2.9kw from 2.4kw pvs?

[Gabriël]

hi, i have pvs capable of generating 2440watt yet yesterday the icc program indicated i had a max pv production of 2929watt.

any ideas as to what is that all about?

God bless

g

[SilverNodashi]

In simply, layman's terms, you had the perfect conditions for good solar production. We have, about 1Kw /square meter of solar radiation to harvest. Solar panels are, generally, developed to delver 305W (in your case) at 25degrees Celsius, with 1Kw UV/sqm. If there's more UV it could produce more energy, but that doesn't happen very often. I often see that overshoot on a nice crisp, and cold day.

 

Yesterday was such a nice cold day with no clouds in the sky and in your case when the sun was at the right angle it could have "over produced" as you have seen.

Edited November 5, 2018 by SilverNodashi

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25 minutes ago, gabriel said:

hi, i have pvs capable of generating 2440watt yet yesterday the icc program indicated i had a max pv production of 2929watt.

That's about 20% over. I've seen it many times. I've done a record 2200W with a 1860Wp array.

[SilverNodashi]

12 minutes ago, plonkster said:

That's about 20% over. I've seen it many times. I've done a record 2200W with a 1860Wp array.

Which is also why you need to upscale your fuses by at least 20% ;) 

[Riaanh]

40 minutes ago, gabriel said:

i had a max pv production of 2929watt.

Also keep in mind that the "max PV" you are referring to have not necessarily been continuous. As Plonkster noted, Even I had very good results on clear but COLD days. The maximum  for "day" many times from my experience happens on good day, and with what I call edge trigger. On a clear day, with one or more lost clouds floating around once that cloud edge gets to the PV "sight", you see a huge spike and again on the other edge when the cloud leaves. Typical in the range you an Plonky re referring to.

 

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1 hour ago, Riaanh said:

have not necessarily been continuous

Yup. And because fuses don't generally blow the moment you go over, even if you didn't oversize them by 20% you can often get away with it at least for a while :-) Then one day you'll have one of those "wolkie" days as I sometimes call them, just multiple small clouds hanging around all day doing nothing except flare sunlight, and repeated power spikes on top of good production will finally push it over.

At this very moment I am running 10A fuses on a string that I've seen doing 9.5A on those really bright days. I really need to find some 12A fuses...

[Antony]

1 hour ago, plonkster said:

That's about 20% over. I've seen it many times. I've done a record 2200W with a 1860Wp array.

But this is still below your 3KVA Victron MultiGrid MAX Watt input?

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Just now, Antony said:

But this is still below your 3KVA Victron MultiGrid MAX Watt input?

Uuuhm, not sure how to answer this. The Multigrid doesn't have a built-in MPPT (the EasySolar does) so there isn't really a relation between the size of the PV array and the size of the inverter. If you want to get technical, then yes, the array is a tad small, if I made it bigger I could run the inverter at peak power for larger parts of the day.

With the old 1600VA I had, the inverter ran at peak power from 11AM to 3PM every day... and I still had more PV than I could convert into AC, so if I wanted to mazimise my production for the day I had to make sure I had space in the batteries, which means I had to start discharging them no later than 6AM :-)

[Gabriël]

2 hours ago, SilverNodashi said:

Which is also why you need to upscale your fuses by at least 20%

which ones?

[SilverNodashi]

Just now, gabriel said:

which ones?

your PV fuses.

[Gabriël]

3 minutes ago, SilverNodashi said:

your PV fuses

would this fuse between the axpert and pvs suffice?

[Chris Hobson]

1 hour ago, plonkster said:

At this very moment I am running 10A fuses on a string that I've seen doing 9.5A on those really bright days. I really need to find some 12A fuses..

Aaargh I have 2 boxes in the toolbox. I could have delivered them in person.

[Chris Hobson]

36 minutes ago, gabriel said:

would this fuse between the axpert and pvs suffice?

Too high in my opinion. You might have a small braai going before that fuse will blow.

[Gabriël]

1 minute ago, Chris Hobson said:

small braai going before that fuse will blow.

hence the fire extinguishers...hahaha, now but seriously, would you go down to 20amp?

[Chris Hobson]

I need to qualify that if that is to protect individual strings it is too high. If it is for the home run between combiner box and inverter then it is good for two strings.

[SilverNodashi]

4 minutes ago, Chris Hobson said:

Too high in my opinion. You might have a small braai going before that fuse will blow.

His strings runs at 17.5A. 20A might blow too quick, so this would do.

[Chris Hobson]

Panels run at about 9 Amps so per string 9 *1.25 =11.25A make it 12A. I have used 15A where multiple strings will still cause it to blow.

[Gabriël]

2 minutes ago, Chris Hobson said:

I need to qualify that

that is the final fuse between the 8 pvs and the axpert, i dont know whats on the roof, i know there are 4 strings and 8 pvs

[Chris Hobson]

5 minutes ago, gabriel said:

that is the final fuse between the 8 pvs and the axpert, i dont know whats on the roof, i know there are 4 strings and 8 pvs

Gabriel I would get someone up on your roof and check. If you have 4 strings then I would expect that fuse to have blown just under normal operation (8.33A * 4 = 33A).

If you have 2 strings of 4 then you would have the quoted Isc of 17.46 A but a Voc max of 179.6V well clear of the Axpert's 145VDC.

The only thing that makes sense is 3 strings of 3 your fuse wouldn't blow but neither would your Axpert. But nine panels is pretty easily discernible from eight panels so I have no doubt you have eight panels. My brain is doing flick-flacks trying to see how the could be configured and not blow either you inverter or the fuse above.

[Gabriël]

3 hours ago, Chris Hobson said:

I would get someone up on your roof

that someone was me  - quite gusty today....

so i cant figure it out  and took a photo of the top 4 pvs wiring, attached -  you guys can send me up again with instructions, i'll try and follow them

     

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That suggests two strings of 4 each. And those taped-up connections... that is the stuff of nightmares. Please tell me it is at least soldered under there, and that is is heatshrinked and not just taped up. Also, please tell me these were at least cable-tied to something before you pulled them out...

[Gabriël]

1 hour ago, plonkster said:

please tell me 

Well, as stated months ago, the installer was fly by night  - no solder no cable ties...

[Gabriel_2018]

10 hours ago, gabriel said:

hi, i have pvs capable of generating 2440watt yet yesterday the icc program indicated i had a max pv production of 2929watt.

any ideas as to what is that all about?

God bless

g

I suppose there was some clouds. 

What happens is called cloud edge effect. Solar radiation can rise 1400-1500 w/m2.

 

[Gabriel_2018]

2 hours ago, plonkster said:

 

That suggests two strings of 4 each. And those taped-up connections... that is the stuff of nightmares. Please tell me it is at least soldered under there, and that is is heatshrinked and not just taped up. Also, please tell me these were at least cable-tied to something before you pulled them out...

OMG! Also, It could be dangerous in cold days for the 145 Vo limit.

[Gabriel_2018]

If @gabriel has lithium battery can make four strings because he doesnt need go to high charge voltage.