How much should my system genarate?

[Big Al]

Hi. I'm new to solar so I may be expecting more that I've been told. I have just had a 2.2kW/h system installed and even on the most sunny day I won't get to 1.9kW/h.
The System is: 12x 180 watt 35 volt panels and a Xantrex GT2.8 inverter about 15 meters from the cells.
I was wondering if anyone has a similar system and whether is putting out about the same.

[russ]

Hi Big Al, Welcome to Solar Panel Talk!

You would need to mention the area and insolation plus ambient temperature for the guys to really comment but it seems you are doing well.

The 2.2 kW system rating is under lab conditions - not much to do with reality except that the conditions are standard which everyone testing can follow.

1.9 kW is 86% of the factory rating - good

Russ

[Jason]

Welcome Big Al! Glad to have you.

To fill out the location on your profile, click on the "forum actions" link at the top, then "edit profile" and scroll down a little to "location" and click save when you're finished.

[Big Al]

Hi Russ and thanks for your welcome.

I live on Gold Coast, Queensland, Australia where it's mostly sunny and warm. At this time of year the average daily temp is around 23 Degrees Celsius and the search for insolation took me to the following link:

http://www.gaisma.com/en/location/gold-coast.html

I guess the reason for my concerns started when I watched the installer measuring the total voltage under perfect conditions and where the reading should have been 420 volts (35 volts x 12 panels) it was showing only 380 volts or so. He said that it was a little low and was going to investigate further. My max daily power generation is around 13.5kW on a sunny day and between 5kW and 7kW on a cloudy day. Being new to all of this I just wanted to be sure not to expect close to 2.2kW even under perfect conditions.

All in all I'm very pleased with the system - it's great to see the meter box sending power back to the grid!

[russ]

@ Big Al, Mike or Sunking will most likely be along and they know better that I - looking forward to their comments.

Typically panel output is calculated at around 80% of name plate rating - panels are tested and rated at under perfect conditions and 1000 watts/m2 which is rarely seen and then only for period a few minutes.

[Sunking]

My max daily power generation is around 13.5kW on a sunny day and between 5kW and 7kW on a cloudy day.

Well then everthing is fine. Looking at your solar insolation in Octiber you are nearing your peak prodution months. Right now you are recieving 6 Sun Hors per day, and with that you should be generating 2200 watts x 6 hours x .8 = 10.6 Kwh. So you are are doing quite well.

[Mike90250]

80% for factory wattage is good. you are doing even better. (unless you have amphorus cells which will fade to label spec in a few months)

As panels heat up in the sun, their output voltage will drop. At dawn or dusk, you will see higher voltages, while the panels are still cool. Hopefully , your installer has taken that into account, and you will not fry your inverter from over-voltage on your first frosty/cold morning.

[Big Al]

Hi Sunking and Mike90250.

Thanks for putting my mind at ease. It good to know that the system is performing at it's best.

Mike the inverter should be fine as the maximum the panels can put out is 420v and the inverter is rated at 600v and we don't have too many cold mornings where we are. You were right about the cooler panels though. Today it was cloudy but when a sunny patch passed through, the inverter went up to 2388kW and then dropped back slowly after a few minutes to 1956kW - wow!

Thanks again to you all for you advise - it is much appreciated.
Al.

[russ]

In mixed clouds and sunshine periods you will get some strange numbers.

I have a Davis weather station and record hourly readings where I see those.

Russ