Benefits of Solaredge vs. string inverter for non-shaded

[solarix]

My two identical arrays were originally one 24 panel system running on a 5kW Xantrex inverter. Trina 230w panels purchased all together on the same pallet. Because I'm an installer, I had a customer wanting to upgrade from a 3.3kW system to a 5kW system and through a whole series of events I ended up trading him my 5kW for his 3.3kW Xantrex and splitting my array - putting a SolarEdge on the other half as I was curious to see just how good it was. I did try swapping the arrays and saw no difference. Also (as a result of all the failures we experienced with the early SolarEdge version) I had a SolarEdge rep come visit us and showed him my head to head comparison and he could not do much more than smile. I think the conversion losses from multiple individual optimizers are higher than in one central string inverter and these losses blow any gaines made from optimization. On my two systems, the SolarEdge does better at first when the sun comes up, then through the day - the Xantrex gets ahead, and in late afternoon the Solaredge tries to catch up but never quite gets there. Anyway, the difference is slight and I can tell you for sure that optimizer systems are not worth it unless you have serious shading issues. On my system, the SolarEdge inverter has been reliable (so far) but have had to replace two of the Powerboxes (now they call them optimizers). Out of the 30 or so SolarEdge systems I installed back in the 2010 time frame, I've had 5 inverter failures (two of which literally blew up) and at least 12 Powerbox failures. All this was done under warranty, but of course - they did not compensate us for the time involved, not to mention the considerable customer loss of confidence. I really like the SolarEdge design concept - but they just did not quite get the manufacturing quality needed.

[J.P.M.]

My two identical arrays were originally one 24 panel system running on a 5kW Xantrex inverter. Trina 230w panels purchased all together on the same pallet. Because I'm an installer, I had a customer wanting to upgrade from a 3.3kW system to a 5kW system and through a whole series of events I ended up trading him my 5kW for his 3.3kW Xantrex and splitting my array - putting a SolarEdge on the other half as I was curious to see just how good it was. I did try swapping the arrays and saw no difference. Also (as a result of all the failures we experienced with the early SolarEdge version) I had a SolarEdge rep come visit us and showed him my head to head comparison and he could not do much more than smile. I think the conversion losses from multiple individual optimizers are higher than in one central string inverter and these losses blow any gaines made from optimization. On my two systems, the SolarEdge does better at first when the sun comes up, then through the day - the Xantrex gets ahead, and in late afternoon the Solaredge tries to catch up but never quite gets there. Anyway, the difference is slight and I can tell you for sure that optimizer systems are not worth it unless you have serious shading issues. On my system, the SolarEdge inverter has been reliable (so far) but have had to replace two of the Powerboxes (now they call them optimizers). Out of the 30 or so SolarEdge systems I installed back in the 2010 time frame, I've had 5 inverter failures (two of which literally blew up) and at least 12 Powerbox failures. All this was done under warranty, but of course - they did not compensate us for the time involved, not to mention the considerable customer loss of confidence. I really like the SolarEdge design concept - but they just did not quite get the manufacturing quality needed.

This is good data, and pretty valuable as a real world comparison of actual output. There may be things encountered in the future in either the methodology, the equipment or the data that may cause some reexamination of the results, but that does not retract from the value of what's been done so far. Whether or not everyone agrees with the conclusions doesn't matter too much. What's important is the data and its quality. Interpretation of what it all means followed by improvements are what counts. There's nothing like real world data that's well gathered and documented.

FWIW, IMO, nicely done.

[rsilvers]

http://www.lg.com/us/commercial/sola...lg-LG310N1C-G4 is +3% / 0-%

http://www.sunpreme.com/wp-content/u...le-Rev-1.3.pdf is +5% / -3%.

What's a +5W / -0W example?

Here is a +-5%:

http://us.sunpower.com/sites/sunpower/files/media-library/data-sheets/ds-e20-series-435-solar-panel-datasheet.pdf

Here is a +5% - 0%:

http://us.sunpower.com/sites/sunpower/files/media-library/data-sheets/ds-e20-series-327-residential-solar-panels.pdf

[DanKegel]

Out of the 30 or so SolarEdge systems I installed back in the 2010 time frame, I've had 5 inverter failures (two of which literally blew up) and at least 12 Powerbox failures.

Good data. Do you have any data on more recent SolarEdge equipment reliability?

[solarix]

I kind of quit using SolarEdge because of all the problems, but as far as I know the new versions are pretty reliable.
Now that SMA's new string inverters are quite good at multiple orientations, I rarely use SolarEdge. Better to do whatever it takes to get full sun than to mitigate shade with a band-aid....

[DaveDE2]

On a system that large, and assuming say 310W panels, you're talking about 80 or so panels on each roof face. You're probably going to have to remove one or two panels to get to a bad optimizer when it fails, something to consider maintenance-wise. May or may not be a big deal depending on how steep the roof is. With 160 panels and optimizers it will probably happen on the order of every two years or so (assuming optimizer 300 year MTBF), again, may or may not be a big deal. Alternatively, with only diodes on the roof, a failure will be less likely to ever happen over 20-30 years or so. Just saying.

[sensij]

http://www.lg.com/us/commercial/sola...lg-LG310N1C-G4 is +3% / 0-%

http://www.sunpreme.com/wp-content/u...le-Rev-1.3.pdf is +5% / -3%.

What's a +5W / -0W example?

Look at panels made by Solarworld, Canadian Solar, and Q-Cells, to name a few of the checked before I posted.

[inetdog]

I see +5W/-0W as the power tolerance a lot more often than i see +5%/-0%. What panels are you looking at? Even with that tolerance, the chance that two entire arrays would be built on opposite ends of the tolerance isn't the most likely explanation for the observed power output difference, in my opinion.

Statistics tells us that for randomly selected panels an individual panel variation of 5% will lead to a much smaller variability in an array.
if you have 9 panels in an array the likely variation would be roughly 5%/3, or 1.66%