solar panel output being restricted

4 Replies 3554 Views

I have a 6.6 kw panel system which during Dec and jan would produce up to around 3 - 3.5 kw of power at any point of time during the day which would amount to mid 30kwh to 42kwh for the day which covered any usage of our home plus would send excess back into the grid. excellent for me during the day but would obviously be using power at night and FIT no longer covered expense of night time usage.

I had a battery installed Tesla 2, which generally has meant that our grid power use has been nil until recently our power use has increased.

I am finding that our output from our panels hits the peak of around 3kw when full sun on panels (around 9.00 am) and then quite quickly output drops down and panel output reduces to at most 1.7 to 1.9kw.

with air con use kicking in due to the hot weather we are now using up everything in our battery and now using grid at night.

our system should be able to supply our battery and cover our air con during the day if it was still generating the 3.5 kw/40kwh per day it used to before the battery was connected.

what is going on that my panels output is being restricted? I'm only getting a third out of them than before the battery install.  

1 Reply 2897 Views

Hi @Kev_1 

Are you sure that your panel output power is related to the Battery install ?

I had a similar problem. I have 22 panels 11 panels per string.

I my power output dropped by about 30% all of a sudden last year and i could see it was limited to one of my 2 panel arrays.


To the point, the western part of my array 11 panels were exposed to a lot of grime dust bird droppings etc. Our area is still under construction with new houses still being built. High winds blowing dirt all over the place did not help a touch of rain not enough to clean the panels resulted in a sudden loss.


I got the panels inspected and was shown photos before the clean. They were a mess cleaning was carried out on all panels now I can once again hit my inverter limit of 8.2Kw production weather permitting and all is sweet. I will now get my panels cleaned once every 12 months.


I would get your panels checked for grime / bird droppings etc.


How old are your panels ?


You have a 6.6Kw system yet can only produce at best 3.5Kw ? What size is your inverter ? it should be a 5Kw unit if you have 6.6Kw in panels.


It is not adding up 6.6Kw in panels your inverter should be nudging 5Kw at its best unless the install was not up to standard ie: A neighbour has panels on the east and west side of his home in my street and they are on "ONE STRING" a dodgy install and explains his problem similar to yours in that he can not get past 3KW of production when he should be nudging 5Kw.


I would first get your panels checked for grime / bird droppings / lichen etc.

Then go from there.





I do not work for AGL, only trying to help where I can 


Plan:   Solar Savers

Dist:    Endeavour Energy

State:  NSW 

0 Replies 2887 Views

thanks for the info.

I have a 5kw inverter (fronius). My panels lie on a flat roof so I expect them to produce a little less anyway.

the drop in production happened at the time of installation of the battery. Prior to that each month's production mirrored that from the previous years months so I can only see a link between the two atm.

Regardless, you are right in that an inspection of the panel's cleanliness wouldn't go astray.

1 Reply 2878 Views

You don't mention where you are Kev, or what weather (cloud too) conditions were like on what might be the worst days.

Do you have an app that gives you production and consumption ?

Where are your figures from, an app for the solar / battery, or from the AGL app ?


We are in Adelaide, have 3 phase with 11.23kw Trina solar (optimised), 2 Solaredge inverters 5kw ea (Energy Hub and Genesis) on 2 phases.

We quickly realised to get the most of the solar we need to get a battery, that's VERY relevant here in SA with the huge discrepancy between peak charge and FIT.


It was installed early Nov, meter and all working fine early Dec.

Last Wed, 2 months after panels put up, I decided to give them a clean in between 2 same sunny days.

I cleaned them end of Wed, took meter and app readings daily as usual, and day 2 it made 5.5kw more.

Of course there may be variables, the panels generally had a slight coat of dust, one had a decent bird dropping on it, others had those small bird droppings in general over them.

Panels are optimised, so anything too large didn't affect others in the 2 inputs.


I figure I will clean the panels 3 x a year quarterly, skipping winter when it should be ok with general rain cleaning.


You don't say what excess you have to the grid, how quick / full your battery is charging each day.

I was told by a fellow quoting yesterday that air conds will drain a battery very fast, cool the home down through the day, keep it cool, turn off air cond when solar dips to not covering use.


Your problem appears to be related to the battery install ?

This has only happened since that was installed ?

If so, I would be getting the battery place back to check why this is happening, these people do much up wiring and it makes a big difference to how things work.


Our system app cbus was wired up single phase and nothing worked properly until a week and a half later when they came back to see why, fixed up in an hour or so.


You've obviously had the system long enough to compare previous periods, how does it go in Winter charging the battery ?

1 Reply 2858 Views
I’m in Adelaide. Right now at 12.30 clear sunny day and my solar is producing 1kw.
At 9.00am this morning it reached 2.5kw and just after 9.00 it started to reduce going down as low as .6kw and then came back up to 1.7kw before reducing again to around 1.3kw. as I said it is now at 1.0kw.
This seems to be a consistent thing in getting a peak reading around 9.00am and by 9.10am it starts to reduce and settle at around 1.2 to 1.7kw.
These figures are from the Tesla app as well as from the AGL app and my online account.

At the moment, even without running the air con, I can get back to about 80% capacity only and then of course sun goes down and battery use kicks in, drop to around 50% but then next day struggle to get battery capacity back up.

My panels have gone from producing high 30 - low 40kwh per day to low 20kwh per day.

The battery was installed through AGL so I’ll need to get a service docket raised to get the installer to come out (spoke to him yesterday and as the work was contracted to them by AGL they won’t come out independently to look at their handiwork).
1 Reply 2855 Views


Sorry to hear of your troubles with that.


Think you're on the right track, you'll have to push AGL to get the contractor out again to investigate.

We had this with our solar system company, although we knew their contractor from the install, had to get the contract-ee (new word there ha ha) that we had the deal with / paid to get them back.


I was looking at the AGL deal for a teslawall / gateway backup, the interest free deal is pretty good.

But we've decided to shop around, various options, get some feedback and possibly just save for a few months to cover it ourselves.


Trust AGL will get onto this and the contractor for you, that needs to be fixed and fast, especially now summer solstice has past and things will gradually reduce through the the Autumn / Winter (brrr).


Good luck, and please keep us posted here regarding how this gets solved.

1 Reply 2854 Views
Will do.
1 Reply 2746 Views





An update on this would be good.


Now John_T lives in Western Sydney, Lester lives Southern Suburbs Adelaide and I live in Northern Suburbs Adelaide.


I have 6.6kW system, 5kW inverter, 12 panels are on a north facing sloping roof the 12 other panels are on north / south flat roof.


Right at this time 8:30 SA time the angled panels are producing 343.6 volts at 2.8 amps (962 watts) and the flat roof panels are producing 411.1 volts at 0.4 amps (165 watts).


That comes out at 1126 watts (1.126 kW) my inverter tells me that I am producing 1057 watts, this gives my inverter an efficiency of 1057/1126 or 94% at this time.


Eight minutes later I am producing 1.927kW because the sun has risen slightly and the partial shadow on the flat roof panels has reduced with sloping panels 348.6 volts at 3.0 amps and flat panels producing 354.7 volts at 2.7 amps.


This will continue to grow until around 10:00 when it will reach its peak 5kW, at this time the inverter will get hotter as it dumps the excess power then around 14:30 when production falls below the 5kW output.

On hotter days the panels themselves get hotter and reduce their output and peak time will become 11:30 to 14:00 thus getting less output on a hotter day.


Looking at the graphs of my output I can see that I have been having cloudy days as you can see the output drop and clouds reduce the output.


Below are my daily stats for this month

Daily Statistics
4.856 From Grid
26.982 Exported 
9.657 Generated consumed
36.639 Daily Generation 


And for the same period last year

Daily Statistics
4.061 From Grid
25.305 Exported 
3.828 Generated consumed
29.133 Daily Generation 


You can see the effect of the overcast days in the figures.


Anyway, you need to contact AGL directly as your post has not flagged any interest from AGL staff.


You can contact AGL via the methods listed at : Contact Us 

Click on the link and it will start a new web page for you.


If you log into your account you can message then or start a chat session from it.


Its now 09:15 panels are producing   340.4v at 4.6A (1.566 kW)  and 352.8v at 4.0A (1.411 kW) for 2.86 kW output, core temp of the inverter is good only at 31C at the moment with outside temp of 20C

Cheers Neil

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1 Reply 2743 Views

I’m in Mile End in Adelaide and the stats you have for your property is similar to what my system was producing prior to the battery fit.

I’ve been in contact with AGL and provided them with a range of daily and monthly data from pre and post battery fitment and am just waiting for them to get back to me (will be emailing them today as they have had a few days now) to arrange someone to check the system.

Currently, each day the system is reaching 2.8 kw at around 9.00 - 9.30 irrespective of cloud cover and then within 10 - 15 minutes it drops off a cliff and settles down around 1.5kw for the rest of the day!

1 Reply 2736 Views

Like Neil said above, no luck with AGL representatives here working with you yet, so best get onto the AGL chat or phone to sort asap Kev.

It's frustrating, we had to organise our own meter upgrade, rather than the solar co doing it, and then there was a minor wiring issue which cost us a week and a half of new solar benefit.

At least all working now ok, but if / when we get a battery, will be very careful to try and ascertain if the installer actually has half a clue about the ins and outs of 3 phase and making sure it's right from the start.

Keen to se how AGL handle this for you, it should be a priority on their part.