Advertising a system as 4kWp?

[dansk]

bingo!

 

[sambotc]

Personally disagree and I think it was probably exceeded earlier this year. Irradiance 1000w/m2 module temp of 25 and air mass of 1.5. Not sure of the air mass that time of year but the temp was fairly low and the sun was belting out down here.

Admittedly it won't happen very often, but i'm sure the STC is achievable, if it was set at 1500w/m2 then it would be a different story.

 

[Gavin A]

don't get me wrong, it will happen sometimes, but usually only for relatively brief periods as the panels will warm up in 1000W/m2 of sunlight unless there's a howling gale, or the air temperature is seriously cold.

Usually when it's cold the sun is at a lower angle in the sky, so for most roof mounted systems they're not peak.

Actually peak outputs tend to be found on clear bright breezy days in March / October when the air temperature is still relatively low, but the sun at mid day is relatively perpendicular to many arrays.

but over the entire year, it's only for a negligible amount of time that they would operate above 3.68kW AC output even if they weren't limited.

 

[screwdriver]

Are we also forgetting that a 16 amp capped inverter could output over 4kw with high local grid voltage and under 3.68 with a low local grid voltage , explain that one in your advertising literature!!!!

 

[langstroth2]

don't get me wrong, it will happen sometimes, but usually only for relatively brief periods as the panels will warm up in 1000W/m2 of sunlight unless there's a howling gale, or the air temperature is seriously cold.​

Funny you say that, today is the first time (since install Sep last year) I've seen my 4kWp system output getting to just over 4kw for brief periods - exactly because the sun is constantly going in and out behind clouds, and there's a very strong wind which is keeping the panels cool I think.

As you say in constant sunlight with little breeze it's more like 3400W ish.

I was aware of the expected output largely from reading forums such as this one, but you do see a number of posters on forums querying why their output never seems to get close to the array size.

​

 

[Gavin A]

Are we also forgetting that a 16 amp capped inverter could output over 4kw with high local grid voltage and under 3.68 with a low local grid voltage , explain that one in your advertising literature!!!!

not if they wanted to comply with G83 regs, where the nominal voltage of 230W applies - as Power-One discovered when they had to change their 16amp limit inverters to also be capped at 3680W AC output.