UPDATE: I have found that noon is more like 1315 (I don't have an almanac to work out merpas exactly) so time to go Flat is still 1145 based on least dip in amps but time to go to West after that is 1445 for a three hour Flat time mid-day.
I figured it must be time to raise the tilt angle a month after soltice, but this was a disaster. It turned out that raising the tilt angle at the high end made the whole panel sort of swing around to the right when tilted East so that it was optimum for later in the day and lost a bunch of earlier AH.
So adjusting the tilt by 8 degrees a month is only for a fixed tilted up panel facing South
I lowered it back down. It seems that to find the optimum orientation of my contraption for each month would take a whole bunch of computer assisted work that is not going to happen!
It also means that my special support with the post in the middle that can be raised and lowered is not required and a simple fixed stand would do instead.
It has stood up to high winds and otherwise is mechanically good, half way through this five month seasonal camping episode and nobody has climbed up there and stolen the thing while we were away either
Like the guy said when passing the tenth floor after falling off a twenty storey building, "So far so good!"
With this set-up I was able to run a test of flat vs tilted, which has been a matter of dispute lately, and also to compare with my results from "tracking" which features both tilting up and sideways.
I found that my contraption is not able to tilt sideways enough for earliest max morning and late evening, but his only costs me about 3 AH/day, so it has in practical terms only three positions, East, Noon, and West. It happens that the time to go from tilted East to Horizontal for "noon" (1pm) is 1145 and to tilt West 1415 with a 15 minute dip in amps in there, but perfection is not required. Makes camping life easy. (ie I could tilt it half way for say 30 minutes each side but AH gain is slight)
Anyway, 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)
So when away, I leave it tilted up in the 'Noon-flat' position.
It all depends on your daily AH usage and a million other things what is "worth" it, but perhaps you can use the above figures to decide whether an extra panel lying flat is worth it, to save you all the bother of parking just right for tilting or pointing or whatever the factors are for your rig.
Also there are time of year and latitude considerations. I used a solar guide's "optimum" tilt for the fixed South pointing case, where they want you to be lower than for noon to catch more shoulder hours light--the table shows how that worked out for the shoulder hours -flat vs tilted.
* This post was
edited 07/29/12 10:09am by BFL13 *
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Since my contraption gets decent results using only the three positions, those with tilting fixed panels could replicate the results by parking North-South and tilting East for morning, then at 1145 drop to flat for "noon" till 1415 or longer to sunset if the batteries are already charged up
If you need the extra amps in the afternoon then if your tilter is double action like some have, then tilt West at 1415.
Or if not double action, turn the rig (if a MH) 180 degrees and tilt up again till sundown and then turn it around again ready for morning.
Let me think... So, if the rig can not be turned, and it's not facing South, and climbing the ladder at noon is not desirable - then it wouldn't be productive tilting it permanently for a duration of day.
JiminDenver wrote: Thank you for posting the results. I would only track if we left our two panels on the ground. Mounted they could do tilted or flat.
Our 450 watts in two panels roughly work out like this with your numbers.
Using your numbers with expectation to better the Tracked 311 AmpH, it just leaves a person wondering; W?hy in the world would a RV'r take the time and effort to build, purchase, install, set-up, take down, risk falling off the roof or flying debris damage during wind and storm event,s with the tracker up.
Would it not be easier to add another single panel, equal or better, than the two panel output of 311 AmpH? It just baffles me. That is why many companies perform studies to decide whethere a product will actually cost more, than they can sell it for. In this case, the tracker is dead on arrival.
It's all about money. In mid 2011, I paid $450 for that 130w panel at a local dealer's. So I was determined to get the most out of it, which I did in this year 2012.
Now I found a different local dealer who has , eg 150w panels for $208!
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? - for those who don't want to bother of parking just right, but still want more output
