-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Why is our solar production getting cut off?
- Thread starter jboy210
- Start date
If it were cloudy I would have no issue. The issue is similar graphs occur on numerous bright and sunny days.
I am not saying I know the answer, but there were times I thought there were no clouds, but when I looked closer, at times they were way up there. Just have to keep collecting dataIf it were cloudy I would have no issue. The issue is similar graphs occur on numerous bright and sunny days.
If it were cloudy I would have no issue. The issue is similar graphs occur on numerous bright and sunny days.
I think there is something wrong with your production. The peak does not seem high enough for that size if system. That said, does your roof have a steep pitch?
The roof is not particularly steep. It is easy to walk up and down without fear of slipping (at least when dry).
Last edited:
I don't mean to suggest that this is a good idea since I don't know how you'd safely measure, but can somehow obtain a reading at high noon to measure the DC coming from the south-facing array before energy hits the inverter? I don't now how your DC home runs are or whether you can even backstab one of the connections with a voltmeter.
Butttt, if you could.... then you can isolate if this issue is because the array isn't pushing out enough DC current relative to their pitch/exposure , or if your inverters are clipping or not at the efficiency you'd expect.
My system is rated 7.935 kWp DC (23 panels x 345 watts)...
but only 6.679 kWp AC (23 panels x 1.21 amps per Enphase IQ7+ x 240 volts)...
Or... 1.19 DC/AC ratio
Since it looks like you're clipping well below the output of even one of your roof planes, I think it'll help to isolate if this is a DC problem or AC problem.
Edit: I guess to H2ofun's comment that it's not possible to achieve rated spec, I believe it is possible to get the rated spec if your panels are on a single roof plane and you have zero trees or obstructions
Butttt, if you could.... then you can isolate if this issue is because the array isn't pushing out enough DC current relative to their pitch/exposure , or if your inverters are clipping or not at the efficiency you'd expect.
My system is rated 7.935 kWp DC (23 panels x 345 watts)...
but only 6.679 kWp AC (23 panels x 1.21 amps per Enphase IQ7+ x 240 volts)...
Or... 1.19 DC/AC ratio
- According to the Tesla app today, at high noon I "clipped" and got pegged at 6.90 kW AC.
- According to Enphase Enlighten today, at high noon I "clipped" and got pegged to 6.80 kW AC.
Since it looks like you're clipping well below the output of even one of your roof planes, I think it'll help to isolate if this is a DC problem or AC problem.
Edit: I guess to H2ofun's comment that it's not possible to achieve rated spec, I believe it is possible to get the rated spec if your panels are on a single roof plane and you have zero trees or obstructions
Last edited:
Ben W
Chess Grandmaster (Supervised)
Inverter clipping can definitely happen due to a bad inverter (one of the internal power modules going offline), but it will look very obvious. This was my system a few days ago. Even with my half-broken system though, on a sunny day, I'm still getting about 75% of the daily production (total area under the curve) I would get if it were unclipped.
FWIW, this is a Fronius inverter that had been replaced/repaired about five times under warranty, and is sadly now out of warranty. (My 4.5kW SolarCity array was installed in 2009.) I'll probably get a new inverter pretty soon, and am considering adding another 4kW to a different part of the roof. New panels are literally twice as efficient now as they were then, 22% vs 11%!
One oddity: my PowerWall consistently reports 2.1kW solar power generation during these clipped peaks, while the solar part of the Tesla app reports only 1.8kW. I'm not sure where that 15% discrepancy comes from. And I would have expected, if anything, it would be the other way around. (E.g. 2.1kW solar production into the inverter, 15% losses converting to AC, 1.8kW into the PowerWall.) Tesla service doesn't seem to know either. It's a mystery.
FWIW, this is a Fronius inverter that had been replaced/repaired about five times under warranty, and is sadly now out of warranty. (My 4.5kW SolarCity array was installed in 2009.) I'll probably get a new inverter pretty soon, and am considering adding another 4kW to a different part of the roof. New panels are literally twice as efficient now as they were then, 22% vs 11%!
One oddity: my PowerWall consistently reports 2.1kW solar power generation during these clipped peaks, while the solar part of the Tesla app reports only 1.8kW. I'm not sure where that 15% discrepancy comes from. And I would have expected, if anything, it would be the other way around. (E.g. 2.1kW solar production into the inverter, 15% losses converting to AC, 1.8kW into the PowerWall.) Tesla service doesn't seem to know either. It's a mystery.
Last edited:
bkp_duke
Well-Known Member
I would have Tesla investigate. This seems WAY too low for a 12kw system.
This is an apples to oranges comparison, but here is what my 16 kw SunPower system produced on that day (peaked at 14.7 kw):
This is an apples to oranges comparison, but here is what my 16 kw SunPower system produced on that day (peaked at 14.7 kw):
No way can one say system size expects X. Directions. Angles, shading, etc. I will never get close to my spec size because of these type of things
bkp_duke
Well-Known Member
50% is still WAY too low for his 12 kw system. This time of year, WAY too low given what he has described.
I'm almost inclined to believe the smaller inverter is turned off.
Silicon Desert
Well-Known Member
yo J, I know you to be a really smart engineer, so maybe you have thought about this... I wonder if what you are seeing is the same thing I see on my house down in San Diego. Half my modules are facing West and half of them somewhat South. Reason for the West facing modules is to get power in the later afternoon due to the TOU schedule.
What happens down there is that around mid day as the sun starts showing less on the South panels, the energy drops from those, but is balanced out by the West facing panels getting more sun. This happens for a period of about an hour or more. And small variations in the curve where it flattens is due to minor variation in the atmosphere, temperature, etc. So I am wonder since I think you mentioned having panels facing different directions if this is part of the reason for the flattened curve? Your graph does look somewhat like my home down south, and I know that system is working perfectly.
That is a good thought. The house faces North/South almost perfectly and we do have active tiles on both sides. So something to consider.
The system is a solar roof with about 8kW on South facing roof and the remainder on North facing. We did have days of 80+ kWh but closer to the equinox.
bkp_duke
Well-Known Member
We are only 9 weeks or so from the equinox right now, and you are less than half of that 80 kwh. Something just doesn't smell right on this one.
Something definitely seems low. I know we are on the other side of the country, but our 8.2 kW roof (4.1 kW each N and S) is producing as much or more than your 35 kWh number on sunny days. With a combination of the lengthening days towards the solstice (I'm assuming that's when you are hitting 80+ kWh) we have had several days this month above 35 kWh, and the max we have ever hit was 43 kWh (though we got PTO in July, so some June days might have produced more if running on-grid), so barely over half what you have seen. And I have not seen anywhere near that level of fluctuation in output on a truely sunny day.
Yeah, based on the low production, I guessed earlier that maybe the smaller inverter wasn't working (or at least a string or two). Less than 50% is way too low at this time of the year. Our system was at 50% vs. last year's max production over two months ago, in the first week of February. Currently our system producing at 91% of last year's maximum production. We did have some issues last year with dirty power causing our Powerwalls to kick in a lot (like 3 dozen times a day) and shut down our solar system, so it's possible our maximum production will be a lot higher this year. Taking that into account and estimating a new maximum production value, our system is currently producing at least 75% of last year's peak production and we hit 50% back in the third week of February.
There seems to be a consensus that we should be producing more and perhaps the inverters are not correct. I tried turning them off one by one and the production does drop on inverter shutdown, and climb back up when I bring each inverter back online. So at this high level of testing the inverters are outputting. Is there a way to test them further, or is it time to have Tesla check it out? Perhaps I should take a phone down there with the Delta app and let it record for a day?
Last edited:
You might try contacting some of the members, such as @Bozon and @jat255 , who've posted in Delta M-4, String drops out to zero for 2 hrs ? and who are reporting production issues with their Delta-M inverters. I think at least a couple posters have app access (M Professional?) which lets them see which strings aren't producing. I have 3 Delta Solivia inverters, not the M series, so I haven't bothered trying download the app or try to monitor string production yet.
If you use the M Professional app, connect with the "6532" code, and activate the advanced features, you should be able to see historical data for the past 10 days for each string and also see the inverter log.
Similar threads
