Solar Controllers--Don't be a Sucker! :(

Salvo wrote:
Here's some data on a solar panel I assembled over 10 years ago. There are 3 plots of solar short circuit current:

1. Panel perpendicular to sun
2. Panel flat on ground
3. Calculated sine of solar elevation

The x-axis is time in hours. x = 0 is when measurements are started, not associated with real time. y-axis is normalized current.

The flat plot never reaches y = 1 because the sun does not rise perpendicular to panel at that time of year (Oct. 18).

The last 3 measurements of the perpendicular plot shows how atmospheric dispersion kills solar power. Starting 1.5 hrs before sunset, solar drastically falls off.



Sal

Confirmed by my "tracking" results here (see table below)
IE, early morning or late evening, amps fell even when panel pointed.:


--At 49 degrees 24 min N, on 16-18 May with rare blue sky all day to take the measurements with Trimetric shunt on solar panel only, I got these figures for a single 130w panel rated at 8.2 amps at 25 C (test temp was 15C so got more max amps -to 8.3/ 8.4)

A. Flat on roof no camber-(used bubble level)- 56AH/day

B. Tilted up 25 degrees pointing South- 70AH/day

C. "Tracking"- (25 degrees up and East/Flat/West sideways) 90AH/day

A table of some results ( faked in mirror afternoon/morning results either side of 1300 (noon) when clouds happened or I missed a reading. Solar wake-up was 0600 finished at 2030 behind trees)

Time, Flat , Tilted, Tracking- Amps

0700- 1.0, 0.6, 3.7
0800- 2.0, 1.7, 5.7
0900- 3.6, 3.6, 7.3
1000- 5.1, 6.2, 8.1
1100- 6.3, 6.8, 8.2
1200- 6.9, 7.7, 7.7
1300- 7.2, 8.3, 8.3
1400- 7.1, 7.7, 7.7
1500- 6.4, 6.9, 8.1
1600- 5.0, 6.6, 8.1
1700- 3.9, 5.4, 7.3
1800- 2.0, 3.3, 5.7
1900- 1.0, 1.7, 3.7

Dips either side of 1300 due to not moving the tracker except three times a day (at dark, 1145, 1445)