Solar panel output
I had a weekend at home! It was great. I achieved stuff and I collected data....what, you expected otherwise? :)
Since I was home pretty much all weekend, I checked the output from the inverter hooked up to our solar panels every time I remembered (and when I wasn't generating sawdust).
I was a bit surprised to see it cut off pretty hard at 1650W, since we have a 2.1kW system, but K tells me the installer dude told her it would - apparently the panels lose efficiency as they heat up, which seems like a remarkably contrary thing for a solar panel to do. What we need is cold sunny days...
I also got thrown by the alignment of the curve - somehow I expected it to max out at around 3-4pm...you know, when the temperature's hottest. But of course a North-facing panel1 is going to work best when the sun's North...like at midday. Duh. In fact it'll probably tail off faster in the afternoon in summer as the ambient heat builds up.
Raw data:
SaturdaySunday
08:00900
08:20950
08:451320
09:301430
10:081480
10:401620
11:3016401650
11:531645
12:201645
13:001635
14:001575
14:301460
15:3011001155
16:30685
17:00450
17:20320
18:3030
1 Actually our panels are oriented very slightly - ~5° W - off-axis from North, since they're mounted on a West-facing roof of that pitch. So I'd expect to see a peak just after midday, although this may be offset by the rising heat.
Since I was home pretty much all weekend, I checked the output from the inverter hooked up to our solar panels every time I remembered (and when I wasn't generating sawdust).
I was a bit surprised to see it cut off pretty hard at 1650W, since we have a 2.1kW system, but K tells me the installer dude told her it would - apparently the panels lose efficiency as they heat up, which seems like a remarkably contrary thing for a solar panel to do. What we need is cold sunny days...
I also got thrown by the alignment of the curve - somehow I expected it to max out at around 3-4pm...you know, when the temperature's hottest. But of course a North-facing panel1 is going to work best when the sun's North...like at midday. Duh. In fact it'll probably tail off faster in the afternoon in summer as the ambient heat builds up.
Raw data:
SaturdaySunday
08:00900
08:20950
08:451320
09:301430
10:081480
10:401620
11:3016401650
11:531645
12:201645
13:001635
14:001575
14:301460
15:3011001155
16:30685
17:00450
17:20320
18:3030
1 Actually our panels are oriented very slightly - ~5° W - off-axis from North, since they're mounted on a West-facing roof of that pitch. So I'd expect to see a peak just after midday, although this may be offset by the rising heat.