Hi all

i just got 6 JA 330w panels installed in 3s2p configuration. The most wattage i’m getting at 12:30 is around 1200 to 1300 watts, on a clear day, even with a 2kw load registered on the inverter. I was expecting it being a tad higher, maybe at around 1500w. What would you expect to see on a clear may day generated from the above number of panels?

I’m using a mecer inverter (axpert) 5kva on SbU priority

Thanks all

15 minutes ago, TommieWol said:

What would you expect to see on a clear may day generated from the above number of panels?

If installed correctly I would expect between 1500 and 1550 watts. Depending on where you stay, the orientation of your panels, the angle they are mounted at ect... Your location will also determine at what time of the day you can expect max production , way up north where I stay, it is at 11H45 so at 12h30 my PV start showing a slight decrease in production already. 

Can you maybe tell us more about the physical installation as well as cables used from the PV to the inverter?

22 minutes ago, TommieWol said:

just got 6 JA 330w panels installed in 3s2p configuration. The most wattage i’m getting at 12:30 is around 1200 to 1300 watts, on a clear day, even with a 2kw load registered on the inverter. I was expecting it being a tad higher, maybe at around 1500w.

Properly oriented, batteries not full (and/or enough loads) at this time of the year I would expect 0.8*330*6 ~= 1600W. Give or take depending on whether conditions. Probably not much more. Most days I peak at around 75% of installed capacity, so more like 1450W.

It also depends a bit on your MPPT. @Jaco de Jongh told me after he upgraded to a different brand his setup seems to make much more... is still still your observation Jaco?

10 minutes ago, plonkster said:

is still still your observation Jaco?

Definitely still the case. Thanks for bringing it up, so use to it, I don't even think about that anymore.. 

Thanks guys, the panels are installed on a flat roof with about a 15 degree north facing angle. No shadows over it for 90% of the day, and lastly, in Johannesburg

I’m not 100% sure of the cables, from what i can see on it is some german made 6mm (could be 8, writing on it is a bit hard to read) but looks closer to 6.

Not sure if it matters but the battery is a 4.8kw lithium connected to the mecer inverter

 

1 hour ago, TommieWol said:

i just got 6 JA 330w panels installed in 3s2p configuration.  ... I’m using a mecer inverter (axpert) 5kva

Any chance for experimentation you could knock out one panel on each string? So then it's 2S2P (obviously you'll need to scale your results to what you might get with 2S3P).

I'm starting to think that 3 x typical 330 W panels (which I assume are all 72 cell) are too high in voltage (especially when not all that hot) for 145 V Axperts.

6 panels is ideal to make the change (3S2P to 2S3P) if needed (but still the hassle of all that extra wiring). Those with 3S3P can only go to 2S4P with a wasted panel, or the hassle of finding and mounting a compatible extra panel for 2S5P.

There has been at least one other comment like this (but with 3S3P) just recently. In searching for it, I came across this post which said:

"On my own system I tested 9 panels 3s3p and 10 panels 2s5p and saw a small improvement with the 2nd setup - thus my opinion that it is not worth the risk with 72mod panels." Hopefully, the results were scaled for the 9 versus 10 total panels before comparing.

I believe that there are 60 cell 300 W panels these days. These are ideal for Axperts in 3S configuration. Of course, such a level of choice might not be practical in South Africa at present...

Edit: the MPPT range is stated as 60-115 V, though firmware reading seems to indicate that derating happens linearly from 130-145 V. Note that they derate to zero power at 145 V. If Vmppt is above 130 V, then you will be losing power from over-voltage. This will I believe get worse in winter, when you need panel power the most. You will also be stressing the SCC components (capacitors, MOSFETs) more at the higher voltage. Axpert SCCs have no way of disconnecting panels if excessive panel voltage is detected. There may be additional derating due to high temperature (of the SCC heat-sink, not the panels).

Edited May 5, 20197 yr by Coulomb

What you should do is look at specific yield. You should be getting between 1400 -1600kwh/kwp over 12 months. This obviously varies according to region. If you get to that, then don`t worry about the module getting to it`s max because that is dependent on too many vairables.

I’m not yet at the confidence level to mess with the wiring yet, so would rather not. Haha.

I did notice that the highest voltage the inverter registers coming from the panels are 120v, so not hitting the limit yet from what i understand of the inverter.

I’m struggling to get the data from the inverter to my pc to pull graphs at the moment, so will update when i have More data.

1 hour ago, plonkster said:

It also depends a bit on your MPPT. @Jaco de Jongh told me after he upgraded to a different brand his setup seems to make much more... is still still your observation Jaco?

Now that is a loaded question and accompanying answer.

Who else missed it? 

6 minutes ago, TommieWol said:

highest voltage the inverter registers coming from the panels are 120v

So still 10 V to go till power starts limiting. Though that is over the manufacturer's MPPT range limit (115 V). I don't have firmware for the latest SCCs (U2 version 4.12), so it's possible that they start derating at lower than 130 V. Also, even if derating isn't happening, anything over 115 V may not find the true maximum power point for other reasons.

But yes, that data indicates that it may not (yet) be limiting due to panel voltage, so other factors may be in play.

1 hour ago, The Terrible Triplett said:

Now that is a loaded question and accompanying answer.

I just didn't see a reason to go into the specifics, but okay... here goes 🙂

Jaco had an Infini Super. He had two in fact. That thing appears to be a little different to your run-of-the-mill Axpert. It did the usual cycle of blowing up one of the two in-parallel units, going for repair, coming back, repeat in a few months. Jaco got tired and installed some blue stuff. Next morning he called me and said he could not believe how much better the new MPPTs are doing...

So the MPPTs in the Infini-super are rubbish, or at least the ones he had. But you also know that some guys actually benchmarked some Axperts before and found them to be close to the BlueSolars... so this is not another dig on the Axperts. It seems merely that quality varies from model to model (yeah okay... that's a bit of a dig).

So I am suggesting that a low yield could also be due to having such an MPPT. Of course I had also completely forgotten that the Voltronic units start to derate above 135V. And the 15° angle is also a little suboptimal for this time of year. So all in the total numbers don't sound too far off. It's on the low end, I think, but not completely out of the bounds of plausibility.

Thanks everyone for sharing their knowledge! It is awesome help for a newb like me and reassuring that we can but ask a question and people just help. Love it. 

5 hours ago, TommieWol said:

Hi all

i just got 6 JA 330w panels installed in 3s2p configuration. The most wattage i’m getting at 12:30 is around 1200 to 1300 watts, on a clear day, even with a 2kw load registered on the inverter. I was expecting it being a tad higher, maybe at around 1500w. What would you expect to see on a clear may day generated from the above number of panels?

I’m using a mecer inverter (axpert) 5kva on SbU priority

Thanks all

I have the exact same setup as you, but I have them configured as @Coulomb has suggested by a 2S3P configuration.

My peak power today was 1631W and in summer I get a peak of +-1800W in ideal conditions.

The mounting angle makes quite a difference, you will probably find too the peak efficency for the MPPT I'm guessing is about 70-75v I'd also suggest a 2s3p set up. Can you loosen one string on the flat roof and see what difference it makes at say 30°. It would be handy to be able to optimise the angle of the pannels for summer and winter sun.

2 hours ago, plonkster said:

So the MPPTs in the Infini-super are rubbish

Another thing to remember, we used ICC to monitor the usage/production and although its not precise measurement , but rather calculations made from info received from the inverter, it pointed to about 135 watt self consumption per unit at worst. For the 2 units in parallel, we could not account for between 200 and 300 watts at any given time. Inefficiency, losses, whatever the case were, up to 300watt that wasn't accounted for.  

300w over a 24h period is 7.2kwh which means approx 1.5kw of pannels just to run the inverters self consumption. Something to ponder when shopping for inverters.

Hi 

I have a Axpert 5KW x 2 with 12 x 330w 72.s connected to one inverter in 3S4P and 4 x 220ah AGM's

Installed myself and don't know if this is compatible setup or not ....will appreciate any advice i can get... am i over on panel specs or not...?

Also what is the best software to monitor this system..? 

 

Regards  Ron

9 hours ago, plonkster said:

Voltronic units start to derate above 135V.

130 V, I believe.

Quote

And the 15° angle is also a little suboptimal for this time of year.

Sigh! I missed that. That could account for most if not all the the deficit. With a 15° roof, I'd be tempted to use tilt frames to get the total tilt to at least (latitude + 5°). That's not good for summer, but in summer you usually have more solar energy than you need.

5 hours ago, Ron-45 said:

Axpert 5KW x 2 with 12 x 330w 72.s connected to one inverter in 3S4P and 4 x 220ah AGM's ...  don't know if this is compatible setup or not

As we've been saying, 3S of 72-cell panels is not recommended for 145 V Axperts. There is the possibility of derating (hence wasted PV power) and even equipment failure in the colder weather. Use 3S of 60-cell, or 2S of 72-cell, unless you are in an area that never gets below about 5°C.

5 hours ago, Ron-45 said:

Also what is the best software to monitor this system..? 

The consensus is that ICC is the best, even though it's not free, and you need a Pi to run it on.

23 hours ago, TommieWol said:

Thanks guys, the panels are installed on a flat roof with about a 15 degree north facing angle. No shadows over it for 90% of the day, and lastly, in Johannesburg

I’m not 100% sure of the cables, from what i can see on it is some german made 6mm (could be 8, writing on it is a bit hard to read) but looks closer to 6.

Not sure if it matters but the battery is a 4.8kw lithium connected to the mecer inverter

 

15 degrees from horizontal is too low, even for Johannesburg in mid summer. 

Here is a handy calculator for angle (from vertical) http://www.solarelectricityhandbook.com/solar-angle-calculator.html

This doesn't mean you are not running into the MPPT efficiency issue also, but I'd fix this first.

 

 

 

I like to use this simulator:

http://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#PVP

Enter your location (i.e. Johannesburg), enter your PV power and solar panel type. Enter mounting angle and direction (180 degrees for SA to point North).

Click on the "hourly data", select the start and end year and you get a nice text file showing your likely solar output for every hour in the chosen year (assuming perfect sky).

Seems to agree with what I get with my system very closely. Play with angles to see what gives. You can also allow it to choose best angles and direction for your location. For Joburg it seems to think about 31 degrees is best with about 10 degrees east of true north.

29 minutes ago, The Bulldog said:

I like to use this simulator:

http://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#PVP

Enter your location (i.e. Johannesburg), enter your PV power and solar panel type. Enter mounting angle and direction (180 degrees for SA to point North).

Click on the "hourly data", select the start and end year and you get a nice text file showing your likely solar output for every hour in the chosen year (assuming perfect sky).

Seems to agree with what I get with my system very closely. Play with angles to see what gives. You can also allow it to choose best angles and direction for your location. For Joburg it seems to think about 31 degrees is best with about 10 degrees east of true north.

Thanks, that is a great resource.  I have bookmarked it.