Solaredge inverter sizing?

[russ]

The warranty is through Solaredge. It's $303 for 20 years, I THINK $485 for 25. The 20 seems a good deal for something with a 12 year warranty. You just fill out a form after the install & mail them a check.

And if they are around in 15 years when the inverter fails they back it up - if they aren't? Some panel manufacturers offer a warranty backed by insurance that will pay even if they go belly up.

[Bikerscum]

I can't see your exact panel orientation, but here is how it would work here. Your 18 panels
are rated 4950W. If the 2 east facing panels were at 100% and 550W, I'd expect 10% of that
from the west facing 2 panels, 55W. Total is 5555W, with 97% inverter & DC wiring efficiency,
this amounts to 5388W output. In reality the E, S, and W facing will never be at peak anywhere
near the same time, so you probably will never be near clipping.

That is my feeling also. It seems like a safe bet even if the theory is crap.

[Bikerscum]

I plan on spending the $303 for a 20 year warranty regardless of which size I get, so lifespan isn't an issue. Probably a good idea - is it a 3rd party insurance type of warranty? The party themselves may well not be around.

Comments in bold within the text

The warranty is through Solaredge. It's $303 for 20 years, I THINK $485 for 25. The 20 seems a good deal for something with a 12 year warranty. You just fill out a form after the install & mail them a check.

The thing that keeps eating at me in this is that Solaredge advises to buy a cheaper inverter. If it was the other way around I'd write it off as marketing hype or something, but they have nothing to gain & $$ to lose by doing this.

[russ]

The early startup is bunk. My inverters start up as soon as it is light, but they don't put out significant power for an hour or so. Same in reverse at sunset. Bruce Roe

Same as the claim for some wind turbines that they start with very low wind speeds - since there is little power in those low speed winds the power generated is zip.

[bcroe]

Ok, so here's my latest 100% mostly firm decision...
Best case scenario, I'll have 18 panels facing south, 2 east, and 2 west. The total system size is 6.05k with Solaredge optimizers. The Solaredge 5k inverter is rated @5450 max @240v. Solaredge recommends (and will warranty) you over driving it up to 125%, or 6.25k. (Interesting to note here that the 6k model is the ONLY one in the Solaredge lineup that is NOT rated for more max power than it's label rating.)

The theory I keep hearing is that the smaller, overdriven inverter will startup sooner, making more power in low light conditions. Given that 4 of my panels will point east/west, I think this will work for me. In any case, I can't see my system putting out over 5450 and getting clipped.

I can't see your exact panel orientation, but here is how it would work here. Your 18 panels
are rated 4950W. If the 2 east facing panels were at 100% and 550W, I'd expect 10% of that
from the west facing 2 panels, 55W. Total is 5555W, with 97% inverter & DC wiring efficiency,
this amounts to 5388W output. In reality the E, S, and W facing will never be at peak anywhere
near the same time, so you probably will never be near clipping.

The early startup is bunk. My inverters start up as soon as it is light, but they don't put out
significant power for an hour or so. Same in reverse at sunset. Bruce Roe

[russ]

The theory I keep hearing is that the smaller, overdriven inverter will startup sooner, making more power in low light conditions. The Easter Bunny and the Tooth Fairy are equally true.

I plan on spending the $303 for a 20 year warranty regardless of which size I get, so lifespan isn't an issue. Probably a good idea - is it a 3rd party insurance type of warranty? The party themselves may well not be around.

Comments in bold within the text

[Bikerscum]

Ok, so here's my latest 100% mostly firm decision...

Best case scenario, I'll have 18 panels facing south, 2 east, and 2 west. The total system size is 6.05k with Solaredge optimizers. The Solaredge 5k inverter is rated @5450 max @240v. Solaredge recommends (and will warranty) you over driving it up to 125%, or 6.25k. (Interesting to note here that the 6k model is the ONLY one in the Solaredge lineup that is NOT rated for more max power than it's label rating.)

The theory I keep hearing is that the smaller, overdriven inverter will startup sooner, making more power in low light conditions. Given that 4 of my panels will point east/west, I think this will work for me. In any case, I can't see my system putting out over 5450 and getting clipped.

I plan on spending the $303 for a 20 year warranty regardless of which size I get, so lifespan isn't an issue.


Yes?

Please?

[J.P.M.]

That jives with their technical paper on the subject, but still doesn't explain why (neither does the paper).

I'm also a little suspicious about the average temp thing. I mean, where I live the historical average year round is 73. But, it's in the 50's in January & easily 110 in July. Why would the average matter? Seems an overdriven inverter would not be happy in the summer here?

Pretty confusing, but I've heard the overrating thing from 3 different installers now.

FWIW: On sunny days, with low wind velocity, my ambient roof temp. runs about 20 deg. F. higher than the air temp. on the back porch. Again, depending on wind velocity, direction and solar irradiance, the panel temps run ~~ 40 to 50 deg. F. or so hotter than the roof ambient air temp. If the micros are attached to the panels, my guess is they'll run somewhere between the roof ambient air temp. and the panel temp. So, in my case, if 70 deg. air-->> ~90 deg. roof air -->> ~ 140 deg. panel temp. -->> micro temp ?? -->> (90+140)/2 = 115 deg. F ?? Maybe a bit less on a SWAG.

[Bikerscum]

He said the inverters work better and produce more when over driven. If your average high temp is below 76 degree you can over power by as much as 35%

That jives with their technical paper on the subject, but still doesn't explain why (neither does the paper).

I'm also a little suspicious about the average temp thing. I mean, where I live the historical average year round is 73. But, it's in the 50's in January & easily 110 in July. Why would the average matter? Seems an overdriven inverter would not be happy in the summer here?

Pretty confusing, but I've heard the overrating thing from 3 different installers now.

[russ]

He said the inverters work better and produce more when over driven. If your average high temp is below 76 degree you can over power by as much as 35%

Get that in writing - he has things a bit turned around.

[Lews411]

Thanks for the info. Curious... did the Solaredge guy say WHY the smaller inverter would make more power?

He said the inverters work better and produce more when over driven. If your average high temp is below 76 degree you can over power by as much as 35%

[Bikerscum]

Just installed solaredge system worked with solaredge field rep. He told me they always prefer to over drive the inverter about 15 to 25 percent.
I installed 84 Solarworld 280 watt panels feeding 2. 10 KW inverters they did not want to use the 11.4 said production would be better with the 10's
Pvwatts calculator shows I should make about 108 per day I have been running about 140 with the solaredge.

Thanks for the info. Curious... did the Solaredge guy say WHY the smaller inverter would make more power?

[Lews411]

Solaredge

My system will be 6k, with 22 Solarworld 275 panels, Solaredge optimizers. The installer says he will use a 5k (SE5000A-US) inverter. This doesn't make sense to me... shouldn't it be 6k? I've read a bit on oversizing, but I'm a bit leary. Is there any advantage other than price of going with the smaller inverter? Any disadvantage of going with the 6k? Seems like the amperage on the 5k would be pushing the limits?

Thanks as always.

Just installed solaredge system worked with solaredge field rep. He told me they always prefer to over drive the inverter about 15 to 25 percent.
I installed 84 Solarworld 280 watt panels feeding 2. 10 KW inverters they did not want to use the 11.4 said production would be better with the 10's
Pvwatts calculator shows I should make about 108 per day I have been running about 140 with the solaredge.

[thejq]

Just got a new toy to play with... the Solaredge Site Designer software. Interesting that it recommends either a single 5k inverter, or 2 3k inverters for my system, and a 121% oversizing.

In the Software, if you manually deselect SE5000, it should recommend SE6000. Compare the output numbers between this and SE5000. If the same, you should pick SE6000 esp. with no price difference. I think the Software also pick the lower price as well. Theoretically with SE6000, since you're not running at full capacity all the time, it should help with longevity.

[Bikerscum]

Just got a new toy to play with... the Solaredge Site Designer software. Interesting that it recommends either a single 5k inverter, or 2 3k inverters for my system, and a 121% oversizing.