Please help me decide on which way to go. (enPhase vs SolarEdge vs LG)

[Nekota]

This is a no brainer.

Solar Edge is by far the more efficient system.

I'm a Nabcep installer and have installed Enphase, Solar Edge, Schneider, Solar Bridge and SMA.
Clipping is bad news. If your clipping your not yielding all the power available.
I also seen in here where you think that running an inverter "hard" makes it more efficient. That is exactly backwards. The best inverter efficiency happens at the 80% point of the inverters rating. Going above that pushes the inverter into less efficient operation and reduces it life.
At wide open your down over 2% from the inverter peak efficiency.

Here where it gets cold a 250 watt panel will yield near 300 watts each. No enphase can handle that and it amounts to KWH's lost.
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You will never ever see a Enphase do this and the heat matters. The hotter the inverter the lower the power out.
I'll install a Solar Bridge before an Enphase. Micro inverters are the last choice and the least efficient over any central inverter system.

The Solar Edge arrays we installed has beat every other system out there for yearly yields. Including SMA and Fronius systems.
The micro inverter systems are always lower in yield. There easy to install and easier to expand but there the worst performing due to the 96% efficiency. Most modern central inverters are up around 98% efficient.

A 2% shift in efficiency on a 10kw array is 300KWh a year difference. If you live where it's cold then you need to allow head room in the inverter so you don't clip. Just look at the photo. Those are all 250 panels with some right at 300 watts. On a Enphase you'll never know what is really there.

No matter what you decide power clipping is Bad. You spent the money don't you want every drop of power ?

If someone is telling you that a Solar Edge is cheaper than an Enphase some one is feeding you hay. Solar Edge is the most expensive system to install and for good reason. Nothing else comes close.

And with the modular Maximizers it's just as easy to add to a Solar Edge as to an Enphase and online monitoring is built into every Solar Edge. No extra 400 dollar box is needed.
Enphase die. Never mind it's under warranty. Had a car like that. Broke all the time but it was under warranty. Well it didn't cost me but I got tired of it being in the shop all the time and driving a loaner. Give them time and you'll be on the roof pulling panels.

It's time to get the snake oils out of solar.

With PV panels installed in a series string some reports show there is a potential induced degradation (PID) that is claimed to be around 3% loss. With a microinverter system there is much less voltage and less PID so the gain in inverter efficiency is likely lost to the PID so the systems become equivalent over time. Another loss is soiling, I'm still waiting for a cost effective means to clean panels and keep the system at high operating efficiency. The soiling in my climate is relatively high with the dry summers and dew condensation that cakes the soil.

As for reliability, the M215 I have are operating without major failure, currently that would be 30 months for 20 panels which isn't that long. I have heard the M190 inverters have high field failures.

The biggest loss term I see is due to temperature of the PV panel. Every 2 degrees celsius drops the PV panel efficiency by 1% and little is said about making panels that operate at cooler temperatures. Given all the different sources of PV panel power losses, the loss from oversizing the PV panel to the size of the inverter is near the bottom of the % loss. I would put $ into getting more watts from the panel than from the inverter. The amount of time the inverter spends near clipping compared to the rest of the curve is much less. So I'm not convinced the Solar Edge is that much better or worse than Enphase. I do know the two factors for my decision to go with Enphase were the high voltage stress on the panels and the inverter lasting for the full 25 years. How long can the Solar Edge inverter run for before the central inverter has to be replaced?

[russ]

I'm a Nabcep installer

There is no such thing as a NABCEP installer - there is an individual that went through NABCEP training which doesn't mean much

[foo1bar]

With PV panels installed in a series string some reports show there is a potential induced degradation (PID) that is claimed to be around 3% loss. With a microinverter system there is much less voltage and less PID so the gain in inverter efficiency is likely lost to the PID so the systems become equivalent over time.

Sounds like sales pitch to me.

What is the potential (voltage) across the panel when it's setup in a string type inverter?
What is the potential (voltage) across the panel when it's setup in a microinverter system?
Answer?
They're the same, assuming that both are being operated at max-power-point.

So how about potential between the cells and the glass or the frames?
The string inverter does have higher difference between those.
It might be a 400-600V difference instead of ~30V.
Is that where this PID is having it's affect? the edges of the panels/cells?
And if so, is it more degradation on ungrounded arrays, positive grounded arrays, or negative grounded arrays?

How long can the Solar Edge inverter run for before the central inverter has to be replaced?

I'm guesstimating at least 10 years.
I've read on here that I could buy a warranty for 20 years for extra $300.

If someone is telling you that a Solar Edge is cheaper than an Enphase some one is feeding you hay.

I priced out doing solaredge and doing enphase for a 30 panel system.
Enphase was $4350 for just the inverters.
Solaredge was $1800 for optimizers and $1800 for the inverter.
Add in price for wiring (enphase has special cable that costs a little more)
And enphase envoy and software for per-panel tracking ($500 and $250)
And we're at >$1500

The flip side is now there is extra labor.
And I think that may be what you're referring to.
I think the optimizers and the microinverters are similar in labor. But solaredge requries someone to hang the inverter and wire it up - so that's extra labor and depending on your cost of labor that could easily remove the price advantage for solaredge... (I'm willing to work on my house for $100/hr, and I don't think it took me even 8 extra hours, much less 15)

[ButchDeal]

Sounds like sales pitch to me.

What is the potential (voltage) across the panel when it's setup in a string type inverter?
What is the potential (voltage) across the panel when it's setup in a microinverter system?
Answer?
They're the same, assuming that both are being operated at max-power-point.

Well it is actually difference between optimized and micro which should be no difference.

I'm guesstimating at least 10 years.
I've read on here that I could buy a warranty for 20 years for extra $300.

SolarEdge comes with a 12 year warranty on the inverter and you can upgrade to either 20 or 25 year.
The warranty on both the inverter and optimizers covers labor too.

[Nekota]

I would start by questioning the array configuration. If it is truly a side by side test, and 12 panels are used in the enphase array, why not use 12 in the Solaredge array?

They used 8 and 24 with two different inverter sizes, 3000 running at about 50% and the 6000 running at close to 100%. Given the efficiency of an inverter (I could only find SMA) peaks at 50% load this may be part of the reason for the sizing difference. The Enphase could have 17 units on a single array or trunk cable so not sure there was a reason for going with 12.

At least they tested the panels at same time with same location and produced data. I know in my own system there is several percent differences between the panels in the array. Those panels which are on the leading edge with prevailing breeze get cooler air than the downstream ones and I attribute the differences in output to the temperature of the panel which is hotter than the inverter but correlated to the microinverter beneath it.

Thanks for your reply but the number of panels doesn't invalidate the results from what I can tell. Any other things I'm missing?

[Nekota]

Sounds like sales pitch to me.

What is the potential (voltage) across the panel when it's setup in a string type inverter?
What is the potential (voltage) across the panel when it's setup in a microinverter system?
Answer?
They're the same, assuming that both are being operated at max-power-point.

So how about potential between the cells and the glass or the frames?
The string inverter does have higher difference between those.
It might be a 400-600V difference instead of ~30V.
Is that where this PID is having it's affect? the edges of the panels/cells?
And if so, is it more degradation on ungrounded arrays, positive grounded arrays, or negative grounded arrays?

PID is probably sodium ion diffusion controlled and the literature indicates negative grounded systems are associated with PID. It is more likely driven by voltage difference and where the voltage delta is the greatest. Advanced Energy has some literature about PID, ion diffusion, and ways to check for it. In my understanding, ion mobility is driven by the voltage gradient so a 400V - 600V system would degrade faster than a 40V system. In fact this is one of the ways to check for PID by looking at OC Voltage as a function of panel position in the string. Sources of sodium come from the glass, the antireflection coating, the frame and encapsulation materials. In semiconductor fabs, sodium ions contamination is usually monitored with CV wafers, I have no idea what is done in solar cell fabs to control contamination. Here is a link to the Advanced Energy literature -

http://solarenergy.advanced-energy.com/upload/File/White_Papers/ENG-PID-270-01%20web.pdf

You can search for other sources of PID discussions. My point is the diffusion is increased by voltage and strings of PV panels will have more voltage (500) than a single panel (40). I will add the PID can occur with 40V as well so don't depend on low voltages as the corrective solution to PID.

[AaronG]

For like 2 pages, we are pretty off topic, right?

[russ]

You mean 2 pages of wild assed guesses and conjecture?

[chuckgm3]

I consider myself a fairly bright guy and this **** is giving me a headache. I do think as someone mentioned that with my TOU plan, it's probably a good idea to downsize to a 70-75% system. I'll crunch the numbers on that and see what I get. As for the EP vs SE, I still have no idea. I'll see if I can get a design with more favorable azimuth and fewer panels before I continue.

[foo1bar]

As for the EP vs SE, I still have no idea.

From what I can tell either one will handle shading pretty well.
I went with Solaredge - you can see my comments above in the thread about how I see them compare.
If you're doing professional install, then it might change the balance some towards enphase because it's (slightly) easier to install, so might be a little cheaper.

Good luck.