SunPower SPR-E20-327-C-AC Power Testing

[ajonestx]

Another option for you is to go onto the sunpower website and look at daily power (not energy) output - that is in 5 minute increments (you can also export the data). Assuming none of your panels are shaded, you should have an increment at some point close to your STC (320 watts * number of panels). I would start by looking at a month when you have peak production

For example, on 5/11 at 11:42 AM, it shows I was producing 8.3 kW. Dividing that by my 26 panels show 319.2 watt per panel.
On 9/25 @ 12:05, produced 8.25 kW (317 watt per panel)

You will see that you rarely produce at peak for very long, but as long at you are seeing it occasionally, it should indicate all is well. For 9/25, the next highest was @ 12:10, but had dropped to 7.88. There were only about 5 periods on that day were I was above 270 watts. So if you are randomly pulling them, very good chance you will miss the peak, especially if you are pulling them in November vs spring or fall.

yea... done that. highest that I have seen in three years is 4.6 (divide by 18 and you get 255 watts). Prior to the microinverter swap, the highest I saw was 5.41 (divide by 18 and you get 300 watts). Keep the ideas coming! Bummer though... with the new MySunPower app, the 5 minute system power data goes away. I have shade in November (until we have one of our trees removed in January), so I will not be able to really test this option until April / May 2022. I just wish I could see a peak output once, but have not since the MI swap in 2018. When was your system installed?

[ajzwilli]

Another option for you is to go onto the sunpower website and look at daily power (not energy) output - that is in 5 minute increments (you can also export the data). Assuming none of your panels are shaded, you should have an increment at some point close to your STC (320 watts * number of panels). I would start by looking at a month when you have peak production

For example, on 5/11 at 11:42 AM, it shows I was producing 8.3 kW. Dividing that by my 26 panels show 319.2 watt per panel.
On 9/25 @ 12:05, produced 8.25 kW (317 watt per panel)

You will see that you rarely produce at peak for very long, but as long at you are seeing it occasionally, it should indicate all is well. For 9/25, the next highest was @ 12:10, but had dropped to 7.88. There were only about 5 periods on that day were I was above 270 watts. So if you are randomly pulling them, very good chance you will miss the peak, especially if you are pulling them in November vs spring or fall.

[ajzwilli]

I know the consumer access to the site in the second screenshot has been removed, but installers still have access to the data, I've received a screenshot output from my installer this year showing the peak day/month/year/all-time data from the SunPower partner site - but they don't like to share it, so I only ask for 1x a year. The first screenshot does not have historical data, it is only point in time

I'm open to a private convo, but not able to do it via this forum as they don't have that feature.

All of my micro's (AC) have maxed out at either 322 or 323 watts this year. Last time they exceeded STC (320) was in Sept/Oct. For November, highest I had was 284 / 320 (88%), but that was only for 1 day (Nov 3), the rest of my observations for November were at or below 270, which sounds like what you saw. Note, for November I had about 50,000 observations across my 26 panels (1,890/panel = 60 observations / panel / day) and only 0.3% observations were above 270.

[ajonestx]

That may or may not be true in general over the long run on average, (not even sure how one would calculate such a figure), but the OP was indicating they have seen a 10% decrease since the new micros were installed and is trying to isolate the issue. I assume he is referring to peak production, not average production, but I could be mistaken as we have not yet seen the screenshots OP mentioned. In the spring and fall with cooler temps, I still see up 101% of STC for several intervals in a given month at the AC / micro level (323 watts out of 320 STC) and up to 102% of STC at the DC/panel level (334 out of 327 STC). I do have 2 out of 26 panels that have peaked at 326 watts (DC) and 1 panel that has hit STC at 327 watts (DC), the remaining have hit anywhere from 328 to 334 watts (DC).

You mentioned "up to 101% of STC" for max AC module power. What range of AC power levels are you seeing at the micro level? Are all of them maxing out at around 323?

[ajonestx]

Thanks, so are those the only two reference points you have? If so, then I don't think you have anything to worry about and I would have your installer pull peak production (day/month/year/lifetime). If you are not able to get peak production, then you can pull the data from the first screenshot your self, but you will likely want to wait until spring when the sun is higher and you are producing more on a given day.

I no longer have access to the second screen shot program - the manufacture took it off line. are you suggesting that the first screen shot program has historical data? My 3rd installer says they do not have access to peak power data - only live data. I do have other reference points in November, but they are much lower. After eight months of trying, the manufacture refuses to send peak power broken down by day/month/year/lifetime. they did send me one spreadsheet that shows peak for the lifetime and confirms that the max power produced by module is about 270 watts. They also say everything is working as expected. Agreed, March and April are going to be the best time to check live numbers. I am stuck without data. Can I talk to you privately about the data access you have access to?

[ajzwilli]

Thanks, so are those the only two reference points you have? If so, then I don't think you have anything to worry about and I would have your installer pull peak production (day/month/year/lifetime). If you are not able to get peak production, then you can pull the data from the first screenshot your self, but you will likely want to wait until spring when the sun is higher and you are producing more on a given day.

[ajonestx]

That may or may not be true in general over the long run on average, (not even sure how one would calculate such a figure), but the OP was indicating they have seen a 10% decrease since the new micros were installed and is trying to isolate the issue. I assume he is referring to peak production, not average production, but I could be mistaken as we have not yet seen the screenshots OP mentioned. In the spring and fall with cooler temps, I still see up 101% of STC for several intervals in a given month at the AC / micro level (323 watts out of 320 STC) and up to 102% of STC at the DC/panel level (334 out of 327 STC). I do have 2 out of 26 panels that have peaked at 326 watts (DC) and 1 panel that has hit STC at 327 watts (DC), the remaining have hit anywhere from 328 to 334 watts (DC).

correct. I am trying to isolate peak power (kW) per module. NOT peak production (kWh) nor average production (kWh).

[ajonestx]

February 2017 with most panels above 300 watts. Isolated date again / not a range.

[ajonestx]

How much data do you have from those screenshots, can you share them here? It's a specific day, or a period of time? If you are only getting specific dates, then that is likely the issue. There is a screen that shows peak power generation for current day/month/year and lifetime by panel. My installer has provided it to me a couple times upon request after consumers lost access to the SunPower site where you could see panel level detail.
The reason I ask is that I have over a years worth of 5 minute interval panel level data and over half the days, my peak production at any interval for a given day is 78% or less of the 320w(I have same panel as you, except 327-e series). So depending on what time periods you are seeing in your snapshots (ie. specific days versus YTD), 78% (270 of 320watts) is plausible. I will note the lowest peak production for any interval in any month was Nov at 89% (both this year and last year). I only had six days in November where at least some interval during the day peak production was at or about 78%. For December peak production for any day is currently sitting at 88%. Excluding Nov 2020, Nov and Dec 2021, I have at least one interval in a the rest of the months where I am at 99% of the 320 watts.

April 2021 with most panels about 270. I do not know how to access date ranges. Getting an error trying to post a second photo with 2017 data, so will do in a separate post.

[ajzwilli]

Panels generally, produce only 80% of their Lab ratings. ( that's real close to the above mentioned 78%)

That may or may not be true in general over the long run on average, (not even sure how one would calculate such a figure), but the OP was indicating they have seen a 10% decrease since the new micros were installed and is trying to isolate the issue. I assume he is referring to peak production, not average production, but I could be mistaken as we have not yet seen the screenshots OP mentioned. In the spring and fall with cooler temps, I still see up 101% of STC for several intervals in a given month at the AC / micro level (323 watts out of 320 STC) and up to 102% of STC at the DC/panel level (334 out of 327 STC). I do have 2 out of 26 panels that have peaked at 326 watts (DC) and 1 panel that has hit STC at 327 watts (DC), the remaining have hit anywhere from 328 to 334 watts (DC).

[Mike90250]

Panels generally, produce only 80% of their Lab ratings. ( that's real close to the above mentioned 78%)

[ajzwilli]

How much data do you have from those screenshots, can you share them here? It's a specific day, or a period of time? If you are only getting specific dates, then that is likely the issue. There is a screen that shows peak power generation for current day/month/year and lifetime by panel. My installer has provided it to me a couple times upon request after consumers lost access to the SunPower site where you could see panel level detail.
The reason I ask is that I have over a years worth of 5 minute interval panel level data and over half the days, my peak production at any interval for a given day is 78% or less of the 320w(I have same panel as you, except 327-e series). So depending on what time periods you are seeing in your snapshots (ie. specific days versus YTD), 78% (270 of 320watts) is plausible. I will note the lowest peak production for any interval in any month was Nov at 89% (both this year and last year). I only had six days in November where at least some interval during the day peak production was at or about 78%. For December peak production for any day is currently sitting at 88%. Excluding Nov 2020, Nov and Dec 2021, I have at least one interval in a the rest of the months where I am at 99% of the 320 watts.

[ajonestx]

I don't know where you can test, but have a question for you. Do you have access to panel level monitoring or are you imputing panel level production based on data on the app/web divided by number of panels? If the later, maybe you just have one or two panels causing the issues (not hooked up properly, bad panel / micro)

Thank you for letting me know about not knowing testing options - I hope to find someone eventually.

I do NOT have full time access to panel level monitoring but have been able to obtain a couple of panel level power output screen shots from installers who have come out to check / repair other components over the last year. It appears that all are at least functional, just generally about 50 to 70 watts lower than the 300 to 320 watts that I saw at initial install. They did not seem to be knowledgeable about how to test a micro inverter.

If I can find someone to test each panel and each micro inverter (or show me how), I can verify what the issue is. Maybe I can find someone who is NABCEP certified... I think they are trained in this kind of stuff.

[ajzwilli]

I don't know where you can test, but have a question for you. Do you have access to panel level monitoring or are you imputing panel level production based on data on the app/web divided by number of panels? If the later, maybe you just have one or two panels causing the issues (not hooked up properly, bad panel / micro)

[ajonestx]

Why were the micros replaced after such a short service life ?

I don't know where I'd get a panel tested, but I'd guess the cost of doing so would far exceed the cost of replacing the panel and inverter. In any case, I'd first check the micro spec sheet and determine its max. output which may be close to 270 W.

But after I checked the micro spec sheet, the next call I made would be to the installer who replaced the micros.

The "original" micro inverters were replaced due to total failure (no explanation was given as to why or how they failed). I heard there were a lot of them that were replaced (other than mine).

The replacement micro inverter spec sheet lists 320w continuous AC output. That is the issue I am faced with... cannot figure out why the output is so low.

I called the installer who installed the original micro inverters, and they did not return my calls. I called the 2nd installer who put the replacements in and they told me that they did not know what they installed (I know... odd) - I had to hire another (third) installer to pull one of the panels down to see what was installed. I took pictures - MI-C-320-US208/240-10. I asked the third installer to test the panels, but they did not appear to know how to test a micro inverter.

I know this could be expensive, but until I know what the cost is, I cannot make a decision or move forward and cannot explain the low power levels. If you ever run across someone who can test the micro inverters, I would appreciate the reference.