MichaelK
Solar Wizard
You may have seen some of my previous posts where I mentioned the deals I've been getting on returned grid-tie panels. My latest purchase were four 245W Astronergy panels (55$ each, 220 total cash) that supposedly were one year old, and repossessed off of someone's roof? I knew that I really needed to qualify the panels to make sure they were performing anywhere close to what they were supposed to make.
I have positioned this array facing due west, because my goal was more power in the late afternoon. All my other arrays for the cabin are in a south facing orientation, and start getting heavy shading around 4:30-5:00pm. For my test, I ran my wellpump as a load, which is ~2000W-AC, and significantly higher than what the array should be producing. This west-facing array has the four Astronergys wired in series for 120VDC, feeding into my Midnight 200 controller. Here's the power output of the array at hourly intervals, read off the face of the Midnight controller.
2:00pm 800W
3:00pm 850W
4:00pm 920W
5:00pm 870W
I was astounded at the 4pm production. With the panels nameplate-rated for 980W, I was getting 920W in real-world conditions. That works out to about ~94% output. This is in warmish, 80F degree weather, with the panels warm to the touch. The best I've seen with other brand-new brands (Renogy, YingLi) was ~87%. The fact that this was at 4pm instead of noon is even better! Holding a pipe in front of a panel at 4pm, I saw the panel was almost exactly perpendicular to the sun at that time. I am very, very pleased with this purchase. Now I'll be able to run a 8000BTU air conditioner late in the day.
I have positioned this array facing due west, because my goal was more power in the late afternoon. All my other arrays for the cabin are in a south facing orientation, and start getting heavy shading around 4:30-5:00pm. For my test, I ran my wellpump as a load, which is ~2000W-AC, and significantly higher than what the array should be producing. This west-facing array has the four Astronergys wired in series for 120VDC, feeding into my Midnight 200 controller. Here's the power output of the array at hourly intervals, read off the face of the Midnight controller.
2:00pm 800W
3:00pm 850W
4:00pm 920W
5:00pm 870W
I was astounded at the 4pm production. With the panels nameplate-rated for 980W, I was getting 920W in real-world conditions. That works out to about ~94% output. This is in warmish, 80F degree weather, with the panels warm to the touch. The best I've seen with other brand-new brands (Renogy, YingLi) was ~87%. The fact that this was at 4pm instead of noon is even better! Holding a pipe in front of a panel at 4pm, I saw the panel was almost exactly perpendicular to the sun at that time. I am very, very pleased with this purchase. Now I'll be able to run a 8000BTU air conditioner late in the day.
