the array's tilt and azimuth ? Any shade on the proposed array ?
Reason for asking: Production (kWh/yr. production per installed STC W) seems low.
You sure this makes economic sense ?
Conservation efforts before PV is always a better way to cost effectiveness.

Long Island NY
i have have several roofs, these will be placed on 5 different roofs. some face south, others face east. no real shade to speak of on any of the proposed locations for the 59 panels.

i am not using some of the roofs b/c they are under shade or face west.
def makes economic sense. i pay 7k a year in electricity bills. if i can lower the 588 bill to a 400 dollar payment and pocket some tax credits, ill be ahead for sure.

[bcroe]

Panels with different orientations or serious shading should not
be placed in the same string. If each string is itself consistent,
it may be placed in parallel with other strings of the same MPPT
voltage but different orientations on a single inverter. Bruce Roe

[GoingElectric]

Also, micros violate the KISS principle big time.

How so?
For house roof systems they have net advantages, especially with multiple facings and various shade issues.

On larger single face / direction installs I do agree string is superior.

[GoingElectric]

Looking to pull the trigger soon on one of these deals from two different companies for my house.

OPTION A:
Panels:59
Qcells Q.PEAK DUO BLK ML-G10+ 405
Inverters:59
Enphase Energy Inc. IQ8PLUS-72-M-US
System Size:23.89
KW Production:27,399 KWH

There is this non-BLK version too
Q.PEAK DUO ML-G10+

the BLK versions add cosmetics to improve the look, but results in a small performance loss which will add up over the decades.

[J.P.M.]

How so?
For house roof systems they have net advantages, especially with multiple facings and various shade issues.

On larger single face / direction installs I do agree string is superior.

Well, since you're asking:

For starters, get over the idea that residential PV is always a good solution/path to a lower electric bill or that it's always a sound long term investment. Residential PV systems are not always a slam duck as the most cost-effective way to lower an electric bill.
One usual impediment to optimum cost effectiveness is less than optimal roof or property orientation. One giveaway to that is the use of multiple roof orientations. Such multiple roof orientations may be viewed as necessary but what's almost always ignored is the penalty incurred by trying to make a silk purse out of a sow's ear by the use of less than optimal orientations in the often mistaken or at least un/ill informed opinion/belief that PV is the right choice.
I've seen a lot of that type of thinking get transferred onto a property.

Reality as I believe I've seen it many times: In spite of what peddlers eager to close a sale, and what their mostly uninformed greenwash media shills will tell you, or what your mostly ignorant neighbors will anecdotally blather about doing by no more than parroting what their peddlers spewed out, PV is not guaranteed to be well engineered much less cost effective.

Now, about micros and optimizers. They are sensitive electronics. They do not do well in harsh environments like those where expose to heat/cold/the elements/critters/etc., and/or in inaccessible or hard to get at places can occur. Residential roofs are good examples of places with those characteristics.
There's a reason a roof is about the loneliest place in a home. BTW, how often do you see your neighbors (or anyone for that matter) on a roof ?
That's because it's a harsh environment.

So, starting out by putting devices that are already sensitive to the elements in harsh environments can only increase the probability of failures, and then adding increased failure rate probability due to multiple redundancy (a bunch of micros instead of one, maybe two string inverters in a protected garage for example) in mostly inaccessible environment seems to make little sense to me, at least from an engineering standpoint.

Now, micros and optimizers do generally have longer warranties than string inverters and that's a good thing, especially given the probability of higher inverter failure rates in a system if only due to the increased number of components.
Also, enjoy replacing a micro including the likely removal of adjacent panels for access while hoping all the (redundant) wiring gets replaced correctly.
And, BTW, make sure the micro warranty covers labor while you're at it. Not all do.

More BTW, string inverter systems usually or at least often cost a bit less than microinverter systems.
If you're worried about warranty on a string inverter being only 12 years or so vs. 25 for a micro, design the system for a string inverter and buy a spare inverter system with the savings. Even if the savings don't cover the cost of the spare inverter, you'll still have a better engineered system with cheap insurance.

Take what you want of the above. Scrap the rest.

[bcroe]

Micro inverters have a problem of transmiting power at lower
voltage the entire distance. This certainly will increase the
cost-efficiency equation. And I cannot quite visualize running
all those AC outlets outside, 1 per panel. The string wiring is
way simpler, 1 pair for a string of perhaps 12 panels.

If you want to use antennas for communication, anything below
UHF is going to be sensitive to noise. String inverters can spend
the money to filter their noise, failing that more filtering could be
added.

The micros are out of reach, right where you do not want noise,
and can only afford much lower investment in filtering per unit.
Bruce Roe

[GoingElectric]

Well, since you're asking:

For starters, get over the idea that residential PV is always a good solution/path to a lower electric bill or that it's always a sound long term investment. Residential PV systems are not always a slam duck as the most cost-effective way to lower an electric bill.
One usual impediment to optimum cost effectiveness is less than optimal roof or property orientation. One giveaway to that is the use of multiple roof orientations. Such multiple roof orientations may be viewed as necessary but what's almost always ignored is the penalty incurred by trying to make a silk purse out of a sow's ear by the use of less than optimal orientations in the often mistaken or at least un/ill informed opinion/belief that PV is the right choice.
I've seen a lot of that type of thinking get transferred onto a property.

Reality as I believe I've seen it many times: In spite of what peddlers eager to close a sale, and what their mostly uninformed greenwash media shills will tell you, or what your mostly ignorant neighbors will anecdotally blather about doing by no more than parroting what their peddlers spewed out, PV is not guaranteed to be well engineered much less cost effective.

Now, about micros and optimizers. They are sensitive electronics. They do not do well in harsh environments like those where expose to heat/cold/the elements/critters/etc., and/or in inaccessible or hard to get at places can occur. Residential roofs are good examples of places with those characteristics.
There's a reason a roof is about the loneliest place in a home. BTW, how often do you see your neighbors (or anyone for that matter) on a roof ?
That's because it's a harsh environment.

So, starting out by putting devices that are already sensitive to the elements in harsh environments can only increase the probability of failures, and then adding increased failure rate probability due to multiple redundancy (a bunch of micros instead of one, maybe two string inverters in a protected garage for example) in mostly inaccessible environment seems to make little sense to me, at least from an engineering standpoint.

Now, micros and optimizers do generally have longer warranties than string inverters and that's a good thing, especially given the probability of higher inverter failure rates in a system if only due to the increased number of components.
Also, enjoy replacing a micro including the likely removal of adjacent panels for access while hoping all the (redundant) wiring gets replaced correctly.
And, BTW, make sure the micro warranty covers labor while you're at it. Not all do.

More BTW, string inverter systems usually or at least often cost a bit less than microinverter systems.
If you're worried about warranty on a string inverter being only 12 years or so vs. 25 for a micro, design the system for a string inverter and buy a spare inverter system with the savings. Even if the savings don't cover the cost of the spare inverter, you'll still have a better engineered system with cheap insurance.

Take what you want of the above. Scrap the rest.

Solid points for sure.

Lets put the install justification aside (an excellent discussion topic).

String has a single point of failure issue, and very few will have the planning let alone skill to get a spare String and able to replace it. Yes the cost and efficiency are favorable, plus ground level access to the core unit, but redundancy is lost. There also the "weakest link" weakness, performance of 1 panel will impact total output.

Yes, a failed micro will be hard to replace, even dangerous on steep roof installs. Also depending on system size more expensive. Yet on installs with multiple faces and shading issues it is a superior product.

This would be actually a good matrix plot to make.

[GoingElectric]

Micro inverters have a problem of transmiting power at lower
voltage the entire distance. This certainly will increase the
cost-efficiency equation. And I cannot quite visualize running
all those AC outlets outside, 1 per panel. The string wiring is
way simpler, 1 pair for a string of perhaps 12 panels.

If you want to use antennas for communication, anything below
UHF is going to be sensitive to noise. String inverters can spend
the money to filter their noise, failing that more filtering could be
added.

The micros are out of reach, right where you do not want noise,
and can only afford much lower investment in filtering per unit.
Bruce Roe

What is frequency and DB of radio noise produced by Micros?

[bcroe]

What is frequency and DB of radio noise produced by Micros?

The frequency is zero to UHF, falling off with frequency. If you want DB,
set up your favorite micro and select a distance for your measurement.
It will certainly vary depending on how good an antenna the PV wiring is.

To get a general feeling take an AM portable radio and set it between
stations. Move it around a hard working micro array. TV low band will
probably be affected, FM less. HAM RADIO will suffer.
Bruce Roe

[J.P.M.]

Solid points for sure.

Lets put the install justification aside (an excellent discussion topic).

String has a single point of failure issue, and very few will have the planning let alone skill to get a spare String and able to replace it. Yes the cost and efficiency are favorable, plus ground level access to the core unit, but redundancy is lost. There also the "weakest link" weakness, performance of 1 panel will impact total output.

Yes, a failed micro will be hard to replace, even dangerous on steep roof installs. Also depending on system size more expensive. Yet on installs with multiple faces and shading issues it is a superior product.

This would be actually a good matrix plot to make.

String systems do indeed have a single point system failure potential (but that's not necessarily all bad).
And too, the other side of that coin that I've seen is that micros and optimizers have a more insidious potential problem.
An example: Say a rooftop micro equipped system has 24 panels. Also say that like most residential system owners, they (the new system owners) are inattentive to system condition meaning that after about a month or less of watching the system output (which they know nothing about in the first place), they stop looking at system output. And, vendor monitoring is spotty at best and weather is reasonably variable - all of which contributes to even less of a chance of spotting a problem by looking at output even if owners knew what to look for and did bother to monitor.

Now, say a micro dies for some reason. Under the conditions described above, what do you think the probability of that failure being noticed ? Yea.
So, 1/24 of the said array output disappears and that loss goes unnoticed. For how long ? What happens if another micro fails? How many need to fail until the problem gets noticed ?

That's happened a few times in my HOA. One failure I know of was found when the system was upsized a bit. Don't know when the failure occurred. Another micro failure on another system got found when water got in a j-box and shut things down. Neither vendor caught the original micro failure, one of the vendors was and may well still be out of business although they still have a website of sorts (Sullivan Solar).

Anyway, seems to me that if a string inverter crapped out it would have a pretty good probability of being noticed when the next electric bill arrived. Not fool proof monitoring but more likely to be discovered than a smaller, incremental failure.

BTW, as long as I've been involved in PV systems in my HOA - ~ 14 years and counting (and about HOA 175 + installs at this point) no string inverters have failed. In contrast with that, more than a few micros and optimizers have failed. That ratio seems about in line with what we've been reading on this forum for as long as I've been a member (08/2013); lots of talk around here about failures and problems with micros and optimizers compared with relatively few discussions about problems with string inverters.

As a practical matter, I'd rather have one potential failure point for the system in a place where (BTW) I can get at it more easily than one for each panel on a roof - especially when considering the possibility of additional problems brought on by disturbing other nominally operating system components and wiring needed to get at a problem micro or optimizer, a situation that will arise every time a micro of optimizer fails or needs service. Seems like there's avoidable, self-inflicted and piggy back KISS violations here to me.

As for initial install justification I'd agree that's a bigger discussion but not a separate one.
Here's my thinking FWIW: One big item I hear and read about all the time as a justification for micros or optimizers is that they are a way to deal with system shading. My reply to that is that if shading is a problem, the array is either in the wrong place or the site is not economically or practically suitable for a PV application in the first place, but the potential owners are ignorant of the practical or economic reasons why and got duped by peddlers, their media shills or their own keep up with the Jones herd mentality.
If the bottom-line reason for getting residential PV is to reduce an electric bill, IMO only, of those 175 installs I mentioned most owners would have been money ahead if they'd skipped the PV entirely or at least until some serious conservation efforts happened before any solar generation was added.
Micros and optimizers, among other not so nice characteristics I've mentioned, also make a peddler's job of selling a bad application and B.S.ing customers easier by telling their marks that micros and optimizers are a quick and easy solution to a poor application due to a shading problem.

Take what you want of the above. scrap the rest.