Question about SolarEdge inverter sizing and clipping

[jdonalds]

At this point I don't think my installer is expecting SolarEdge to find anything wrong with the current unit. They are just asking SolarEdge for advice to see if installing a larger unit is called for given the data. I'm hoping SolarEdge will recommend installing a unit with a higher capacity, the installer will do so, and I will be happy. Of course it could go south but I will insist. All of my dealings with my installer have been very good so far.

[JSchnee21]

As Butch said, there is nothing for SolarEdge to do. There's nothing wrong with you 5kW AC inverter. It's performing exactly to spec.

Since you have a 200 amp load side tap, you could potentially upgrade to a larger inverter -- 6kK or 7.6kW (assuming 240VAC). Either by paying your installer the difference OR arm twisting. BUT, check all of your paperwork: 1) installer contract, 2) township permits, 3) architectural engineering plans, 4) power company interconnect agreement. Your options may be limited:

1) Did the installer give you what you contracted for? -- if not, hold their feet to the fire. If so, then it's your dime.
2) If you size up to a larger inverter, you will likely have to redo documents 2, 3, and 4. This may be time consuming an expensive.

While many here will argue that a little clipping is okay, some even say, good. My concern is that if you are clipping that much now, later in the Spring (before it gets too hot) when the sun is higher in the sky, for more hours, and insolation is brighter, you may have some significantly clipping on your hands.

If you download SolarEdge Site Designer

https://www.solaredge.com/us/products/installer-tools/site-designer

You can easily model your array based on your panels, optimizers, and different sized inverters taking into account the orientation and pitch of your roof and your approximate location. While there are other more powerful tools. Site designer is easy to use and covers at least 80-90% of what most folks want to know.

[ButchDeal]

Thanks for the input. I don't completely understand your question but...

Our panel is 200A. The SolarEdge Inverter is wired to a circuit breaker. There is also a separate box with a cut off switch.

We are having some nice weather and daily the graph is clipped at 5,000w when it looks like it could reach to 6,000 if left uninhibited. SolarEdge is hopefully looking at our daily charts and seeing the problem.

SolarEdge will not see a problem other than poor installer. It is within specs just poorly done.
Most installers wouldn't do this unless the array was on multiple azimuths preventing the clipping.
Also I doubt it would reach 6kw, more likely 5.5kw, from the graphs.

[jdonalds]

Would you be able to post pictures or the URL of your public monitoring site (if it has been setup)?

I'm attaching a couple of snaps from my computer.

[jdonalds]

I'm not sure which model inverter you have, as I don't see the -V5 extension on SolarEdge's website. But the max AC power out is not spec'ed to exceed the nameplate rating on the "HD" series. On the old "A" series (which is what I have) the max AC output may be larger than the nameplate on some models (actually every model except the 6000).

But note that the Max AC output is different and unrelated to the DC/AC ratio. While it is common to oversubscribe the panel to inverter ration (aka DC kW in > AC kW out) as often PV array output is much less than panel nameplate ratings (aka 365W in your case per panel). Some will argue the PTC or NOCT values are more representative. It does depend entirely on your location, weather, orientation and inclination.

I assume you have a load side tap? That is to say your inverted is wired in as a breaker in your load center? Do you have a 100amp or 200amp breaker panel? The busbar rating in your breaker panel may be limiting the inverter sizing if you have a load side tap. The other questions is what is your annual electrical consumption? Many power companies limit AC KW sizes based on not exceeding 100% of your historical usage. So this may have also played into the inverter chosen by your installer, OR they just cheaped out.

HD Series Spec's

https://www.solaredge.com/sites/default/files/se-hd-wave-single-phase-inverter-datasheet-na.pdf

A Series Spec's

https://www.solaredge.com/sites/default/files/se-single-phase-us-inverter-datasheet.pdf

The "good" news is that your panel's output will rapidly decay a few to several percent over the next 6 months or so due to LID and soiling. So the frequency of clipping AS IS will reduce itself over time.

But by all means press on your installer to at least upgrade to the 6000HD or better yet the 7600HD if it's on their dime. IMHO, Solar Edge's spec's on the HD series is rather misleading. They significantly increased the permissible DC/AC ratio for the HD vs the A series before you void the warranty. But they actually kept the AC's outputs the same -- or lowered them -- versus the A-series. Seems dumb to me. I expect the solid state electronics in the HD models tolerate less over current DC cresting than the old analog inverters.

The reality is a little clipping is just fine. Sometimes even preferable -- cheaper system cost, better ROI. But as a customer, seeing your potential production fly out the window (even if it is not cost effective to chase those dollars) is admittedly hard to watch.

Thanks for the input. I don't completely understand your question but...

Our panel is 200A. The SolarEdge Inverter is wired to a circuit breaker. There is also a separate box with a cut off switch.

We are having some nice weather and daily the graph is clipped at 5,000w when it looks like it could reach to 6,000 if left uninhibited. SolarEdge is hopefully looking at our daily charts and seeing the problem.

[ButchDeal]

I assume you have a load side tap? That is to say your inverted is wired in as a breaker in your load center? Do you have a 100amp or 200amp breaker panel? The busbar rating in your breaker panel may be limiting the inverter sizing if you have a load side tap. The other questions is what is your annual electrical consumption? Many power companies limit AC KW sizes based on not exceeding 100% of your historical usage. So this may have also played into the inverter chosen by your installer, OR they just cheaped out.


But by all means press on your installer to at least upgrade to the 6000HD or better yet the 7600HD if it's on their dime. IMHO, Solar Edge's spec's on the HD series is rather misleading. They significantly increased the permissible DC/AC ratio for the HD vs the

It is unlikely to be any difference in capacity at the MSP as the difference between the SE5000H and SE6000H is very small and often they both use the same breaker size.

The one thing that would have forced them to use an SE5000H is if the OP has 208V, as the SE5000H supports 208V service bu the SE6000H doesn't

[JSchnee21]

I'm not sure which model inverter you have, as I don't see the -V5 extension on SolarEdge's website. But the max AC power out is not spec'ed to exceed the nameplate rating on the "HD" series. On the old "A" series (which is what I have) the max AC output may be larger than the nameplate on some models (actually every model except the 6000).

But note that the Max AC output is different and unrelated to the DC/AC ratio. While it is common to oversubscribe the panel to inverter ration (aka DC kW in > AC kW out) as often PV array output is much less than panel nameplate ratings (aka 365W in your case per panel). Some will argue the PTC or NOCT values are more representative. It does depend entirely on your location, weather, orientation and inclination.

I assume you have a load side tap? That is to say your inverted is wired in as a breaker in your load center? Do you have a 100amp or 200amp breaker panel? The busbar rating in your breaker panel may be limiting the inverter sizing if you have a load side tap. The other questions is what is your annual electrical consumption? Many power companies limit AC KW sizes based on not exceeding 100% of your historical usage. So this may have also played into the inverter chosen by your installer, OR they just cheaped out.

HD Series Spec's

https://www.solaredge.com/sites/default/files/se-hd-wave-single-phase-inverter-datasheet-na.pdf

A Series Spec's

https://www.solaredge.com/sites/default/files/se-single-phase-us-inverter-datasheet.pdf

The "good" news is that your panel's output will rapidly decay a few to several percent over the next 6 months or so due to LID and soiling. So the frequency of clipping AS IS will reduce itself over time.

But by all means press on your installer to at least upgrade to the 6000HD or better yet the 7600HD if it's on their dime. IMHO, Solar Edge's spec's on the HD series is rather misleading. They significantly increased the permissible DC/AC ratio for the HD vs the A series before you void the warranty. But they actually kept the AC's outputs the same -- or lowered them -- versus the A-series. Seems dumb to me. I expect the solid state electronics in the HD models tolerate less over current DC cresting than the old analog inverters.

The reality is a little clipping is just fine. Sometimes even preferable -- cheaper system cost, better ROI. But as a customer, seeing your potential production fly out the window (even if it is not cost effective to chase those dollars) is admittedly hard to watch.

[macaddict]

My installer has requested SolarEdge take a look at my system. I believe we lost at least 2KWh just today alone. Cool weather and lots of sun created a bell curve with a three hour long flat top today.

Would you be able to post pictures or the URL of your public monitoring site (if it has been setup)?

[jdonalds]

My installer has requested SolarEdge take a look at my system. I believe we lost at least 2KWh just today alone. Cool weather and lots of sun created a bell curve with a three hour long flat top today.

[J.P.M.]

Question: When I'm trying to determine the loss due to summertime high temperatures is that simply ambient temperature? I wouldn't know how to estimate the surface temperature of an almost black panel.

We have many days over 100 degrees F here, sometimes weeks when daytime temperatures are 102 - 112. The sun is intense and there are zero clouds.

Is there any reason to believe that an inverter that is sized the way ours is is somehow more efficient than if I had a higher rated inverter installed? Clipping seems detrimental to me unless there is some sort of efficiency factor that I'm not aware of.

On the panel temps., they will run hotter than the air temp.

Some considerations:

1.)The panels' surface temp. will be higher than the surrounding air.

2.) A dark roof will have surrounding air temps. of maybe 2-4 deg. F warmer than the ground air temp. in summer mid day with a lot of wind, to maybe 6 - 12 F warmer than the ground air on still days.

3.) A VERY ROUGH number for panel cell temp. in deg. C.is : (((POA irradiance)/(32)) + 3) + array area ambient air temp. in deg. C., with POA in W/m^2. The 32 is the very approximate (with some variation depending mostly on wind) heat loss (or gain) coefficient from/to the panel in W/(m^2 deg. C.).

4.) I've measured/calced. that heat loss coefff. for my array several hundred times. The number I got (~ 32 W/m^2 deg. C.) seems to agree fairly well with what a calc of the NOCT temp. usually or commonly works out to be, that is, with a NOCT of, say, 47 C. open circuit NOCT at 25 C. ambient temp. and 1m/sec. wind velocity works out to something like 800 W/m^2/(47-25 + 3) C. = 32 W/(m^2 deg.. C.), with the 3 deg. an approximation of the difference between the array/panel surface temp. and the cell temp. for full sun.

5.) I've also found that acceptable cell temp. approx. can be found from knowing the panel/array STC voltage and the actual, measured voltage and knowing the voltage drop per deg. C from the panel spec sheet. Those results compare favorably enough to measurements to be used as a pretty good check on actual measured temps. Details on request.

[jdonalds]

With solaredge, no same efficiency for the SE5000h as the SE6000H

really little reason to do to do that unless you have a limit on the input side but I would highly doubt you have a service panel that could handle the 5kw but not the 6kw Just pretty much lazy installers that are not familiar with solaredge.

I'm seeing a little bit of loss every day now. We are in a near 100% sun period for a few weeks with highs in the 70s (it's 77 F at noon now). Every day the power graph is like a bell curve, clipped at 5,000 watts for about 2 hours a day. I figure I'm losing about 1kWh per day right now due to clipping. The inverter has now clipped 5 out of the last 8 days and will again today.

On the other hand I can see a potential answer in the numbers. The LG365Q1C-A5 panel datasheet says it has a Maximum Power (Pmax) of 365 watts, but the NOCT Maximum Power is shown as 275 watts. We have 18 panels x 275 watts equals 4950 watts for the whole system. From that I could see how the installers could have chosen a 5000 watt limited inverter. I still don't see the harm in bumping up to the next inverter. Someone said the cost differential isn't much. The panels are obviously capable of outputting over 5000 watts.

I don't know what the roof angle is or the orientation to the south is. Our house isn't exactly facing south but it's not far off.

[ButchDeal]

Is there any reason to believe that an inverter that is sized the way ours is is somehow more efficient than if I had a higher rated inverter installed? Clipping seems detrimental to me unless there is some sort of efficiency factor that I'm not aware of.

With solaredge, no same efficiency for the SE5000H as the SE6000H

really little reason to do that unless you have a limit on the input side but I would highly doubt you have a service panel that could handle the 5kw but not the 6kw Just pretty much lazy installers that are not familiar with solaredge

[ImInPhxAZ]

By those numbers then say you clip equivelant of 2kwh (500w / 4hr) / every 18 days. 365/18, 20.27 days, * 2 = 40kwh a year lost. Peanuts, really. However given the sun is so low this time of year, I guess you will get quite alot more clipping come spring when you still have the cool temps but longer exposure.

Your AC/DC ratio is quite high, curious what azimuth and tilt do you have on the panels? Did they undersize the inverter knowing the panels arent facing true solar south or at enough tilt to get maximum exposure?

[jdonalds]

The good news is that your system will have more clipping in the winter with cold weather. The heat of summer will reduce production.

how many hours is the system clipping now?

It's only happened a few times so far. Just 18 days of operation so far since the system was switched on. Only four hours of clipping total since the system started. We've had clouds and rain. But today was the most as it was the sunniest. Just some high thin clouds. The system clipped from 11:15 am to 12:45 pm continuously. The graph shows a flat line between those times. It looks sort of like a bell curve that's been clipped at 5,000 watts. My "guess" is if it wasn't clipped it might have risen to 5,500 watts. Ambient temperature was 78 degrees F around that time.

Question: When I'm trying to determine the loss due to summertime high temperatures is that simply ambient temperature? I wouldn't know how to estimate the surface temperature of an almost black panel.

We have many days over 100 degrees F here, sometimes weeks when daytime temperatures are 102 - 112. The sun is intense and there are zero clouds.

Is there any reason to believe that an inverter that is sized the way ours is is somehow more efficient than if I had a higher rated inverter installed? Clipping seems detrimental to me unless there is some sort of efficiency factor that I'm not aware of.

[ButchDeal]

The good news is that your system will have more clipping in the winter with cold weather. The heat of summer will reduce production.

how many hours is the system clipping now?