Solar PV Peak Output?

jamesingram

Hobbo2006 wrote: »

Most I've seen so far is 2.5kW. I'll have to check the inverter as that keeps a record. Today was nice 13.06kWh. The generation graph was like an equilateral triangle, slightly squashed at the top. Slight shading for an hour whilst the sun goes behind a tree. Guess that would be worse when the leaves come out.

Just wondering who would notice if I put another 5 on the east side.

i live close to you and our 4.32kW of panels (SE). gen. 18.77kWh today
max single point output approx 3kW
11 and 5 on each orientation/string sounds a strange setup , what was the reasoning behind this from the installers ?

EricMears

Martyn1981 wrote: »

Hello Wensleydale. First let me caveat this with you need to speak to an expert / your installer, but I'm 99% certain that that model is a single MPPT. It can take 2 strings, but they would need to be identical in all aspects size, orientation and roof angle.

You really need an inverter with dual MPPT which effectively treats both roofs as separate entities. I suspect with your 5 + 6 set up, the inverter is ignoring the lower voltage string (the 5 panel string). Even if both roofs had 5 or 6 panels each, the different orientations wouldn't do too well either.

I think you need to have a chat with your installer.

Anybody else? Do you think I've got that right?

Mart.

When Wensleydale has had a look at the Sunny Explorer page I mentioned, he should be able to see if there are two sets of data or only one.

With panels facing in two different directions, a dual string inverter is surely essential. If there is only one then inverter will always be limited by whichever side is doing worst at the time.

Martyn1981

EricMears wrote: »

When Wensleydale has had a look at the Sunny Explorer page I mentioned, he should be able to see if there are two sets of data or only one.

With panels facing in two different directions, a dual string inverter is surely essential. If there is only one then inverter will always be limited by whichever side is doing worst at the time.

Eric, it might be worse than that, help me out here if I'm confusing myself, but regardless of which string is producing more watts, won't the higher voltage of the 6 panel string always over-ride the 5 panel? Effectively taking the 5 panel out, regardless of whether or not it's producing more watts at any given part of the day?

I'm wondering if Wensleydale would be better of with two inverters (if a suitable small dual MPPT isn't available). Maybe a SB1200 on the 5 string and a SB1300TL on the 6 string. I've got a SB1200 but like it's bigger brother the 1700, it's not very efficient, and is quite noisy, compared to the TL models.

Mart.

PS: This is all getting very techy for a Friday night!

PPS: Sorry Wensleydale if I'm depressing you.

M.

wensleydale

Martyn1981 wrote: »

Eric, it might be worse than that, help me out here if I'm confusing myself, but regardless of which string is producing more watts, won't the higher voltage of the 6 panel string always over-ride the 5 panel? Effectively taking the 5 panel out, regardless of whether or not it's producing more watts at any given part of the day?

I'm wondering if Wensleydale would be better of with two inverters (if a suitable small dual MPPT isn't available). Maybe a SB1200 on the 5 string and a SB1300TL on the 6 string. I've got a SB1200 but like it's bigger brother the 1700, it's not very efficient, and is quite noisy, compared to the TL models.

Mart.

PS: This is all getting very techy for a Friday night!

PPS: Sorry Wensleydale if I'm depressing you.

M.

Not depressed yet, as I witheld some of the final payment as I wasnt certain it was as it should be.
Will check it tomorrow.

grumpyoldsteve

Hobbo2006 wrote: »

Firstly, Happy Cloudless Day Everyone! (if you live near me that is). I'm sure today is going to be the best so far.

I'll admit that before my solar panel installation I knew nothing about them whatsoever. I had no preconceptions at all. I was just concerned with whether the panels would return roughly what the SAP calculations said they would, and therefore the FIT payouts would be as quoted.

After installation I'm starting to find out more and ask questions. One of which is about the peak output of the system. I see that although we have a 4kW system the peak output is rarely above 2kW. Presumably the close we get to Jun 21st the better that will get. Just wondering what peak output's other installations get?

Would anyone be able to work out what the peak output would be of the following system?

11 x 250w panels facing West, 5 x 250w panels facing East, Aurora Power One 3.6 outdoor inverter

Is there anyone with the perfect installation? Due South, 4kW, optimum angle, no shading that could post their peak output figures?

I know that the invertor can take up to 4.25kW, according to Aurora's own manual so is there room for 5/6 more panels to go on the East side of the roof? (there is physical room for this).

My guess is that it's not as simple as this but maybe, just maybe it is! :cheesy:

My 2.45 kWp system is regularly achieving 2kWp on these sunny spring days in sunny Somerset. 14kWh today total, the highest since commissioning last September. It is on a South facing roof at about 37 degrees pitch. On average I am getting 25% more than the http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php simulation
The Fronius 3KW inverter actually shows the maximum ever output as 2.74kWp - not sure how that happened.

Kernel_Sanders

EricMears wrote: »

I've (briefly) considered that too ! Suspect it would need planning permission as mirrors would need to be fitted well away from the permitted developmnt zone but more importantly they'd be subject to enormous wind stress.

Even if you could have motorised mirrors with a computer adjusting their angle, there is still the problem of partial shading. They wouldn't be allowed anyway, because birds would fly into them.
Now, a gigantic magnifying glass suspended over your array......that would be a far better idea!

wensleydale

Hi all,
I've been out this morning and looked at the software readings but to be honest I am not sure what I need to look for- I've taken screen grabs of what I think are the right pages and saved them on the links below- can anyone offer any suggestions?

http://www.londonweddingdisco.co.uk/screengrab.xlsx

http://www.londonweddingdisco.co.uk/screengrab2.xlsx

Thanks
Rich

EricMears

wensleydale wrote: »

Hi all,
I've been out this morning and looked at the software readings but to be honest I am not sure what I need to look for- I've taken screen grabs of what I think are the right pages and saved them on the links below- can anyone offer any suggestions?

http://www.londonweddingdisco.co.uk/screengrab.xlsx

http://www.londonweddingdisco.co.uk/screengrab2.xlsx

Thanks
Rich

It suggests to me that you have but a single 'string'.

As discussed yesterday, output of 'good' panels (i.e. those facing sun) will be held down by the 'bad' ones.

I'll try & post my own screen grab in a minute but basic difference is that it has a "current 002" section after "current001" but before "voltage001" (& of course voltage2 & power2 sections)

(later)

see : http://www.khormaksarschool.org.uk/SolarPanels/ScreenDump.htm
or basic image is at : http://www.khormaksarschool.org.uk/SolarPanels/ScreenDump.jpg

I've only fully expanded the current001 current002 sections else picture would get too big to view on screen all at once.

In case anyone notices appalling output from a S facing 4kwhp system, I should explain that it's very misty here this morning.

wensleydale

EricMears wrote: »

It suggests to me that you have but a single 'string'.

As discussed yesterday, output of 'good' panels (i.e. those facing sun) will be held down by the 'bad' ones.

I'll try & post my own screen grab in a minute but basic difference is that it has a "current 002" section after "current001" but before "voltage001" (& of course voltage2 & power2 sections)

(later)

see : http://www.khormaksarschool.org.uk/SolarPanels/ScreenDump.htm
or basic image is at : http://www.khormaksarschool.org.uk/SolarPanels/ScreenDump.jpg

I've only fully expanded the current001 current002 sections else picture would get too big to view on screen all at once.

In case anyone notices appalling output from a S facing 4kwhp system, I should explain that it's very misty here this morning.

Thanks for this- without sounding like too much of a novice how can I confirm the single/dual string- follow the cables and look for what?
There are 2 inputs into the inverter but I guess I need to see how they are connected to the panels?

Martyn1981

wensleydale wrote: »

Thanks for this- without sounding like too much of a novice how can I confirm the single/dual string- follow the cables and look for what?
There are 2 inputs into the inverter but I guess I need to see how they are connected to the panels?

Rich, Eric clearly understands this better than me, and I think he's confirmed that it must be a single string:

1. Your details don't list a second voltage, as Eric pointed out.
2. The voltage of 343V would suggest 1 string as many panels will be around 30V each (very rough statement so please don't quote me on that), so 11 * 30V = 330V so definitely in the same ballpark.
3. Each string would have 2 cables 1 'in' and 1 'out' so 2 strings would be 4 cables. Sorry for misleading you by introducing the issue of strings.

I'll do some quick googling on dual MPPT inverters.

Back soon.

Mart.