Solaredge inverter sizing?

[Bikerscum]

You haven't yet described the orientation of your panels, very important. The bell curve only
is accurate if all the panels have a southern alignment. Read the paper.

Sorry, all of the panels will be facing south. If it makes any difference, they are 275w Solarworld, 22 of them.

Thanks for your input.

[bcroe]

Ok, I signed a deal today for a 6k system. The guy wrote it up with Solaredge optimizers and a 5k Solaredge inverter, just like the guy I was talking to before. I told him I wanted the 6k inverter and he readily said no problem, no charge, etc. But.... he explained why he chose the 5k. He drew out a bell curve representing power output throughout the day, with the peak in the middle. Then another curve on top of it with wider sides, and a slightly lower peak. The reasoning is that I would clip (maybe) just a touch at peak, but make more in the morning and evening. Something about startup power.

Solaredge actually has a paper on this... inverter_dc_oversizing_guide.pdf and maintains warranty coverage up to 125% oversizing.
The 5k inverter has a max DC input of 6250, a nominal AC output of 5000, maximum 5400.
The one difference between the 5k & 6k is the 5k is max 21A cont. output, the 6k is 25.

Would my 6k system likely hit the 5400 max? I'm starting to lean towards the 5k... the guy really seamed to be knowledgeable on the subject. And I'll need you guys to make me feel good about it.

You haven't yet described the orientation of your panels, very important. The bell curve only
is accurate if all the panels have a southern alignment. Read the paper.

Once the inverter starts, the sides of the curve will be almost identical. My 7.5KW inverters
start at about 125W, so we are taking about a small adjustment of a part of the curve which
itself is less than 2% of the max. The smaller inverter might flatten the top part of the curve.

In my case (Fronius), an inverter is actually multiple inverters. This allows it to start up and
operate efficiently on a lower power level, then switch in more capacity as needed. You might
ask if your inverters do that, and what the start up power is. Bruce Roe

[Bikerscum]

Ok, I signed a deal today for a 6k system. The guy wrote it up with Solaredge optimizers and a 5k Solaredge inverter, just like the guy I was talking to before. I told him I wanted the 6k inverter and he readily said no problem, no charge, etc. But.... he explained why he chose the 5k. He drew out a bell curve representing power output throughout the day, with the peak in the middle. Then another curve on top of it with wider sides, and a slightly lower peak. The reasoning is that I would clip (maybe) just a touch at peak, but make more in the morning and evening. Something about startup power.



Solaredge actually has a paper on this... inverter_dc_oversizing_guide.pdf and maintains warranty coverage up to 125% oversizing.
The 5k inverter has a max DC input of 6250, a nominal AC output of 5000, maximum 5400. The one difference between the 5k & 6k is the 5k is max 21A cont. output, the 6k is 25.

Would my 6k system likely hit the 5400 max?

I can still change my mind on this, and again... the price was a non issue. I'm starting to lean towards the 5k... the guy really seamed to be knowledgeable on the subject. And I'll need you guys to make me feel good about it.

[inetdog]

A 5kW inverter will work, but why not a 6kW. I have a 6kW inverter for my 7.1kW system, it is all about design which make the system work better. The inverter price has drop alot in past years, so getting a 6kW wont hurt.

+1
It is not like the battery powered off grid inverter market where a larger inverter will have a larger constant energy drain whether its output is loaded or not.

[silversaver]

A 5kW inverter will work, but why not a 6kW. I have a 6kW inverter for my 7.1kW system, it is all about design which make the system work better. The inverter price has drop alot in past years, so getting a 6kW wont hurt.

[thejq]

Thanks. I guess the underlying question is how many peak watts can I expect the 6k system to generate?

I hear 80% is a common number?

I'd definitely go with SE6000, considering the price differential is about $30 http://www.wholesalesolar.com/solaredge.html just for reference. This way you don't have to worry about over/under estimate.

[Bikerscum]

Thanks. I guess the underlying question is how many peak watts can I expect the 6k system to generate?

I hear 80% is a common number?

[bcroe]

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?

If your 5K inverter was 96% efficient, it would take 5200W DC input to reach its maximum. If your
panels are not all facing the same direction, or not facing south, you might never hit 5200. Bruce Roe

[Bikerscum]

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.