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Is this a plausible amount of input from the panels?

thebeavesknees

thebeavesknees

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Joined
Sep 5, 2023
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132
Location
SE PA
Hi, all!

I got some fairly strange numbers today that I would like to have some feedback on. Is it possible to get ~725W input from two REC 405W rated panels (two in series currently for 810W nominal) in February in Pennsylvania? That works out to be 88% of the rated capacity, and I find the entirely suspect. Just the day before under similar weather conditions, I saw a consistent peak of about 520W, or ~62% of the nominal rating of the panels. These are nearly flat mounted on the roof of my travel trailer, and not pointed in the best orientation, and even have a partial occlusion due to a roof peak near noon.

3048LV-MK_05.png

The 520W seems at least possible and matches well with the JK BMS and shunt readings at the time. I don't have logging via the shunt yet, and I was at work while these very high peaks happened, so I don't have any corroboration from other sources that this is actually what was happening.

Here are the crappy screen shots of crappy WatchPower for most of the day:

3048LV-MK_06.png

3048LV-MK_07.png

3048LV-MK_08.png

SO is that plausible or is it just junk data from watchpower or the 3048 itself?
 
Last edited:
ScrotusGobbleBottom said:
I received sustained 106% of my panel rating in Feb. Very much unlike June and July. February seems to be a fair to good month for solar. The cooler temps help out a lot here in Wisconsin.

Seems totally plausible.
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Dang. That's wild. I am still very new to all this, and the learning curve is steep and full of twists and turns that I certainly wouldn't have figured out on my own!
 
thebeavesknees said:
Dang. That's wild. I am still very new to all this, and the learning curve is steep and full of twists and turns that I certainly wouldn't have figured out on my own!
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Im right behind ya. I havent done a whole year yet.. Ive done june to nov at my old house and june to now at my new house. I havent covered all the months lol
 
For me, I get occasional spikes > panel listings. A few minutes, a few times a year kind of thing. It's usually with really bright sun and fluffy white clouds and COOL TEMPS. This month (Feb) I got a short 12.6kw spike on 14.5kw array but don't run more than 12.0kw will full, steady sun.
 
thebeavesknees said:
The 520W seems at least possible and matches well with the JK BMS and shunt readings at the time.
Click to expand...
So there is something to be said here. Lets say I was pulling in 1000 watts, the shunt on my battery and my BMS would never say 1000 watts because of losses. You will lose just a bit in the wire to your battery, but the biggest loss is the DC/DC conversion. Your PV is at 90V but your battery almost certainly wouldnt like that. It has to be converted to your battery charge voltage. Then there is the wattage "cost" of your inverter and charge controller being on. At least on my system, all the losses are NOT factored into my PV input graphs, or history.

The BMS and any shunts give you a good enough picture of net gains.
If I was getting 1000 watts of PV input, my shunt would say something like 850 ish or maybe even less.
In actuality, think of it like the gross and net earnings on a paycheck lol One is a fancy big number that would be nice to have, but you dont get it.
 
I've seen a 1000W array put out 1300W for a few minutes several Februarys ago. I think it was cloud lensing. I only have one 1000W array online, and I rushed outside to look at the sky when I saw 1300W. Wispy Cirrus clouds did it. When the clouds drifted away, output dropped down to ~850W, which is more in line with what I would expect. I've only experienced it once, and it hasn't happened again since while I was watching my controller. The cloud lensing, plus cooler than normal panels could completely explain what you saw.
 
MichaelK said:
I've seen a 1000W array put out 1300W for a few minutes several Februarys ago. I think it was cloud lensing. I only have one 1000W array online, and I rushed outside to look at the sky when I saw 1300W. Wispy Cirrus clouds did it. When the clouds drifted away, output dropped down to ~850W, which is more in line with what I would expect. I've only experienced it once, and it hasn't happened again since while I was watching my controller. The cloud lensing, plus cooler than normal panels could completely explain what you saw.
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Yes I have a 3600 watt array and saw 3900 for about a minute. Then it settled down to 3600 or so
 
Absolutely possible, multiple times I've seen one of my MPPTs clipping at 5500W with 5180W of panels on my ground mount.
I questioned the accuracy of the MPPT so much I picked up a Victron 100/20 and added 2 of the same 370W panels to a temporary ground mount.... (maybe it was an addiction for more power at play too). Check out the P max 4 days ago, some great cloud edging. The past 3 days have been overly sunny.
Screenshot_20240221-213758.jpg
 
Another update on this:

With the cold, clear days with a sun higher in the sky, I've had several days of sustained, higher than sticker rating output from the panels. It's honestly been shocking to see how well just the two panels are performing when it's cool/cold and sunny. The peak, so far, was 875W. I'm regularly seeing at least half an hour at over 800W. I never knew this was possible, so, I'm very pleased. 😁
 
thebeavesknees said:
I never knew this was possible, so, I'm very pleased.
Click to expand...
Yes! BUT, summer is typically a lot worse at sustained peaks. For instance, here in March, I can hit 100% just about any good day. In the summer I never see 100% rated. That could be because I have my panels angled at 42 degrees for fall and winter being the priority. Alas I am too lazy to move them in summer :)
 
Well, mine are essentially flat mounted in an RV roof... So there's that. LOL

This is the first spring season with the system and is all new, so I'm looking forward to seeing how it performs as the seasons change. ☺️
 
thebeavesknees said:
Well, mine are essentially flat mounted in an RV roof... So there's that. LOL

This is the first spring season with the system and is all new, so I'm looking forward to seeing how it performs as the seasons change. ☺️
Click to expand...
My first winter.. I was super depressed in nov, saying goodbye to free money.. :(
But then February injected a lot of hope and cheer! I got some of the best numbers I have seen.

If your panels are on an RV roof, summer will be your best numbers I think.
 
ScrotusGobbleBottom said:
My first winter.. I was super depressed in nov, saying goodbye to free money.. :(
But then February injected a lot of hope and cheer! I got some of the best numbers I have seen.

If your panels are on an RV roof, summer will be your best numbers I think.
Click to expand...
Yup. I'm going to be limited with what I can do on the roof, since I can only fit 4 panels of the current type up there. Once I move elsewhere, I'll be able to install a ground mount system and will simply add that to the input of the second 3048LV-MK. But, yes, I'm expecting to see more total input as the sun climbs until late June. 😁
 
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