Panel Tilt angle ??

jrnymn7 wrote:
I'm thinking something along these lines:

http://www.homedepot.ca/product/magnetic-protractor-angle-locator/967209

That is pretty much what I have attached to my set-square. You set it on the panel and read the angle. Works great. Or you can just wait till high noon with no clouds just then and play with the tilt until it shows the rated panel Isc. That's your angle for high noon.

You need to know where South is too. It is where the sun is at 180 True, which is also at pretty much its "high noon" altitude. "Noon" on your clock is what it would be in the middle of your time zone, so if you are not there then noon is earlier or later--if you are west of the middle it is later. So where we camp in the summer it turns out that "noon" is more like at 12 after 1.

red31 wrote:


note that oct 7 is almost directly acress from mar 5 and how SLOWLY the declination changes from nov to feb

Nicely done, red31.

RJ needs to go back to the portable trailer aiming hitch unit and 190 watts of solar panel. Aiming problems solved.

I'm thinking something along these lines:

http://www.homedepot.ca/product/magnetic-protractor-angle-locator/967209

Salvo wrote:
Interesting, some 8 years ago I designed my winter tilt for Quartzsite (Lat = 33.43 degrees).

There's a few different methods to calculate tilt angle. Some very simple (for winter):

1. latitude + 15 deg = 48 deg
2. 0.9 * latitude + 29 deg = 59 deg

I use a more complicated calculation and got 56 deg.

The tilt angle for high noon anywhere is the same calculation as finding your latitude from your noon sight. People have been doing that for thousands of years, using various gizmos to measure the sun's altitude above the horizon at high noon.

It is mostly about the Declination that day, which changes about 8 degrees a month going up and down over a six month period, changing about 23.5 degrees every three months. EDIT however it is not linear as is shown above--good post showing that!! :)

That 15 degrees you see a lot of for this, is just a sort of middle point chosen for Declination between 23.5 and zero. 15 degrees is approx two months worth (linear--but it's not linear) so it would be for around mid- May or mid- July in summer so it fits as a good number for many people's RVing "season"

note that oct 7 is almost directly acress from mar 5 and how SLOWLY the declination changes from nov to feb

Interesting, some 8 years ago I designed my winter tilt for Quartzsite (Lat = 33.43 degrees).

There's a few different methods to calculate tilt angle. Some very simple (for winter):

1. latitude + 15 deg = 48 deg
2. 0.9 * latitude + 29 deg = 59 deg

I use a more complicated calculation and got 56 deg.

jrnymn7 wrote:
What do you guys use for fixing the angle? Level and angle finder, cardboard cut-outs, trig, or what?

I have an angle of the dangle thing on a set-square from years ago, but somebody posted the other day you can do it with your cell phone.

With the slope of the RV roof it can be tricky with no level horizontal, so some kind of gravity gizmo is easier.

Bill T wrote:
Humor me guys, I do not have solar yet but I am hoping to have one in the real near future. I will be getting a portable system since I camp mostly in the southeast, lots of trees.

Now to my comment considering the subject. Why not adjust the panel angle for the highest voltage reading? I understand there are premium times of day for the best performance, say noon time, set the angle at noon and then the performance would average out between daylight and evening. Just curious.

Yes you can pick the best angle at any moment by aiming it and watch for highest Voc and Isc, but that is not how it works for highest daily AH haul.

EG in the summer the sun goes around more than 180 degrees so it can get behind the tilted up panel facing South. To beat that, you pick an angle lower than what is best for high noon to get more time with more amps in the shoulder hours. See that link above on "optimum tilt"

The best thing is to keep the panel aimed at the sun all day, but that is not practical. You can move the panel three times a day and do almost as well. At dusk, aim it SE for next morning, then S mid-morning, then SW mid afternoon. Good enough.

To get a bit more with those three moves, have two tilt angles. Lower for mid-day and higher for SE and SW.

If you have trees on one side and open on the other, you might do better if using a fixed panel to aim it in the middle of your open sky spot and set the tilt for in there. That tilt would be higher than if aimed South. (The sun being lower in there at the open mid-point).

What do you guys use for fixing the angle? Level and angle finder, cardboard cut-outs, trig, or what?