Question about SolarEdge inverter sizing and clipping

[Kendalf]

New member to the forum, and I'm very interested in the outcome for OP as we're looking at very similar potential solar systems, main difference being that ours is still in the planning stages, and my home is in Southern California. We even drive the same car (Honda Clarity PHEV--I knew that I recognized your username from the Inside EVs forum, Jdonalds!). We're looking at a 6.6kW system with 20 Panasonic 330W panels combined with a Solaredge inverter. I'm trying to determine if our system would be best served with the SE5000H or the SE6000H (the installers that I've received bids from indicate that the price is a wash between both models). From what I've been seeing in this thread, it sure seems like I should select the 6kW inverter, which would give me a 1.1 ratio.

My question is, when a system is oversized with a higher DC/AC ratio, does this generate more excess heat in the inverter? I believe I read somewhere that any input energy beyond the rated power output capability of the inverter needs to be dissipated somehow, and it seems that a lot of it would be dissipated as heat. The HD-Wave line of inverters does not have active cooling fans, only natural convection, so the less heat that is generated within the inverter, the better, it seems to me.

I'm going to try running that hourly PVWatts analysis that J.P.M. suggested. Is 10% system loses a more realistic estimate nowadays? The default in PVWatts is 14% and that's what I've been using to run the annual production estimates.

[ButchDeal]

New member to the forum, and I'm very interested in the outcome for OP as we're looking at very similar potential solar systems, main difference being that ours is still in the planning stages, and my home is in Southern California. We even drive the same car (Honda Clarity PHEV--I knew that I recognized your username from the Inside EVs forum, Jdonalds!). We're looking at a 6.6kW system with 20 Panasonic 330W panels combined with a Solaredge inverter. I'm trying to determine if our system would be best served with the SE5000H or the SE6000H (the installers that I've received bids from indicate that the price is a wash between both models). From what I've been seeing in this thread, it sure seems like I should select the 6kW inverter, which would give me a 1.1 ratio.

My question is, when a system is oversized with a higher DC/AC ratio, does this generate more excess heat in the inverter? I believe I read somewhere that any input energy beyond the rated power output capability of the inverter needs to be dissipated somehow, and it seems that a lot of it would be dissipated as heat. The HD-Wave line of inverters does not have active cooling fans, only natural convection, so the less heat that is generated within the inverter, the better, it seems to me.

I'm going to try running that hourly PVWatts analysis that J.P.M. suggested. Is 10% system loses a more realistic estimate nowadays? The default in PVWatts is 14% and that's what I've been using to run the annual production estimates.

There is no (zero) reason to go with the smaller inverter for you. SolarEdge does not have the same issues for undersizing as string inverters.
If it is undersized there is no need to dissipate the energy at the inverter it is just not generated so stays at the solar module not inverter.

[J.P.M.]

I did buy Solar for Dummies. That book is now out of date and needs a rewrite. It is full of duplicate information too. I gained very little from the book. I may be underselling myself calling myself a novice. I do have a 40+ year background in hi tech electronics. It's just that I haven't studied all the in's and out's of solar systems.

I still don't see any of my data on PVOutput. isn't it supposed to automatically pull data from my system?

Everyone's red is different. From what and how you write about solar energy and PV, it's somewhat obvious to me that you indeed gained very little from the book. I agree the book may need some updating, and I don't agree with everything in it, but most of the info in there is pretty basic and correct and therefore would seem (to me only) relatively time independent with respect to relevance.

A background in high tech electronics is nice, and worthy of respect, but it's of limited help when it come to the basics of things like resource assessment, solar geometry, use reduction and other things, not to mention, for whatever it's worth, economics. Solar is more about understanding the energy inputs and outputs, and where the come from and where they go than it is about simply counting electrons and potential differences.

When referencing quickly changing technology no printed source stays current for long. The book is a good source for those basic concepts and other matters. FWIW (but probably not much), learning about resource availability can help you discover that Redding, while quite sunny, is not the 2d or 3d sunniest place in the U.S. by any reasonable measure. Far from it.

Good luck.

[J.P.M.]

New member to the forum, and I'm very interested in the outcome for OP as we're looking at very similar potential solar systems, main difference being that ours is still in the planning stages, and my home is in Southern California. We even drive the same car (Honda Clarity PHEV--I knew that I recognized your username from the Inside EVs forum, Jdonalds!). We're looking at a 6.6kW system with 20 Panasonic 330W panels combined with a Solaredge inverter. I'm trying to determine if our system would be best served with the SE5000H or the SE6000H (the installers that I've received bids from indicate that the price is a wash between both models). From what I've been seeing in this thread, it sure seems like I should select the 6kW inverter, which would give me a 1.1 ratio.

My question is, when a system is oversized with a higher DC/AC ratio, does this generate more excess heat in the inverter? I believe I read somewhere that any input energy beyond the rated power output capability of the inverter needs to be dissipated somehow, and it seems that a lot of it would be dissipated as heat. The HD-Wave line of inverters does not have active cooling fans, only natural convection, so the less heat that is generated within the inverter, the better, it seems to me.

I'm going to try running that hourly PVWatts analysis that J.P.M. suggested. Is 10% system loses a more realistic estimate nowadays? The default in PVWatts is 14% and that's what I've been using to run the annual production estimates.

To your question about heat generation: Unless conservation of energy and the consequences of entropy have been violated, the electricity that does not get to or is not used by the inverter(s) and is not dissipated within the inverter(s) is converted to (additional) heat, mostly within the array, raising it's temp. above what it would be if all the generated electricity were used by the inverter(s). Any energy of any form that does not make it from the array to the inverter for whatever reason will be dissipated as heat, either by the wiring on the way to the inverter(s) or, most likely and mostly by the array. That electricity will increase the array temp. above what it would otherwise be if all the electrical output of the array were to be used by the inverter(s). That increased temp. will decrease array efficiency.

As for PVWatts system loss parameter: That is a number that combines several points of system loss. See the PVWatts help/info screens. Shading and system availability alone each make up 3 % of that 14 %. If there is no shade and the system is on, the system loss parameter will be (or can be treated as) 14 - 3 - 3 = 8 %. Keep in mind that PVWatts is for system design and the results are best or most accurate for long term (many years) annual output.

10 % is, IMO a more realistic number, but if you're going to take the time to do as you write, I'd suggest you consider using the more detailed input for system losses by clicking on the info button and then the calculator button next to the system loss parameter on the PVWatts input screen.

The 14% is also what a lot of peddlers use as one of many stealth sales tool to B.S. customers into oversizing a system. Think like a peddler. They make money putting systems on property, not saving users money. No one ever got fired for oversizing. A little oversize is prudent. Stacking up fudge factors is unethical. Caveat Emptor.

Many users who have taken the time have found that using 10 % as a system loss parameter seems to produce modeled output that is closer to what their system actually produces. But, due to the nature of the resource, the lack of monitoring equipment and knowledge about what's being measured, reliable quantitative data that's more than anecdotal is pretty scarce.

With that said, many users incorrectly think PVWatts and other solar generation models are predictors of output on a daily basis. They are not.To the extent that the weather (including irradiance) for any particular short time period matches the weather PVWatts or other models use, they can produce output that pretty much matches what a correctly modeled system produces. But if, for example, PVWatts uses a cold, cloudy day's weather and the actual weather that day is bright and cloudless, the modeled and actual output will not be the same. Using longer periods (say, a month) tends to smooth things out a bit, but because short term weather is more chaotic than long term climate PVWatts, or any solar system model is more accurate as the time period under consideration gets longer. See the PVWatts help screens. There, it's stated that actual system monthly output to model monthly output le can be off as much as +/- 30 %, or maybe +/- 10 % when the time period is annual.

An example, FWIW: Using running 31 day actual output for my system against a running 31 day PVWatts modeled output with the system loss parameter adjusted to 8.2 % so that PVWatts annual output matches that of SAM, after ~ 1,560 running 31 periods, the actual to modelled output ratio for those 31 day periods is 0.994 with a std. dev. is 0.099. that would mean that if my data is valid, at the 99% confidence level, the variation in my output for any prior 31 day period was something like +/- 23 to 25% or so of what PVWatts modeled for my system output using a system loss parameter of 8.2 %.

- However, that does not mean that the next 31 days' output, or any 31 day period's output will be within, say +/- 25% of the average. Chances are it will, but climate's what you expect and weather's what you get.

PVWatts can be bastardized to produce a daily or even hourly output, but caution is advised, mostly due the actual weather being different than what the model uses.

For my situation, SAM from NREL, which might be best described as PVWatts on steroids, produces modeled output that's about 5-6 % greater than what PVWatts produces. Another model, TRNSYS output is about the same as SAM. My money's on most of that difference being due to the system availability and shading as mentioned above.

[Kendalf]

I ran some analysis in PVWatts using a 10% system loss parameter and the results were helpful. For one, it suggests that one of the companies bidding for our business is severely underestimating the potential production of a 6.6 kW system at our location (he calculated 9900 kWh vs PVWatts estimate of just over 12,000 kWh AC system output). Since this company is offering a production guarantee, I can understand why they want to underestimate and overproduce.

I looked at the hourly results as well and it looks like over the course of a year the system would clip an estimated 757 total hours if I used a 5kW inverter, for a total of 271 kWh lost due to clipping. I basically summed up the data points where the DC Array Output exceeded 5000 W. If that's not the right way to look at the data, please correct me!

But it sure seems like a clear sign to go with the 6kW inverter.

[J.P.M.]

I ran some analysis in PVWatts using a 10% system loss parameter and the results were helpful. For one, it suggests that one of the companies bidding for our business is severely underestimating the potential production of a 6.6 kW system at our location (he calculated 9900 kWh vs PVWatts estimate of just over 12,000 kWh AC system output). Since this company is offering a production guarantee, I can understand why they want to underestimate and overproduce.

I looked at the hourly results as well and it looks like over the course of a year the system would clip an estimated 757 total hours if I used a 5kW inverter, for a total of 271 kWh lost due to clipping. I basically summed up the data points where the DC Array Output exceeded 5000 W. If that's not the right way to look at the data, please correct me!

But it sure seems like a clear sign to go with the 6kW inverter.

FWIW, that 12,000 kWh may seem like a lot for a 6.6 kW system (12/6.6 = 1.82 kWh/STC kW), but possible. SAM has my system (zip 92026, az. 195.75 deg., tilt 18.75 deg.) at about 1.81 kWh/STC kW unshaded, and production seems to confirm that's possible (with the 4+yr.,365 day actual output after ~ 5 % late afternoon shade loss off the total at 9,010 kWh/yr. or ~ 1.72 kWh/yr. per STC kW on a 5.232 kW system). Given the short time frame of 4+ years and the weather variability, reality is a lot closer to models' estimates than I'd have thought.

You and I won't do that well every year, and that annual total will also decrease with time as the system deteriorates, but unless you have a way off south system orientation, or a boatload of shade, or the system size is different (smaller) than 6.6 kW, whoever told you ~ 9,900 kWh/yr. is dancing with your leg.

Not knowing anything else about your application, I'd probably also go w/ a 6 kW inveter, but I'd look at other stuff besides Panasonic - good stuff but maybe overpriced. Above and beyond some basic quality level, panels are pretty much a commodity. They're an appliance - not a lifestyle.

BTW, all production guarantees are useful as marketing/sales tools but otherwise useless B.S. Read the fine print and tell me how claim verification is even possible much less likely.

Now, let's you & me get out of so-cal=burbs thread.

[jdonalds]

When referencing quickly changing technology no printed source stays current for long. The book is a good source for those basic concepts and other matters. FWIW (but probably not much), learning about resource availability can help you discover that Redding, while quite sunny, is not the 2d or 3d sunniest place in the U.S. by any reasonable measure. Far from it.

Good luck.

J.P.M. you got me thinking when you suggested Redding isn't the second sunniest city in the country. I realized it was just something I'd heard around town. I thought it was worth a look for my self. What I found was various sites with lists of the sunniest cities. Redding was second on some lists, but absent from other lists. What I saw was some of the lists are filtered for cities over 100,000 population, or 1,000,000 population. Redding is only 90,000 populatioin. Then I went to the source NOAA and found this. https://www1.ncdc.noaa.gov/pub/data/...pctposrank.txt which does list Redding CA in second place after Yuma AZ.

So it turns out to be true.

The upgrade of my system is moving along pending lead times, design changes, and city permits. I've decided to upgrade to the 7600 model of SolarEdge so I should have margin and won't have clipping. I'm adding two more panels as well. The system was sized for the house but we've added the car with it's 17kW battery.

[J.P.M.]

J.P.M. you got me thinking when you suggested Redding isn't the second sunniest city in the country. I realized it was just something I'd heard around town. I thought it was worth a look for my self. What I found was various sites with lists of the sunniest cities. Redding was second on some lists, but absent from other lists. What I saw was some of the lists are filtered for cities over 100,000 population, or 1,000,000 population. Redding is only 90,000 populatioin. Then I went to the source NOAA and found this. https://www1.ncdc.noaa.gov/pub/data/...pctposrank.txt which does list Redding CA in second place after Yuma AZ.

So it turns out to be true.

The upgrade of my system is moving along pending lead times, design changes, and city permits. I've decided to upgrade to the 7600 model of SolarEdge so I should have margin and won't have clipping. I'm adding two more panels as well. The system was sized for the house but we've added the car with it's 17kW battery.

I won't try to dispute the numbers in the table you show. But, it is an example of how things get confused by definitions and other things. Statistics don't lie, statisticians do - that type of thing.

Let's start with how long that table says the Redding claim is based on. Looks like 10 years. Not a long time considering 30 years is what is commonly considered necessary to make inferences.

Next, know that % of possible sunshine, while it's an easy number to get your brain around, is better used for planning outdoor activities than solar design, starting with the question of just what constitutes "sunshine". As in the question: Just what constitutes a "sunny" condition" ? How bright ? About 300 W/m^2 irradiance will cast a shadow, but that's a long way from a mid day direct reading of around 1,000 W/m^2. So, does that 300 W/m^2 condition count as part of the % of sunshine or just a "sunny" condition ? Also, even in VERY clear and mostly cloudless locations, about 20 % of the solar radiation received is not direct irradiance, but diffuse, that is, sunlight received after being scattered and filtered by the atmosphere. Any clouds will only serve to increase that percentage.

NOAA and NREL provide % sunshine estimates for info and it has some uses, but to use such records for solar design purposes to claim how sunny a place might be is a misuse of the data and misleading. It's also pretty useless except in some qualitative sense.

Next, one quantitative way of several the solar resource is estimated by knowledgeable folks is to use something called the "clearness index". It's the ratio of how much insolation is received at a location on a horizontal surface compared to how much radiation is received at that same lat. and long. but above the earth's atmosphere. Redding, while sunny, is not # 2 % in that category. The clearness index for the Redding airport using TMY data is about 0.60. That's a nice number. but, that number is exceeded by many places. Inland San Diego is 0.62. Phoenix is 0.67. Most every place in AZ is > 0.65. Albuquerque is 0.65. Most of NM is > 0.65. Pueblo is 0.62. Much of CO is >0.60.

Many locations south of San Francisco and west of, say, Denver have a clearness index greater than that of Redding, that is, > 0.60. Redding is sunny, but it's not the 2d sunniest place in the U.S. as estimated by the methods used by solar energy researchers. Use the TMY databases to get an estimate of annual terrestrial GHI to extraterrestrial irradiance in the same plane. You'll find many locations with clearness indices >0.60.

By way of confirmation of the clearness index data, I just ran PVWatts for a few locations, using a 1kW array, facing south and tilted at local latitude.

Redding: 1,378 kWh/yr.

San Diego: 1,784 kWh/yr.
Phoenix: 1,874 kWh/yr.

Chicago: 1,353 kWh/yr.
Boston, MA: 1,421 kWh/yr.

Even Buffalo, NY will produce 1,237 kWh/yr. - not as much as Redding, but maybe not too far off. Make the Buffalo array 10% bigger and arrays in the two locations will probably produce similar average annual output over time.

[Guest]

My question is, when a system is oversized with a higher DC/AC ratio, does this generate more excess heat in the inverter? I believe I read somewhere that any input energy beyond the rated power output capability of the inverter needs to be dissipated somehow, and it seems that a lot of it would be dissipated as heat. The HD-Wave line of inverters does not have active cooling fans, only natural convection, so the less heat that is generated within the inverter, the better, it seems to me.

hello all. I'm new to this forum as well not an expert, but I'd like to respond to this question based on my physics studies.

It's a common mistake to believe that power is pushed by the source (pv panel, battery, grid etc). Instead you should think as that power is pulled by the consuming device. It's easy to accept this if you look at a wall outlet: it's capable of outputting 3kW and driving a vacuum cleaner or washing machine, but if you connect a 5W led night lamp it won't dissipate the remaining 2.995kW as heat. It simply won't draw more than 5 watts, and that can all go backwards the whole grid if there's no other consumer. Theoretically you could connect your 5 watt night light as the only consumer directly to a 40GW nuclear plant, but in reality you'll have some issues

So in a pv system when the inverter is clipping it's not somehow "blocking the incoming power to enter the grid" but it's simply not pulling more than the limited power even if the consumer would draw more.

The heat you're seeing produced by your inverter is the loss due to inefficiencies by the device. It should be proportional to the power passing through the inverter and not by the power "trying to enter" it. If you run your inverter for long time at it's clipping point then it will heat up because it's running at it's maximum designed performance, but it should be handled by the device as long as other circumstances (ambient temperature, air flow, etc) are met.

When looking from the energy balance side it is true that the energy irradiated from the sun by the panel must go somewhere when there's no or not enough power drawn from the panels. And yes mostly this is heat - but is it really a problem? Just think about: do your pv panels blow up when the inverter is not turned on during daylight?

Obviously no and the answer lies with the efficiency of the panels. Usually these are still pretty low, for cheap panels around 15%, and even high end panels just around 20%. It means that when a 6kW array can output it's maximum power with 15% efficiency 85% of the sun power is heating the panels. If you clip that 6kW to 4kW what happens is you leave 2/3rd of that 15% "in the panel", so the panel will be heated by 90% of the irradiated power instead of 85%. That's less than 6% increase in heat, so if your panel normally heats up by 30C compared to ambient temperature, now it may heat up by 31.7C. In practice there are also other components heating the panel (junctions, cables, etc) which in turn heats up proportional to the current flowing through them, and when clipping happens they won't reach they can run cooler as opposed to full load. This could lead to even less noticable change in the panel heat.

And it's true, that this extra heat might decreases performance of the panels, but possibly not below the required power and eventually there will be a balance in the system.

[Kendalf]

The upgrade of my system is moving along pending lead times, design changes, and city permits. I've decided to upgrade to the 7600 model of SolarEdge so I should have margin and won't have clipping. I'm adding two more panels as well. The system was sized for the house but we've added the car with it's 17kW battery.

jdonalds, any update on your system upgrade? I wrote about how my installer just tried to shortchange me with a SE5000H inverter when I had requested an SE6000H model in this post:

https://www.solarpaneltalk.com/forum/solar-panels-for-home/solar-panels-for-your-home/373226-need-some-guidance-to-the-proper-size-selection-of-the-inverter-for-my-system?p=374845#post374845

Thankfully I was able to get the company to switch back to the 6kW inverter before we signed off on a completed install.

[imola.zhp]

Can someone show what clipping looks like on Solar Edge's portal? My system is 10.33kW, my inverter is an 8.6kW, which I am just learning is out of the range of a 1.1 ratio. I never see anything above 8.0 on the solar edge portal which sufficed me for a month (give or take) but it does seem to get flat at about 7.8/7.9 making me think perhaps clipping is going on, just lower than the inverters rating. Thanks in advance.

[JSchnee21]

Welcome imola.zhp!

Is this a US residential install? How long ago? There is no model 8.6kW in the US. Just 6.0kW, 7.6kW, 10.0kW, 11.4kW. Additionally, within the 7.6kW there is the "A-series" (older clips at ~8kW -- 8350W) and the newer "HD" series which clips at ~7.6kW (7600W).

Given the ~8.0kW peak you describe, it sounds like you have a 7600A which would indeed clip at ~8kW, though it could be a 7600H depending on how things are being rounded. The portal should have the model number. If not, you can compare a picture of your inverter to those on the SE website. The "HD" is much smaller than the "A" series.

If you picture in inverted parabola, Poisson distribution, (or a smoothly curved mountain) -- these would have a nicely rounded peaks at the top (given no clouds, shade, etc.). Instead, with clipping, from approx ~11am to 1pm (depending on peak solar noon in your location) the mountain top will be cut squarely off. That is to say, you will see a horizontal straight line output (at roughly 8kW) from the beginning of clipping until the end (save for a passing cloud or two). This will occur across multiple days -- assuming the weather is similar on each of those days.

The maximum permissible DC STC (per SE warranty) on the 7600A is 10,250W. On the 7600H is it 11,800W. But from a best practices perspective, unless you have a lot of shade or multiple non-South orientations, using a 10.33/7.6 = 1.36x panel to inverter ratio is rather high. Like I said it would potentially void the warranty for the A-series. But Butch or others can give more specific details.

All the specs are on SE's product PDF's. If you search for "Solar Edge 7600 PDF" the specs will come right up.

What state are located in? How many panels, what pitch and orientation?

Also note, there are legitimate reasons which may require under-sizing the inverter. Depending on whether you have a line side or load side inverter tie in, the size of your electrical panels bus bars, etc. Sometimes planning for a little clipping can be more cost effective than over-sizing the inverter and using a line side tap. Also, some jurisdictions don't permit line side taps.

Is this a new install? Do you know/trust the installer?

-Jonathan

[imola.zhp]

Welcome imola.zhp!

Is this a US residential install? How long ago? There is no model 8.6kW in the US. Just 6.0kW, 7.6kW, 10.0kW, 11.4kW. Additionally, within the 7.6kW there is the "A-series" (older clips at ~8kW -- 8350W) and the newer "HD" series which clips at ~7.6kW (7600W).

Given the ~8.0kW peak you describe, it sounds like you have a 7600A which would indeed clip at ~8kW, though it could be a 7600H depending on how things are being rounded. The portal should have the model number. If not, you can compare a picture of your inverter to those on the SE website. The "HD" is much smaller than the "A" series.

If you picture in inverted parabola, Poisson distribution, (or a smoothly curved mountain) -- these would have a nicely rounded peaks at the top (given no clouds, shade, etc.). Instead, with clipping, from approx ~11am to 1pm (depending on peak solar noon in your location) the mountain top will be cut squarely off. That is to say, you will see a horizontal straight line output (at roughly 8kW) from the beginning of clipping until the end (save for a passing cloud or two). This will occur across multiple days -- assuming the weather is similar on each of those days.

The maximum permissible DC STC (per SE warranty) on the 7600A is 10,250W. On the 7600H is it 11,800W. But from a best practices perspective, unless you have a lot of shade or multiple non-South orientations, using a 10.33/7.6 = 1.36x panel to inverter ratio is rather high. Like I said it would potentially void the warranty for the A-series. But Butch or others can give more specific details.

All the specs are on SE's product PDF's. If you search for "Solar Edge 7600 PDF" the specs will come right up.

What state are located in? How many panels, what pitch and orientation?

Also note, there are legitimate reasons which may require under-sizing the inverter. Depending on whether you have a line side or load side inverter tie in, the size of your electrical panels bus bars, etc. Sometimes planning for a little clipping can be more cost effective than over-sizing the inverter and using a line side tap. Also, some jurisdictions don't permit line side taps.

Is this a new install? Do you know/trust the installer?

-Jonathan

Jonathan,

Thank you for your detailed response.

This is a US residential installation in Memphis, TN, 35 295w Canadian Solar panels in portrait orientation. 29 panels on the main portion of the roof at a 12/12 pitch and 6 panels on the garage roof with a 10/12 pitch. The house is in the middle of a curve where a north/south street turns into an east/west street so the orientation is slightly SSW, it makes most of its power in the afternoons. There is some shading in the late afternoon from a neighboring house. It was installed this summer but with many many delays, it has only been on for a little over a month now.

My apologies, in the menu of the inverter it states a max of 8.4, however it is a 7600A and wow, I'm trying not to be upset that the installer undersized the inverter so much. I'm still not sure it is clipping but it sure seems like it is, my peaks are frequently flat at the top. I asked him about the unit being undersized shortly after installation when I found the 8.4kW "MAX" in the menu; but the installer said the inverter was paired correctly. I also asked for a wifi unit and he installed a cellular T-Mobile unit that updates whenever it feels like it, annoying.

I thought I trusted the installer, he installed another system in my HOA and the homeowners have been very happy with it. I am very happy with the install, but the charts look as if some clipping is happening. Is there a large price difference between what I have, 7600A, and the next size up? I can't understand why we went all the way to 10.325 if the inverter can't handle all of that incoming power. It seems as though we should have installed fewer panels or a larger inverter.

[foo1bar]

My system is 10.33kW, my inverter is an 8.6kW, which I am just learning is out of the range of a 1.1 ratio. I never see anything above 8.0 on the solar edge portal which sufficed me for a month (give or take) but it does seem to get flat at about 7.8/7.9 making me think perhaps clipping is going on, just lower than the inverters rating.

If it's clipping, what I've seen by other people is that it'll be very flat for that plateau.

I have 8.96kW of panels on 7.6kW inverter and I haven't seen clipping. (well, I have seen that I think it hit it's max for a very brief time when I had sun poking through clouds - so "clipping" for less than 15 min)
My graphs look somewhat flat at the top due to multiple orientations (some panels east-ish some pointing westish - so it winds up more flattened at the top then a simple all-in-one-direction system.
But when you look closely at the graph you can see that there is some variation over that peak hour - not a lot but some.

As Jonathan asked - are you sure it's a 8.6kW inverter?
(A quick search shows that might be true if you're in Mexico, have WYE service, and have a SE10K model. And there might be other situations besides that.)

7.6kW inverters are common in the US - so if you're in the US maybe you thought it was 8.6, but it's really 7.6.

[foo1bar]

I can't understand why we went all the way to 10.325 if the inverter can't handle all of that incoming power. It seems as though we should have installed fewer panels or a larger inverter.

Larger than 7600W inverter means you need a >40A breaker for it.
And that can result in having to spend significantly more for a new panel or other changes to handle it.

With clipping, keep in mind that during the 1-2 hours you have clipping you're probably still getting vast majority of what you would have if it wasn't clipping. It's a bell curve, so be careful making a guesstimate on how much is above the clipping line.
Clipping a few percent during the peak can be a better choice financially than going with fewer panels (less production) or a larger inverter (more expense).

As an example, if I have a 10kW inverter, and my panels will hit 10.5kW for a few minutes each day during peak production, that means I'm missing out on 5% during those few minutes (and 2-3% over the ~1 hour of clipping).
But I have the other 10 hours of the day where I'm getting 5% more production. So I may have 1 hour maxed out at 10kW, but I have 5 hours on each side at zero-to-10kW, and those parts are 5% more than if I weren't clipping. So I miss out on less than 0.5kWH because I didn't have a bigger inverter. But I gained 4kWH (on a ~80kWH day for this hypothetical) because I had more production than if I had downsized the panels to not have clipping.

OTOH, if you're clipping this month and you're in TN, it may be that you're past the point where it made sense to add that last panel or two.
The "good" news is that panels degrade a little each year - so you will have less clipping over time.

If you can upgrade to a larger inverter without a major issue (ex. main panel upgrade) then I'd probably try to convince the installer that he should have used a larger inverter.