Please help me understand my production rate vs my system size.....???? Confused...

[sharpd1]

Does the production rate decrease slightly when the air temperatures are higher?
Reason i ask is that we have had sunny days in the 50s where my 'current production' rate is stuck on 8.0 on my App for close to 1 or two hours......and then a few days ago, had a fully sunny day where the same rate was going between 7.4 and 7.8....never saw it go past that. temperature was around 85

There didn't seem to be any clouds whatsoever during the hot sunny day i mentioned above...so it made me think about the other factor that seemed to be different: temp.

[ButchDeal]

So, is that a sh*t inverter?

ah no. The SolarEdge inverters are the most efficient in the industry. That is just the previous generation of the SE7600. The current version which came out early last year is the SE7600H and is the HDWave model. I expect SolarCity had a lot of these older inverters sitting around.

[sharpd1]

oh wow, you have an older model SE7600A (not the HDWave version). This makes your readings of 8kW very suspect. It can spit out slightly more than 7.6kw but only for a few seconds and only if the AC voltage is higher. You are not going to get 8kWh in any given hour from it. That said I doubt you are doing all that much clipping here due to the roof layout and shadows.

https://www.solaredge.com/sites/defa...-datasheet.pdf

So, is that a sh*t inverter?

[ButchDeal]

Inverter Model Attached.

oh wow, you have an older model SE7600A (not the HDWave version). This makes your readings of 8kW very suspect. It can spit out slightly more than 7.6kw but only for a few seconds and only if the AC voltage is higher. You are not going to get 8kWh in any given hour from it. That said I doubt you are doing all that much clipping here due to the roof layout and shadows.

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

[sharpd1]

not really something to look at there. Solar is generally done on averages over longer times like day/week/month/ and year.
An hour and peak generation is a really odd one to look at and most of the systems do not work on that.
Now I think what you are getting at is what is the peak kW it can generate at any time but I would suggest that you ignore that as well and look at daily / weekly/ monthly averages.
Your conditions are unlikely to EVERY be constant for an hour ( of course the Earth rotation is the biggest non-constant for your figure but weather and temperature are also).


If you are concerned that your inverter is undersized and clipping then check the model of the inverter before going forward.

You can run the system through PVwatts.nrel and see that such a system could theoretically get to almost 9kWh
But as noted your system is NOT south facing, and is NOT without shadows. Further you are not even sure what inverter you have (though I suspect it is the SE10000h)

Inverter Model Attached.

[ButchDeal]

Let me rephrase my question....perhaps it'll help me understand better.

Given the information i've provided (33 305W pannels and let's say facing directly south, what is the MAXIMUM energy i should be able to produce in 1 HOUR on a sunny day with zero shade?

not really something to look at there. Solar is generally done on averages over longer times like day/week/month/ and year.
An hour and peak generation is a really odd one to look at and most of the systems do not work on that.
Now I think what you are getting at is what is the peak kW it can generate at any time but I would suggest that you ignore that as well and look at daily / weekly/ monthly averages.
Your conditions are unlikely to EVERY be constant for an hour ( of course the Earth rotation is the biggest non-constant for your figure but weather and temperature are also).


If you are concerned that your inverter is undersized and clipping then check the model of the inverter before going forward.

You can run the system through PVwatts.nrel and see that such a system could theoretically get to almost 9kWh
But as noted your system is NOT south facing, and is NOT without shadows. Further you are not even sure what inverter you have (though I suspect it is the SE10000h)

[sharpd1]

Let me rephrase my question....perhaps it'll help me understand better.

Given the information i've provided (33 305W pannels and let's say facing directly south, what is the MAXIMUM energy i should be able to produce in 1 HOUR on a sunny day with zero shade?

[J.P.M.]

Thanks guys. I understand that i would only get 80-90% efficiency...that's why i used the word 'ideal'. i never said i expected it....I was trying to understand it at the 'ideal level'.
With that said, I'm not sure i've gotten a yes or no to this yet....so let me phrase the question again:

under IDEAL (lab/never attainable/whatever we want to call it) conditions, is this correct?

305Wh is the maximum amount of energy that can be produced by one panel in an hour under ideal conditions. 33 x 305Wh equals ~10,000 Wh (ie. 10kW) of energy that can be produced under ideal conditions in an hour.


Also, i'm still trying to understand why the max that i'm showing as producing is 8kW....Why doesn't it show as generating above 8.0kW on the App? is it capped by the inverter? is that normal? Anything I should/can do to make that more?


ps. i generated 55.7 kwhs yesterday super happy and excited!

305 W/panel is the output under S.T.C. conditions.

There are no "ideal" conditions.

Some operating conditions produce more array output than others.

Suit yourself, but you may have an easier time understanding what everyone is telling you if you disabuse yourself of that idea and that term "ideal" with respect to PV.

Under most real operating conditions a 305 W panel will produce less than 305 W. Provided your reporting system is operating nominally as it should, real operating conditions are most likely the reason for the 8.0 kW output you write of.

FWIW, that 8.0 kW for max. power produced and the 55.7 kWh for a daily energy output sounds about right under sunny skies. Reread my post and others for explanations.

Bottom line: At most times and under most operating conditions your array's actual power output will be less than 100% of your array's S.T.C. power output.

On some other (and probably few) occasions or conditions, the 305 W/panel S.T.C. power output may be exceeded. At such times and under such conditions your array's actual power output will be greater than 100 % of your array's S.T.C. power output.

As for increasing output, either power or energy: Besides keeping the array reasonably clean and free of shadows to the greatest extent practical, after design, construction and commissioning, there isn't a whole lot to be done to increase array output. It pretty much is what it is and pretty much at the mercy of the weather and the elements.

[sharpd1]

No Dominion is looking at the DC size. The only reason to put in a smaller one particularly the SE7600 would be that is is the largest that can fit in most panels without major more expensive electrical work. It is the flag ship model with lots of options. Take a look at the inverter and you should see the model number on the side of it.


Well that production curve does not come from the inverter but tesla monitoring and there is a hickup in it were it is showing some production early (the big spike and then valley).

Also looking at the array it is shaddowed. The higher roof with more larger array is going to shadow the lower two sections till the sun gets latter (more west) in the sky,
By that time the sun is lower in the sky and you will have shadows from the trees.

Here's a better report direct from the solarcity app....looks more accurate.....
You're certainly right about everything noted above regarding shadows and trees and etc.

I guess as long as i'm producing close to the estimated 12,000 kwh annually, i shouldn't care if the generation is maxed out at ~8kW at any given moment.....right?

[ButchDeal]

Thank you very much.
Unfortunately, i think i actually do have the 7.6kw version of the inverter. I called Tesla asking this question and that's what i was told. He also told me that it is configured "to produce above the rated kw..." hence the 8kW output.
We have a limit on how much solar we can have here in Northern Virginia....a 10kW system is the max you can have before Dominion energy will start imposing ridiculous penalties....
Could that have something to do with them putting in the 7.6kw inverter?

No Dominion is looking at the DC size. The only reason to put in a smaller one particularly the SE7600 would be that is is the largest that can fit in most panels without major more expensive electrical work. It is the flag ship model with lots of options. Take a look at the inverter and you should see the model number on the side of it.

here is my curve for yesterday. ps. i don't know how/why it shot up to 16kw for a short while....

Well that production curve does not come from the inverter but tesla monitoring and there is a hickup in it were it is showing some production early (the big spike and then valley).

Also looking at the array it is shaddowed. The higher roof with more larger array is going to shadow the lower two sections till the sun gets latter (more west) in the sky,
By that time the sun is lower in the sky and you will have shadows from the trees.

[sharpd1]

Ok so from that information it sounds like your inverter is the newer HDWave version and is the 10kW model so SE10000h Which means that your inverter is capable of spitting out 10kW at any time. BTW the next one down is the SE7600h which is capable of only 7.6kw so you do not have that one.




SolarEdge does not make any 8kW inverter. check for yourself:
https://www.solaredge.com/sites/defa...tasheet-na.pdf


your system is facing SW so you should expect the peak to be after noon, the more west the latter the peak should be.
If you want to post some photos of the graph or give access we can take a look.
production dropping at 6pm would be fairly normal depending on late shadows.

Thank you very much.
Unfortunately, i think i actually do have the 7.6kw version of the inverter. I called Tesla asking this question and that's what i was told. He also told me that it is configured "to produce above the rated kw..." hence the 8kW output.
We have a limit on how much solar we can have here in Northern Virginia....a 10kW system is the max you can have before Dominion energy will start imposing ridiculous penalties....
Could that have something to do with them putting in the 7.6kw inverter?

here is my curve for yesterday. ps. i don't know how/why it shot up to 16kw for a short while....

[ButchDeal]

Inverter is SolarEdge....my representative told me that it's the "best one they have and that it's about 2k extra that he's including for free"....for what it's worth......could have been a complete sales pitch.

Ok so from that information it sounds like your inverter is the newer HDWave version and is the 10kW model so SE10000h Which means that your inverter is capable of spitting out 10kW at any time. BTW the next one down is the SE7600h which is capable of only 7.6kw so you do not have that one.

All modules are facing the same direction, yes. facing south west -ish....
There are no shadows from 10am to 430ish this time of year. i was producing 8kW from 1130ish to 430 yesterday (almost flat line) and then dropped to 5.3kw by 6pm and 0 by 8pm.

just trying to understand why it never goes above "8.0kW output"...

SolarEdge does not make any 8kW inverter. check for yourself:

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

your system is facing SW so you should expect the peak to be after noon, the more west the latter the peak should be.
If you want to post some photos of the graph or give access we can take a look.
production dropping at 6pm would be fairly normal depending on late shadows.

[sharpd1]

No. 305W can be produced (usually +5w,-0w) on that module when it was new, clean, and under STC. STC means a "flash" of light. if it runs for an hour, then the module will heat up and performance will drop. Also that is in DC, If you measure it in AC then you have losses in the longer wires and inverter.

Also "10,000 Wh (ie. 10kW)" these are two different things 10,000 wh = 10kWh NOT 10kW



What inverter do you have?
are the modules all facing the same direction?
are there shadows?

Thank you.

sorry, typo on the 10kW vs the correct 10kwh

Inverter is SolarEdge....my representative told me that it's the "best one they have and that it's about 2k extra that he's including for free"....for what it's worth......could have been a complete sales pitch.
All modules are facing the same direction, yes. facing south west -ish....
There are no shadows from 10am to 430ish this time of year. i was producing 8kW from 1130ish to 430 yesterday (almost flat line) and then dropped to 5.3kw by 6pm and 0 by 8pm.

just trying to understand why it never goes above "8.0kW output"...

[ButchDeal]

Thanks guys. I understand that i would only get 80-90% efficiency...that's why i used the word 'ideal'. i never said i expected it....I was trying to understand it at the 'ideal level'.

It doesn't really work that way . "ideal" doesn't exist. The value you are talking about is STC (Standard Test Conditions) which is a very fast instant flash of light. The PV module does not have time to warm up and heat cuts performance. The light is very bright and most places in the US do not get that level of light any time. Light intensity (insolation) varies considerably with the weather and particulates.
The efficiency of the system also cuts down on production with losses in wires, inverter etc.

under IDEAL (lab/never attainable/whatever we want to call it) conditions, is this correct?

305Wh is the maximum amount of energy that can be produced by one panel in an hour under ideal conditions. 33 x 305Wh equals ~10,000 Wh (ie. 10kW) of energy that can be produced under ideal conditions in an hour.

No. 305W can be produced (usually +5w,-0w) on that module when it was new, clean, and under STC. STC means a "flash" of light. if it runs for an hour, then the module will heat up and performance will drop. Also that is in DC, If you measure it in AC then you have losses in the longer wires and inverter.

Also "10,000 Wh (ie. 10kW)" these are two different things 10,000 wh = 10kWh NOT 10kW

Also, i'm still trying to understand why the max that i'm showing as producing is 8kW....Why doesn't it show as generating above 8.0kW on the App? is it capped by the inverter? is that normal? Anything I should/can do to make that more?

ps. i generated 55.7 kwhs yesterday super happy and excited!

What inverter do you have?
are the modules all facing the same direction?
are there shadows?

[sharpd1]

Thanks guys. I understand that i would only get 80-90% efficiency...that's why i used the word 'ideal'. i never said i expected it....I was trying to understand it at the 'ideal level'.
With that said, I'm not sure i've gotten a yes or no to this yet....so let me phrase the question again:

under IDEAL (lab/never attainable/whatever we want to call it) conditions, is this correct?

305Wh is the maximum amount of energy that can be produced by one panel in an hour under ideal conditions. 33 x 305Wh equals ~10,000 Wh (ie. 10kW) of energy that can be produced under ideal conditions in an hour.

Also, i'm still trying to understand why the max that i'm showing as producing is 8kW....Why doesn't it show as generating above 8.0kW on the App? is it capped by the inverter? is that normal? Anything I should/can do to make that more?


ps. i generated 55.7 kwhs yesterday super happy and excited!