Hello, this week I had a solar system installed with 16 panels and a Xantrex GT2.8-AU inverter. I have two Ground Mount frames with 8 Panels on each, setup at 30degrees and pointing north. The panels make up for 3.12kw. It was also explained that in real working environment I shouldn't expect more then 80% efficency from the 195watt SolarFun Panels, which would mean 2496watts @ 80%

Day one was overcast but the Inverter was reading 2500watts at it's peek.
Day two was overcast but the clouds were thin, was getting 2850watts at it's peek
Day three was cloudy but with clear patches max reading was 2200watts
Day four was a perfect day, but the inverter only showed 2300watts at its peek

Today is day 5, it's 10am and the power has been climbing slowly. At 9am it was showing 2000watts, 10am 2100watts.

Can anyone think of a reason why in direct sunlight with no clouds with panels facing north and at almost the correct angle that I didn't get 2500watts or higher. The installer told me the panels I have work at their best when the sun is with-in 20 degrees from it's center axis, and I think that should cover the 10am to 2pm mark if I am not wrong. The outside temp is 21c at the moment, the panels look clean, no bird poo or dust apears to be on them.

The Inverter is under the house and to save me jogging up and down the stairs all day I setup my laptop and webcam so I can keep an eye on it all day, I havn't learned enough yet to connect the inverter directly to a PC yet. So for now a webcam helps. Incase your interested in seeing it http://123.243.171.114:29000 I don't expect the webcam to be online for days on end, so if that link doesn't work then I most likely turned it off.

I also added a small 8mb video showing the Watts reading on the inverter, a quick glance in the sky to show the cloud cover and then how the panels are mounted incase it helps to understand why a few days later I can no longer get full power from the inverter. http://www.skozzyonline.com/video/Solar.wmv (no audio and low bitrate to keep the size small)

I not an expert by any means but have heard that new panel will put out high wattage for the first few days to weeks, then settle into there rated output at current temp. Your higher readings on partial cloudy days could be what is called cloud edge effect. Cloud edge acts like a prism and concentrates the solar energy for very short periods. If you watch your output just as the panels come out of shade then you will see the spike in output then settle back as you get clear sky. Also, keep in mind that the GT2.8 will limit its output, actually limits it's max rated wattage input. My GT3.8 has a max DC in of 4050 watts, yours will have a similar rating for your inverter. Down load the SGT-View from this site, the Zantrex inverters have a RS232 output, may need to get a RS232 to USB adapter for your computer. Works great. I have mine logging to file every 30 seconds and the display gives you lots of information on what the inverter is doing. Either make or get someone to put the connectors on a com cable for you and you can run to just about any place you want to set up pc.

Solar Guppy did a fantastic job on inproving on the viewer for the GT inverters.

Thanks for your reply. I was curious about the effects with clouds, cause I found with a slight cloud cover the sun looked more intence as it was bordering on the edge of a cloud.

I found a RS232 to USB adapter at MSY for $9, I am about to go pick it up. I also downloaded the Viewer program. I just hope the adapter is available at my local shop.

Moments ago I gave the panels a hose down, there was a fine dust layer over them as well as muddy hand prints I guess from the installers. Across all most of the panels the hose down gave me 100 watts more. Hose wasn't long enough to cover them all. I might give them a good wash, the day it was installed was a day after a big rain and my yard is mostly mud and the installers were covered in crap by the end of the day.

As panels bake in the sun, their power drops. A shot of water to chill them down will boost the power, but just till they warm up. And the thermal shock of cold water vs. hot panels is not always good.
Wait till a crisp, cold sunny winter day, they will really crank out power then.

Cause the panels are on frames in the yard and not on a roof they get lots of good airflow around them. At the peek of the day they are warm to the touch but not hot, I could comfortably keep my hands on them. I also went to bunnings and bought a window cleaner with extendable handle, from the ground I can reach and clean the lower two rows, the upper two rows I need a longer handle or a ladder. So I gave them a wipe down but didn't notice much improvement, guess the hosing off I gave them earlier lifted the fine layer of dust that was on them.

Today is an overcast day in Brisbane and the could cover is changing from thin to thick and power readings are low to be expected, so today is a writeoff for experimenting with tweeking the direction and angle of the panels. Even though I have them facing north and at 30 degrees, I get shade from the house nextdoor (well one of their trees), so at 2pm onwards I get very little power. So I was thinking of finding the golden point between 8am and 2pm when the panels are in the sun all day. I was thinking that cause the morning sun is lower I might change the angle from 30 degrees to 40 degrees and try that for a few days.

We had two days in a row with no clouds, both days collected 12.5+kwh. So with the direction and angle tweek I will see if I can beat that figure.

I also went to the computer shop to get the RS232-USB adaptor and it wasn't in stock. They put it on order but have to wait a week. What other place have people got theirs from, I would guess Ebay for one.

I got one from ebay - Digi Edgeport 8-port USB Serial Converter

They come on the surplus market often

search edgeport usb

used- condition unknown, but I got a working one, and they are built sturdy

I did see one, but the product description was poor. I will still wait on the RS232-USB adaptor from MSY, so far it's taking a long time to get.

For now, my laptop and webcam are working well, I put a LED light in front of the inverter and it made a big difference to how clear the screen is.