Am I getting the power I should?

[RussellW]

Hello everyone,
I just had a 13.2 kW solar panel system installed in my home in New Jersey. On the brightest day with the sun at 90 degrees from the panels, the best I can get is just above 10 kW (and that rare). Most of the time in the 9's.
I just wanted to see if anyone else has had the same experiences with their solar.
I assumed I would get close to 13.2 in the summer with direct sun
Thanks in advance!
Russ

 

[wwhitney]

What is your inverter size? Probably 10 kW.

In which the case, most likely, the frequency with which your panels could produce over 10 kW (cool day, sun very close to 90 degrees to panel), is low enough that the energy production lost (clipping) is of low economic value.

Cheers, Wayne

 

[jjrandorin]

Hello everyone,
I just had a 13.2 kW solar panel system installed in my home in New Jersey. On the brightest day with the sun at 90 degrees from the panels, the best I can get is just above 10 kW (and that rare). Most of the time in the 9's.
I just wanted to see if anyone else has had the same experiences with their solar.
I assumed I would get close to 13.2 in the summer with direct sun
Thanks in advance!
Russ

The answer to your thread question, is that "with the information provided we dont know for sure, but what we DO know for sure is that just because you have 13.2kW of panels, it doesnt mean you will ever hit that number as peak power generated:.

Or, in a TL; DR manner, the answer to "Am I getting the power I should be in my PV system?" is: "Most likely yes".

See this recent thread which is the same basic question of "I thought my system size of X would generate peak power of X?"

7.2 kw system generates only 4 kw

I am from San Diego. Have enough sunlight but my 7.2 kw system generates only 4 kw rarely generates 5 kw. Appreciate any tips to maximize production.

teslamotorsclub.com

 

[ptdusn]

I have a 27 panel 9.45k system with Enphase inverters. The other day when the Sunrun Tech was here replacing the Neurio meter, I got him to connect to the combiner and at Noon, (here in AZ), with the sun directly overhead, all 27 panels were producing 245-246w. So it looks as if i will never get over 6.8kw.

 

[holeydonut]

I have a 27 panel 9.45k system with Enphase inverters. The other day when the Sunrun Tech was here replacing the Neurio meter, I got him to connect to the combiner and at Noon, (here in AZ), with the sun directly overhead, all 27 panels were producing 245-246w. So it looks as if i will never get over 6.8kw.

If all your panels are facing the same direction and you have no shading, that seems kind of low.

with iq7+ micros, it’ll be a peak of
27 panels x 1.21 A x 240 volts = 7.8 kW AC

Does the Enphase Enlighten data show the panels all peak at 245 watts?

 

[jboy210]

Hello everyone,
I just had a 13.2 kW solar panel system installed in my home in New Jersey. On the brightest day with the sun at 90 degrees from the panels, the best I can get is just above 10 kW (and that rare). Most of the time in the 9's.
I just wanted to see if anyone else has had the same experiences with their solar.
I assumed I would get close to 13.2 in the summer with direct sun
Thanks in advance!
Russ

It might help if you posted the layout of the panels and inverters, and the solar production curve from the Tesla app. Also, is there any shading present? What is the annual production listed for the system?

 

[ptdusn]

If all your panels are facing the same direction and you have no shading, that seems kind of low.

with iq7+ micros, it’ll be a peak of
27 panels x 1.21 A x 240 volts = 7.8 kW AC

Does the Enphase Enlighten data show the panels all peak at 245 watts?

Don't know the peak but the sun was overhead.

 

[holeydonut]

Don't know the peak but the sun was overhead.

I guess I have a a couple of thoughts.

1) Does your "custom solar design" tell you what Enphase microinverter you got? It should say IQ7+ or "IQ7PLUS". I hope they didn't sell you IQ7 (no plus)
2) Did you ever get set up on enlighten.enphaseenergy.com ? Or did Sunrun only get you set up on my.sunrun.com ?

Sunrun.com is a very dumbed down interface... you'll want to get access to Enlighten if you can. I had to make a few extra calls to Sunrun support to get set up on Enlighten.

The reason this is important is that Enlighten will report the per-panel output in graphical form. For example, here's a snippet of what I see after changing the menu to "Power" for yesterday June 20. Then I scrolled the graph's time axis over to high noon.

An Enphase IQ7+ at peak per its spec sheet can harvest 1.21 amps at 240 volts. This is about 290 watts. But heat, Q-cable junctions, and other mitigating factors erode real-world performance, you would expect more like 280 watts measured at the Enphase Envoy for a given IQ7+ micro. So, at whatever your peak-time is, I think you would have expected to see something around 280-290 watts.

But since you only see around 245 watts at peak, I wonder if they put in IQ7 instead.

 

[charlesj]

To @ptdusn and @RussellW :
-- Heat is the enemy of solar generation. Enphase panels and displays if you have them is capable of showing panel/inverter temperatures.
I have Enphase. The other day outside air temp was about 20C(68F) but pane/inverter temp was close to 50C. So, outside air temp is not an indicator of panel/inverter temp.
--Your roof has an angle to them, most of them anyhow and most face towards the south. This time of year the sun is well past towards the north to be 90 deg perpendicular to your panels at what you think might be solar noon. That doesn't help, just as when the sun is coming up before high solar noon and after it starts to set. So this doesn't help either.
You could Google sun arc data to see your location and sun angle is during the year.
--Your panel rating is not real world rating.
--Your inverter is the limiting factor, not your panels unless inverters are the same size as panel rating totaled in which case your panel is.
--What you think might be a clear sky may not be to the sun particles that generates electricity.

All in combo will affect production.

 

[holeydonut]

To @ptdusn and @RussellW :
-- Heat is the enemy of solar generation. Enphase panels and displays if you have them is capable of showing panel/inverter temperatures.
I have Enphase. The other day outside air temp was about 20C(68F) but pane/inverter temp was close to 50C. So, outside air temp is not an indicator of panel/inverter temp.
--Your roof has an angle to them, most of them anyhow and most face towards the south. This time of year the sun is well past towards the north to be 90 deg perpendicular to your panels at what you think might be solar noon. That doesn't help, just as when the sun is coming up before high solar noon and after it starts to set. So this doesn't help either.
You could Google sun arc data to see your location and sun angle is during the year.
--Your panel rating is not real world rating.
--Your inverter is the limiting factor, not your panels unless inverters are the same size as panel rating totaled in which case your panel is.
--What you think might be a clear sky may not be to the sun particles that generates electricity.

All in combo will affect production.

Yeah, that's one of the reasons I wanted ugly stand-off mounting instead of the cool/sexy low-mounting with fancy pants skirts. I get like an extra 4% with these fugly mounts due to the extra air flow.

Standoffs racking can add over 4% vs flush-mount racking

Thanks to @Redhill_qik for posting the link about the CSI-EBPP estimator: http://www.csi-epbb.com/ I guess this tool is a similar thing to PVWatts, and is used by California utilities to do some weird maths around their solar/incentive programs. You can punch in your array spects and it'll...

teslamotorsclub.com

But ptdsun's issue looks much more serious than just a 4% loss due to the natural convection/cooling on the Enphase micros.

 

[wwhitney]

--Your roof has an angle to them, most of them anyhow and most face towards the south. This time of year the sun is well past towards the north to be 90 deg perpendicular to your panels at what you think might be solar noon.

For reference, the OP appears to be at about 40 degrees north latitude. That means on the summer solstice, the sun's elevation angle will be 90 + 23.5 (earth's tilt) - 40 (latitude) = 73.5 degrees. So if the roof slope is 16.5 degrees, or 3.5 in 12, and the roof is oriented due south, the sun will be perpendicular to the roof at solar noon on the solstice.

Cheers, Wayne

 

[ptdusn]

I guess I have a a couple of thoughts.

1) Does your "custom solar design" tell you what Enphase microinverter you got? It should say IQ7+ or "IQ7PLUS". I hope they didn't sell you IQ7 (no plus)
2) Did you ever get set up on enlighten.enphaseenergy.com ? Or did Sunrun only get you set up on my.sunrun.com ?

Sunrun.com is a very dumbed down interface... you'll want to get access to Enlighten if you can. I had to make a few extra calls to Sunrun support to get set up on Enlighten.

The reason this is important is that Enlighten will report the per-panel output in graphical form. For example, here's a snippet of what I see after changing the menu to "Power" for yesterday June 20. Then I scrolled the graph's time axis over to high noon.

View attachment 819233

An Enphase IQ7+ at peak per its spec sheet can harvest 1.21 amps at 240 volts. This is about 290 watts. But heat, Q-cable junctions, and other mitigating factors erode real-world performance, you would expect more like 280 watts measured at the Enphase Envoy for a given IQ7+ micro. So, at whatever your peak-time is, I think you would have expected to see something around 280-290 watts.

But since you only see around 245 watts at peak, I wonder if they put in IQ7 instead.

They put IQ7-60-x-US. Not the pluses

 

[ptdusn]

I guess I have a a couple of thoughts.

1) Does your "custom solar design" tell you what Enphase microinverter you got? It should say IQ7+ or "IQ7PLUS". I hope they didn't sell you IQ7 (no plus)
2) Did you ever get set up on enlighten.enphaseenergy.com ? Or did Sunrun only get you set up on my.sunrun.com ?

Sunrun.com is a very dumbed down interface... you'll want to get access to Enlighten if you can. I had to make a few extra calls to Sunrun support to get set up on Enlighten.

The reason this is important is that Enlighten will report the per-panel output in graphical form. For example, here's a snippet of what I see after changing the menu to "Power" for yesterday June 20. Then I scrolled the graph's time axis over to high noon.

View attachment 819233

An Enphase IQ7+ at peak per its spec sheet can harvest 1.21 amps at 240 volts. This is about 290 watts. But heat, Q-cable junctions, and other mitigating factors erode real-world performance, you would expect more like 280 watts measured at the Enphase Envoy for a given IQ7+ micro. So, at whatever your peak-time is, I think you would have expected to see something around 280-290 watts.

But since you only see around 245 watts at peak, I wonder if they put in IQ7 instead.

Also, have gone to enlighten.enphaseenergy.com, but haven't gotten the info yet

 

[holeydonut]

They put IQ7-60-x-US. Not the pluses

Damn. I guess your system is performing as Sunrun implemented. Since they put in inverters that cap out at 1.0A each, your AC production is capped at 27 x 240 = 6.5 kW AC. The panels may each be 350 watts = 9.45 kW DC, but you're getting clipped at peak time down to 6.5 kW AC So, Sunrun put in a 1.4 DC:AC ratio on you.

There are some other users on TMC that have a ratio around this because they have mega-huge roofs with lots of solar compared to what they actually need to harvest for their annual NEM. So, the higher ratio results in up front investment savings since they can run a cheaper inverter. Also, this means the solar panels can degrade over time, and not really affect the total produced kWh since the inverter is clipping away excess production anyway.

However, I think most "normals" would want a 1.2 DC:AC ratio or less if the cost is right. I was told by the Sunrun ops-lead (here in Northern California) that Sunrun's designers usually shoot for a 1.2 DC:AC ratio.

It's about a $20 per inverter cost difference (retail pricing), so this is probably less than $540 with Sunrun's purchasing power and scale for your 27 micros.

I wish the solar industry would make a habit of asking the homeowner if they think getting a few more kWh production is worth the extra cost of a lower DC:AC ratio. But they simply don't... they rely on the homeowner to "do their own research" (har).

TLDR, with Enphase IQ7, your system is performing as your designer intended, and should produce the annual estimated kWh on your contract. But they could have freed up more kWh (for a price) by bumping you up to IQ7+.

 

[charlesj]

They put IQ7-60-x-US. Not the pluses

What was your design criteria? Was it limited by anything?
With that DC ratio, you should be producing peak power over a longer time period in the middle of day.
Can you post a snapshot of a production graph for a good day to get an idea how much clipping you are having?

 

[holeydonut]

What was your design criteria? Was it limited by anything?
With that DC ratio, you should be producing peak power over a longer time period in the middle of day.
Can you post a snapshot of a production graph for a good day to get an idea how much clipping you are having?

Yeah, I guess it's worth plugging into PVWatts to see what extra kWh would be produced with a 1.2 ratio vs 1.4.

If I punch in PVWatts on my own array, I lose 100 kWh (year 1) with 1.4 instead of my installed 1.2 ratio. Since I'm already a net NEM consumer, this is basically stuff I'd have to import at PG&E's blended retail EV2A rate of bout $0.35. So it'd take me about 15 years to break even on ~$500 of install-cost on the IQ7+.

I don't think ptdsun would break-even given Arizona's much cheaper electricity rates. So maybe he's better off with his IQ7's. Unless he hates his poco as much as I do, and his ROI is not a monetary amount.

 

[ptdusn]

What was your design criteria? Was it limited by anything?
With that DC ratio, you should be producing peak power over a longer time period in the middle of day.
Can you post a snapshot of a production graph for a good day to get an idea how much clipping you are having?

I've been peaking at 6.7/6.8kW and now getting 60kW a day. Prior to the 100-degree weather, we have been sending 350-375kW back to the grid for a nice discount, ($25 electric bill), so overall have been saving $35-$50 a month compared to our bill before solar.

 

[getakey]

I've been peaking at 6.7/6.8kW and now getting 60kW a day. Prior to the 100-degree weather, we have been sending 350-375kW back to the grid for a nice discount, ($25 electric bill), so overall have been saving $35-$50 a month compared to our bill before solar.

here in PG&E world, I save $700 to $900/ month in the summer

 

[charlesj]

I've been peaking at 6.7/6.8kW and now getting 60kW a day. Prior to the 100-degree weather, we have been sending 350-375kW back to the grid for a nice discount, ($25 electric bill), so overall have been saving $35-$50 a month compared to our bill before solar.

Nice curve. Looks like the inverters are clipping there for a number of hours, that relatively flat top portion.
Also, with your DC:AC ratio, you should be getting that peak output for much more days than otherwise during the year.