AnswerID: 275557 Submitted: Friday, Dec 07, 2007 at 21:24
Member - John and Val W (ACT)
replied:
Hi Michael,
My technique for optimum angle - Adjust so that the panel throws the biggest shadow, i.e. intercepts the maximum amount of sunlight. The angle is not very critical. (A mathematician would point out that we are dealing with a sine curve, and that's pretty close to it's maximum over a fair angular range.)
Wiring - I use 2 panels. Simply wired in parallel. You won't exceed the 10 amps which (I think) your controller is rated at.
I find moving panels to follow the sun is worth doing a few times per day, certainly not as frequently as every hour.
An interesting fact that I'd overlooked until recently -
My camp uses about 35 Ah per day. A 60W panel will provide about 3.5 A in good sunlight, that's about 20 Ah per day, which is some help. With my 130Ah storage (and using only 2/3 of that in order to preserve battery life), I can remain stationary with the 60W panel for about 5 days instead of 3. If I could harvest 40 Ah per day I'd have ample to last until the sun stops shining. I've added another 85W panel, and now have more electricity than I need. The two turn in about 9 amps in full sunlight, over 50 Ah per day, so aiming them accurately at the sun is not an issue - I can afford to be suboptimal.
(I expect an argument about the above statement that a 60W panel only supplies about 3.5 Amps. Fact is it's a fact! Solar panels are rated at their highest power output, which occurs at about 17.5V. Hence a 60W panel provides about 3.5A x 17.5V = about 60W. But for battery charging we can only use up to about 14.4V, not the full 17.5. The 3.5 Amps is available, but because of the reduced voltage, the 60W is not.)
I'd suggest that you best approach is to keep the two panels together, both looking approximately at the sun from around 9am to 3pm - simply facing north and angled for biggest shadow should do it. It's important to use heavy gauge cable since you will be moving a few amps and can't afford much voltage drop.
HTH
John
| J and V
"Not everything that can be counted counts, and not everything that counts can be counted."
- Albert Einstein
|
Reply 3 of 3
FollowupID: 539318 Submitted:
Friday, Dec 07, 2007 at 22:54
Gronk posted:
Ahh, the joy of having too much power !!!!!!!
If I could get 2 x 85W panels for $500, then solar would be the go for me !!!!!
Thumbs UpThanks 0
FollowUp 1 of 3
FollowupID: 539320 Submitted:
Friday, Dec 07, 2007 at 23:16
Member - michael H (NSW) posted:
Hi John,
Exactly the
feedback I was after I might try and see if I can put a plug in the back of the first panel to piggy back the second panel then I have a choice of taking one or two panels using the single regulator and maybe padlocking the two together to slow the honest thief down ha ha.
Thanks again very helpful info
Michael
Thumbs UpThanks 0
FollowUp 2 of 3
FollowupID: 539331 Submitted:
Saturday, Dec 08, 2007 at 06:42
Member - John and Val W (ACT) posted:
Hi Michael,
Your piggyback proposal is exactly what I've used. Mine slide into slots on the (custom) roof rack, one above the other.
On the road the top one is exposed to the sun and feeds into the lower one which is then connected via a controller to the battery. In camp the two stand side by side and both harvest sunlight. Both have handles on one end. Pass a heavy steel cable through the handles and padlock to the vehicle (trailer in your case) and you have a little security, though as you say, only ok for an honest thief!
The thing I didn't say too well above is that one 60W panel gives an extra day or two, while two 60W panels give permanent independence while ever the sun shines! It's a major step which is obvious, but I only discovered with hindsight!
John
| J and V
"Not everything that can be counted counts, and not everything that counts can be counted."
- Albert Einstein
|
Thumbs UpThanks 0
FollowUp 3 of 3
