Tilting Solar panels makes a big difference!

[DAS26miles]

I had 2 100 watt Renogy solar panels on my roof and they seem to only have an output of 3.4 amps each. I added a third panel and now the max is around 10 amps this time of the year for the 3 panels. I also have a Renogy Solar100 watt portable suitcase which has a max output of 5.5 amps. I laid it flat and it only added 3.7 amps but when I tilted it for max sun it rose up to 5.5 amps. I hope during the summer my max on the flat panels gets up to over 5 amps each.

[BFL13]

Mr Wiz could string that array up like a hammock N-S only with the North end higher. Hang a weight on the East side to tip it. Move the weight to the other side in the afternoon, after leaving the hammock flat mid-day. Hang it from an awning stanchion, side mirror, or door handle?

Frees the MH to be parked at any angle. Just the "hammock" needs to be N-S.

[BFL13]

With that shape of array, it can be difficult to set it up to twirl as well as be tilted, but there is another way to get the same effect that could be easy, depending on the whole situation.

Orient the array lengthwise N-S tilted up, and be able to flop it sideways or be flat. In the evening you flop it to the East, ready for morning. If high noon is 12, then from 11-1 have it flat, then flop it to the West.

I had a way of doing that in 2012 and it worked out great for AH haul. It would not need to be anything so complicated for Mr Wiz's situation. He needs a lightweight quick set-up and breakdown that won't blow away, and is easily stored in the MH, but that is not impossible.

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/26065604.cfm

[MrWizard]

Like this

Solar panel tracking kit

Most people would just purchase more panels, unless the roof was already covered

You need one for every panel, including the additional frame and mounts for the tracking hardware,

Cheaper and easier to just install more panels

Maybe a good idea if you have a small RV and one large panel

[MrWizard]

I use an awning a lot, but this one recently sustained damage
And needs to be replaced

If i could get a solar awning, i would love that

[DAS26miles]

maillemaker wrote:
I'm surprised someone has not invented a solar rack that mounts to the top of the RV that has built-in "leveling jacks" that automatically tilt the panels for you and track the son for optimal panel angle. Should also have a built-in auto-retraction/stowage system so that if it detects any movement of the RV it automatically stows itself so it won't get damaged.

Steve

Great idea!

[maillemaker]

I'm surprised someone has not invented a solar rack that mounts to the top of the RV that has built-in "leveling jacks" that automatically tilt the panels for you and track the son for optimal panel angle. Should also have a built-in auto-retraction/stowage system so that if it detects any movement of the RV it automatically stows itself so it won't get damaged.

Steve

[westend]

I am at 45 degrees North (central MN). I have my panel set at 56 degrees. Since I'm lazy, the panel stays at that angle through the Winter and into the Spring. This positioning is to gain Winter sun power and to allow for snow to shed so power is still available throughout the Winter. In the Summer, panel is positioned flat. My mounts actually tilt 4 ways but my storage situation is static, at present, so a tilt to the South maintains batteries well.

[BFL13]

"look at my shadow in the picture, they only need about 20 degrees of tilt to be 90 degrees to the sun"

You lose amps when off by only 10 degrees and it gets worse over that amount. It is really worth the bother to get the tilt about right.

If the correct tilt at high noon is 30 degrees (top up from flat) as stated, then the sun's altitude would be 60 degrees. That is quite high for January! As mentioned, if you are at 35N and Dec is 21S, your noon tilt would be 56, making the sun's altitude 90-56 = 34

You can check by waiting till noon and put your voltmeter or ammeter on the disconnected array and tilt it up and down watching the Isc or Voc change. The Voc will drop as soon as the sun hits the panel, so wait till after that settles if you just took out the panel from the dark.

If you know your latitude and declination you can get the correct high noon tilt. Declination tables are probably on line somewhere. Runs from near 23N to 23S so your tilt angle is always changing.

Whatever your North latitude in January, if you stay there the tilt will be more than that now and be reducing. It will be equal to your Lat on 21 March, then get even lower until 21 June. Then it goes back the other way for the next six months.

So if possible, arrange to be able to change your tilt over the next few months to be lower and lower till 21 June. Try to stay under ten degrees off as correct tilt changes. Pick a number and change it once a month would be good.

Optimum for all day AH haul is lower than for the correct high noon angle if the array is pointing South all day. Idea is to let the shoulder hours sun get on the panel better. If you only deploy the array mid-day, then tilt up nearer the high noon angle.

You lose amps when the sun is off by only a little. 10 degrees has a loss. The sun goes around at 15 degrees an hour, so you lose a lot by not being able to twirl it. Tilting is not so bad because there is much less angle it can be off optimum as the sun goes up and down.

If you did have a twirler, then the tilt for that is the other way for optimum. Now you want the tilt higher in the shoulder hours than at mid-day to be aimed at the lower sun.

EDIT--looking at photo, you must have the same concern about using the awning. Perhaps ? since that array is only 11 pounds? the whole tilting business could be solved by laying the array out on top of the awning! Set awning angle for proper tilt. (PT is always talking about having his awning made from solar cell material 🙂 )

[MrWizard]

the sun angle to the panels was a lot better than being flat on the roof

look at my shadow in the picture, they only need about 20 degrees of tilt to be 90 degrees to the sun

i have some ideas for tilt, like hanging the panels a little higher and letting the open compartment door be the prop behind the panels

i tried them leaning/tilted against the RV sitting on the ground, the breeze knocked them over, flat face down
this was 'ONLY' the first use test

they are NOT here to replace the generator, only to supplement it

yes i want efficient use, but i also do NOT want to picking them up all day long

[BFL13]

To get your value from that solar, you really need to tilt the array at an advantageous angle, not have it hanging straight down. In the photos it looks like needing to hold it up from the bottom somehow to get the desired tilt angle. Makes a big diff in AH haul.

--or set the bottom on the ground out a ways and hang it the top as shown from hooks lower down?

The optimum tilt changes with your latitude and the sun's declination over the year.

EG if you are at 35N and Dec is 21S like maybe around now, your high noon tilt would be 35 + 21 = 56 degrees. Lower that a bit for "optimum"

By 21 March when Dec is zero, your noon tilt will be 35 if you are still there in March. By 21 June when Dec is 23N, your noon tilt would be 35 - 23 = 12 degrees or almost flat for optimum. Note that Dec is N after 21 March till 21 Sep, so you now subtract Dec instead of add it to the Lat.

[MrWizard]

as promised Pix


Click For Full-Size Image.

Hanging on the side of the RV, i put the controller in the shade under the RV, i intend to lengthen the solar feed wire and shorten the battery charge wire


Click For Full-Size Image.

the got the suction cup hooks at the 99cents store
if they fail i will look for better ones online

i looked at the picture, saw the stretched D-ring
and replace it with a key ring

have to go to the hardware store and get a few key-rings
the D-rings are NOT strong enough for the appox 11# weight

11# is light for 200 watts, the size is about right for 200w
but the D-rings are TOO Small

any way preliminary feeling is, i like it, the controller even has (2) lithium battery settings, not that i need that, but thought i would put the info out there

[MrWizard]

It has arrived, just got back from the mail run
Have it hooked up and facing the sun
Battery was at 12.8 on the controller when i connected it
Charging at 13.7v , 4.8 amps, with no loads except parasitic, fridge controls etc..
Will see what happens when i turn on the Max air fan, and the laptop

Pictures soon

Edit
Now at 14.1v , 5.4 amps

1:15 PM
14.0v 7.5 amps laptop on

A step in the right direction
keeping the batteries at 14v all afternoon will definitely increase battery life and reduce my fuel consumption

[Almot]

SoundGuy wrote:

Almot wrote:
100W solar will harvest ~30AH on a good day.

I often use under 35AH a day.

Nice patchwork, but you've left the piece out. It goes like this: "I often use under 35AH a day. But my 500W flat array will get me those 35AH 99% of time, including days with low overcast and some rain. "

If somebody's particular expectations are to rely on solar on good days only - this is too indeterminate subject.

[MrWizard]

YEP ! i agree
thats why there will be roof Solar
just not right now

after the safari is gone, i can use some of that money for the solar on this one