What are you currently generating ?

[FB.]

My Fronius IG30 Plus with10 Sanyo HIT 250W panels picked 3499W!! How about that!

http://img441.imageshack.us/img441/6...0419134952.jpg

Isn't the sun much stronger in Australia?

 

[Scobo]

Isn't the sun much stronger in Australia?

Doh !!!

 

[valet]

Yee..probably is stronger. But overperformance by 1kw is it normal?

 

[FB.]

Yee..probably is stronger. But overperformance by 1kw is it normal?

I've not heard of that kind of outperformance, but I don't know many Aussies. :wink5:

My panels are:
In England, where the sun is weaker.
Chinese-made low-mid-range, so very likely to be noticeably inferior to Sanyo (I reckon about 10% less than similar Sanyo systems in my area).
55 degrees off the optimum facing.
A couple of months away from the longest days/strongest sun.

....and despite all those disadvantages, my panels can reach 270W output even though they are nominally 250W.

 

[FB.]

I've not heard of that kind of outperformance, but I don't know many Aussies. :wink5:

My panels are:
In England, where the sun is weaker.
Chinese-made low-mid-range, so very likely to be noticeably inferior to Sanyo (I reckon about 10% less than similar Sanyo systems in my area).
55 degrees off the optimum facing.
A couple of months away from the longest days/strongest sun.

....and despite all those disadvantages, my panels can reach 270W output even though they are nominally 250W.

Sorry, to clarify......

270W per panel - 1.9kW from a string of 7x 250W and 2.1kW from a string of 8x 250W.

 

[yellowvanman]

How can they run at +40% above their rated output? Perhaps 10% or so but surely not 40%. If they really are running at +40% then that means they were operating at an efficiency of nearly 31%. All the best.

It all depends on the irradiance levels! The 250W wattage of the panels are for 1000W/m2, if it was a really bright sunny day maybe the irradiance levels peaked at 1400W/m2! giving 40% more power!

 

[Del Boy]

You'd probably need irradiance levels of 1400W/m2, and it to be quite a cool day too! I'm amazed the inverter allowed that though... 10% above it's max DC input before inefficiencies. Good to know it's possible.

@valet: Whereabouts in Oz are you? I'm guessing near the Tropic of Capricorn.

 

[valet]

Thank you for replies.....I am in Darwin. So is hot and humid. Inverter is 3kw with transformer is it normal to have on display 3499w?

 

[SolarCity]

Apparently so. I've not had much experience of foreign systems but I do know of a system in the Caribbean which is showing similarly impressive figures.

 

[valet]

Anyones system overperforms in this hot/sunny few days?

 

[scottliv]

Now that it has got alot hotter here, the output on my sanyo panels has actually dropped. There does seem to be a high haze, but the increased temperature has probably dropped the panel output.

 

[methley]

Likewise, my Sanyos are down in power too. Previously on sunny cold days they were easily hitting +10% whereas in the last couple of days they have peaked at -5%.

 

[danesol]

Likewise, my Sanyos are down in power too. Previously on sunny cold days they were easily hitting +10% whereas in the last couple of days they have peaked at -5%.

Its not down to heat alone, its down to the haze you cant see IMO, today looks different here so the results will speak for themselves later......

 

[danesol]

Just checked my reading......... think its going to be an excellent production day today...

At 12noon ;

DC read 2669watts ( 5.68 amps @ 471vdc )

AC read 2624watts (10.48amps )

45watt loss = 0.016% loss ??

I believe Sanyo's in the North West will do extremely well today..................

 

[FB.]

Its not down to heat alone, its down to the haze you cant see IMO, today looks different here so the results will speak for themselves later......

Yes, due to the unprecedencted rain and saturated ground, we've had a lot of mist, fog and haze in the last couple of months which, I believe, has resulted in my system never managing to reach its full potential on any day.
On days without haze, there were numerous clouds dotted around which periodically covered the sun, therefore lowering the day's generation below its potential.
As a result of this heavy haze (or clouds), 4kWp systems - even the South-facing Sanyo's - in this area have been struggling to achieve more than low-20's kWh in a day.

Today has been one of the better days so far this year (looks like it'll be the first day of dawn-to-dusk clear sky since 01st April), but still a brownish-grey haze noticeable and much hotter than any day so far this year, so the solar panels are far from ideal conditions.
My system has been peaking today around 90% of capacity, but was peaking around 105% during brief sunny spells a month or so ago.

3.75kWp, 3.6 inverter, facing between ESE and SE, 40-degrees slope.

Readings:
Time: 12.34pm, outdoor temperature = 25degrees (peak power was a couple of hours ago, around 10.30-11am)

Inverter internal temperature: 44.9'C (Power One Aurora indoor model)
Temperature of room in which it is located: 23.75'C (to nearest 0.25'C)

Electricity produced so far today: 16.3kWh
Power out: 2.705kW
Voltage out: 242.9V
Current out: 11.1A

Array-1 (8x250Wp)
217.1V, 7.2A, 1561W (=195W per panel)

Array-2 (7x250Wp)
188.7V, 7.1A, 1336W (=191W per panel)

Power coming into inverter: 2.897kW
Power going out of inverter: 2.705kW
Inverter efficiency: 93.4%

 

[FB.]

Here is a comparison with the first time it reached full power output, during a brief sunny spell on an otherwise cloudy day in early April:

Detailed statistics 11.17am:
(the numbers don't quite add up because they were slightly changing from second to second as I copied them down)


Power output: 3.66kW
Voltage output: 246.6
Amps output: 14.7
Volts array-1: 247.4
Volts array-2: 201.2
Amps array-1: 8.1
Amps array-2: 9.4
Watts array-1: 2055 (8 panels = 256.9W/panel)
Watts array-2: 1843 (7 panels = 263.3W/panel)

Ambient temperature: 13'C, breezy.

The room which houses the inverter was probably about 16'C at the time.

Inverter efficiency:
Power in: 3.898kW
Power out: 3.66kW
Efficiency: 93.9%

 

[EXC]

Hello All
I have been taking readings from my 3.84 kW 16 X Suntech 240w MC panels ,SW facing about 35deg in West Sussex PVsystem for the last six months ,
I had the system installed 2nd Dec . First 1/4 FIT total was 277kWh second 1/4 sent last week was 1372 (produced 1095 last 1/4)
I have installed a' Parsons Switch' so now have free hot water when producing over 1.5kW ( takes most of the day to heat the immersion to 70deg C)

 

[MicraShed]

OK, Im puzzled (not difficult)

After reading my handbook I decided to crawl into the loft and find out what my peak power generated was today and since the system went live... And for 10x 250w panels I was surprised:-
Today

2769W

Lifetime

2850W

Peak AC voltage has been 251v.

Any ideas, I thought that I would be lucky to get 2400W peak

 

[Earthstore]

Panel performance is given under STC ( standard test conditions), so they all rated at a certain temperature etc, with our current weather conditions being sunshine and showers, the rain will cool the panels way below the STC, so when the sun pops out they will perform higher than rated just for a while.
I hope this helps.

 

[MicraShed]

Thank you, yes that makes sense.
Is there any truth in the fact(!) that the panels are under rated when new so that as they degrade over time they will still be theoretially putting out 90% of their maximum when they get to 20 years old? Or is that just wishful thinking?

 

[Eco Deal]

I like to point out STC (standard test conditions ) are as follows

25 oC
1000 wM2 (watts meter squared)
1.5 Air mass

but some sales guys will tell you a right load of cods wholup

''our panel only need 3 hours sunlight''
''our panels are the best ever ''
''our panels work off moon light''

 

[FB.]

Thank you, yes that makes sense.
Is there any truth in the fact(!) that the panels are under rated when new so that as they degrade over time they will still be theoretially putting out 90% of their maximum when they get to 20 years old? Or is that just wishful thinking?

I don't think panels are under-rated. They are correctly rated at the standard test conditions, and are often sorted into 0~+5W power bands in the factory (e.g. panels "flash-tested" at 240-244.9W go into the 240W pallets).

As for long-term power output: I think the panels will hold up fairly well.
I have been told by someone who studies such things that even older solar panels haven't lost as much performance as would be expected - even 20yr old early-1990's-manufactured solar panels still perform within about 10% of their original power. A few fail completely or almost completely, while many get externally tatty, but most hold up surprisingly well in terms of output despite often looking in poor condition.
They reckoned that the worst loss in power output is early in the panel life, as dodgy cells fail within a year or two, and as a balance of dirt builds on the glass. I think they said about a 2-3% power reduction each year for the first year or two is common, but after that the power reduction is virtually nil each year (less than 0.25% drop per year on average from years 3-20), except when the panels get really old and the seals get weathered, then the whole panel can malfunction due to large amounts of damp getting in.
The guy reckoned that about half of all solar panels ought to still be functioning at more than 80% of nominal output even when they are 35 years old.

 

[MicraShed]

except when the panels get really old and the seals get weathered, then the whole panel can malfunction due to large amounts of damp getting in.

Reassuring, though I popped out this morning and noticed dirt (bird muck I think ) on a couple of panels. So that left me praying for rain!

What happens when a panel fails though in say 5 or 10 years? Can it be replaced or would it be impossible if that panel was no longer available as it would not be possible to "mix and match".
Would I be looking at replacing the whole lot if a couple went duff.

Im being pessimistic here assuming that my installer wont be around in 10 years time and my guarantee wont be worth the paper its printed on (just like double glazing guarantees I have for the porch, it may be guaranteed for 15 years, but as the company went bust not long ago its now worthless).

One of the reasons I paid on the credit card, so that I can try and invoke section 75 if need be. It probably wont work, but I can hope!

 

[FB.]

Reassuring, though I popped out this morning and noticed dirt (bird muck I think ) on a couple of panels. So that left me praying for rain!

What happens when a panel fails though in say 5 or 10 years? Can it be replaced or would it be impossible if that panel was no longer available as it would not be possible to "mix and match".
Would I be looking at replacing the whole lot if a couple went duff.

Im being pessimistic here assuming that my installer wont be around in 10 years time and my guarantee wont be worth the paper its printed on (just like double glazing guarantees I have for the porch, it may be guaranteed for 15 years, but as the company went bust not long ago its now worthless).

One of the reasons I paid on the credit card, so that I can try and invoke section 75 if need be. It probably wont work, but I can hope!

I reckon in several years time there will be a big market in spares for the recently-installed solar arrays, as the systems age and faults develop. Only a tiny number of the panels/inverters installed in the last year need to fail in order to create quite a business opportunity.

If one panel failed, I suspect that you'd either have to:

1.
If the string voltage is high enough to disconnect that dud panel and still meet minimum inverter startup voltage, then carry on with one less panel but leave the dud one on the roof for cosmetic purposes.

2.
If you have two strings, cannibalise one string to make the other work.

3.
Replace all your panels, and sell them on the secondhand market which will probably be booming by that time as other people with the same dilemma desperately seek a certain make/model of panel are are prepared to pay £££ to keep their array looking neat.

 

[SolarCity]

To be honest, I don't think there will be much of a market for 2nd hand panels. They'll be as cheap as a tramps sock and they'll very rarely fail.

 

[Gavin A]

fwiw, IMO the main failure point in the panels electrically will be the bypass diodes, which I believe should usually fail closed, so that effectively it just removed the bypass functionality, though I suppose some will fail in such a way that they bypass that circuit.

either way, replacing a bypass diode ought to be pretty simple (once the panel's off), so I can see this being a worthwhile sideline / business in 10 years time once the warranties are up.

Incidentally, I reckon it's likely that this is an area the cheapest manufacturers will be scrimping on, but have no specific info on that, just my hunch. One day I might get bored enough to destruction test the bypass diodes from a high end and cheapo panel....

 

[FB.]

fwiw, IMO the main failure point in the panels electrically will be the bypass diodes,....

Yes, I think you're probably right.
I think bypass diodes will be/have been skimped on.

I would also expect that the more a bypass diode is used, the greater the likelihood of its premature failure. I therefore expect arrays with shading issues to be among the most likely to have problems.

Thinking about it a bit further, I wonder whether a panel with failed bypass would cause similar symptoms to the peak-power-drop-off which was extensively reported last year.
If a panel with failed bypass is in shade while the others in the string are in sun, it could cause a big drop in production as a result of the failed bypass diodes not allowing the power to flow past the shaded panel.

 

[SibertSolar]

Diode failure is extremely uncommon to be honest, unless the manufacturer used a very inferior product in the first place. In my experience with junction boxes, the diodes are typically very over-specified and, as a rule, are not particularly expensive anyway. New package design shottky diodes, typically with very low volt-drop, are hitting the market although tried and tested axial diodes from the likes of Panjit and ST are very mainstream. Remember also that the IEC tests require each individual diode to be rated for all potential failures associated with the whole module. Given that most crystalline modules have 3 or more sub-strings, each protected by a single bypass diode, you could deduce that the diodes are 3x over-specified.

Diodes can fail, especially where the thermal dynamics of the junction box don't allow enough heat dissipation and "thermal runaway" occurs but it is extremely rare. I have only ever come across this once under lab test conditions - and that was one diode of three that appeared to have an inherent issue that caused it to go short-circuit then open circuit. I've never yet come across a field-based diode failure but, of course, it could happen....