HiTech wrote:
Last reading of the day. Almost made 17 - Watts Up says 16.996 amp hours for the day. I am not sure how much drop there is between today and the 21st, but being a sinusoid that is asymptotically approaching the minimum day length, I am going to assume the difference is tiny if I do not get any more full sun days for the experiment.
Jim
Thank you for reporting the 75%. That should be the worst case. I believe it is not practical for you to tilt as you would indeed need to construct framing at some additional cost.
You are correct about the day-to-day variance being smaller at the solstices. If you look at this
Solar tilt calculator, you will see that the winter season is the longest season measured in days, or 137 days. In spring/fall the angle sweeps more rapidly day-to-day and the days between tilt dates is shorter.
The calculator was developed, not by me - I wish, for a once per season adjustment. The Winter season is longer because there is less variance in sun angle. This is all explained in the macslab documents, I merely extracted from their docs. It considers seasonal insolation factors and will get you close enough on any given day.
Step 3 is where I got the 60%. I added step 3 to give an estimate of the penalty of not tilting and another aid in designing a system. It is a simple cosine of the tilt angel. Your 75% of Isc beats the estimate. Those panels are really nice. I will perform the same test soon. I have both types of cells, amorphous and mono, and a Turnigy for measuring.
HTH;
John
