Solar Panels grid for RV battery

[kostianych]

I have 2 Coleman 40W 12V 7Amp solar panels.

How can I use them to charge my 12V deep cycle RV battery?

If I connect them parallel, I will have 12V with 40W and 14Amps, right?

What controller do I need? I have a 7AMP controller that came with the panel.

thanks
K

[4extreme]

You can get a bigger control panel and plug in multiple solar panels. Im in the process of doing the same thing. I've been looking on line. I can get 200w for around $450

[250mark1]

You will ever get 14 amps with 2 40 w panels
I have a 160 watt and 95 watt tied together on the roof of my teailer and never see much more than 8-10 amps mind you my 4 6 volts are usually charged back up to 100% by 700 am this time of year on sunny morning

[250mark1]

Pretty sure it was positive to positive negative to negative I did this in a weather tight junction box on the roof of my rv
And then Same to control panel (Should up grade wiring to Handle higher amps)
And battery

Place in red deer is selling 260 w panel/controller and wiring kits for 600
http://www.innovativesolar.ca/

[Junglefisher]

W = VA.
Watts = Volts x Amps.
40 = 14 (most solar panel produce 14-17V) x 2.8.
So 2.8 Amps.
Or if they are 7Amp, the will be producing around 100W.
The 7amp controller should handle two panels easily.

[Mountain Guy]

2 panels and 1 controller? Or did you get a controller with each panel?
So it all came as a kit?
Not sure exactly what you got going there... I assume if you got 1 controller with 2 panels that both panels will plug into the one controller.
in any event as already said you'll only get a little over 7 amps total with 2-40 watt panels

[Suzukisam]

Up here in Canada you will get 5.71 amps out of 80 watts of solar panel on a good day the voltage regulator controls voltage not amps. It has the capability of handling max 7 amps. That combination should work fine. Yes they are connected to the voltage regulator both positive's together and the two neg to each other. (Parallel)

[Jeron Kahyar]

Originally Posted by Junglefisher

W = VA.
Watts = Volts x Amps.
40 = 14 (most solar panel produce 14-17V) x 2.8.
So 2.8 Amps.
Or if they are 7Amp, the will be producing around 100W.
The 7amp controller should handle two panels easily.

The controller is likely rated for 7Amps @ 12V. So if you are pushing 14V in they will not handle 7A @ 14V (closer to 5.75A @ 14V).

Something smells awful fishy with the solar panels however.

40W / 12V = 3.33A

Not sure how they are calling them 40W/12V/7A solar panels. Sounds a little like marketing Hocus Pocus to me.

[Gary K]

Originally Posted by Jeron Kahyar

The controller is likely rated for 7Amps @ 12V. So if you are pushing 14V in they will not handle 7A @ 14V (closer to 5.75A @ 14V).

Something smells awful fishy with the solar panels however.

40W / 12V = 3.33A

Not sure how they are calling them 40W/12V/7A solar panels. Sounds a little like marketing Hocus Pocus to me.

i believe the panels are rated at 3.5 amp, and the controller is rated to 7.

[Marsha]

I have one of these
Maximum power output: 40 Watts and 2.3 Amps under ideal condition
and it comes with a 7 amp controller so you can link 2 panels together to get 4.6 amps Max under perfect conditions.

to use 2 panels
How many panels can I connect to my 7 Amp Solar Charge Controller?
You can connect up
to 105 Watts of Solar Power to the 7 Amp Solar Charge Controller. Panels should be
connected in parallel
–
positive to positive, negative to negative

[kostianych]

Originally Posted by Marsha

I have one of these
Maximum power output: 40 Watts and 2.3 Amps under ideal condition
and it comes with a 7 amp controller so you can link 2 panels together to get 4.6 amps Max under perfect conditions.

to use 2 panels
How many panels can I connect to my 7 Amp Solar Charge Controller?
You can connect up
to 105 Watts of Solar Power to the 7 Amp Solar Charge Controller. Panels should be
connected in parallel
–
positive to positive, negative to negative

thanks, this is what I figured out too
K

[Mountain Guy]

Originally Posted by Suzukisam

Up here in Canada you will get 5.71 amps out of 80 watts of solar panel on a good day the voltage regulator controls voltage not amps. It has the capability of handling max 7 amps. That combination should work fine. Yes they are connected to the voltage regulator both positive's together and the two neg to each other. (Parallel)

Well... I clipped my 80W panel and I was getting over 7A .

[birdee]

my 1oow panel was about 5.75amps on a very good day
so there is no way you would get 7 amps out of a 80watt panel
back of a 40 watt panel

https://www.topsolarpanel.com/wp-con...harger-0-6.jpg
and a 100watt panel

http://www.windynation.com/products/z_336_5_0.jpg

[mayuan]

What you are dealing with is a a solar panel that is rated @ 17.1V as a working voltage, the Amp rating for the circuit is 2.3A. This works out to be a 40W circuit, the 7A comes from the charge controller that comes with the system. Hook up the two panels in parallel and connect them to the controller that came with the system and then the controller connects to the battery.

[Mountain Guy]

Originally Posted by birdee

my 1oow panel was about 5.75amps on a very good day
so there is no way you would get 7 amps out of a 80watt panel
back of a 40 watt panel

https://www.topsolarpanel.com/wp-con...harger-0-6.jpg
and a 100watt panel

http://www.windynation.com/products/z_336_5_0.jpg

I guess my ammeter was lying to me then.

[KegRiver]

Originally Posted by Mountain Guy

I guess my ammeter was lying to me then.

Not necissarily.

Ratings are most often made under best case scenrios. What you get in the real world can very widely.

Smog can effect output, setup angle can effect output.

Not all panals are created equal, some are simply garbage.

To complicate matters further, meters used to read output can give inacurate results or can be read wrong.

In the end it doesn't really matter. If it works for you that's enough isn't it?

[KegRiver]

Originally Posted by birdee

my 1oow panel was about 5.75amps on a very good day
so there is no way you would get 7 amps out of a 80watt panel
back of a 40 watt panel

You do realize that it's illegal for manufacturers to make false claims.

If it's rated at 80 watts and 7 amps it should be able to do that under ideal conditions.

It's often said that the further north you go the less solar energy you get but that's not the whole story.

While it's true that you get less energy over a given time, it also depends a lot on time of year since during the middle of the summer you get more daylight hours then further south and that offsets the lower solar energy.

http://pages.mtu.edu/~raman/SilverI/..._latitude.html

There are just too many variables to make definitive statements about any installation without doing hands on testing.

[jip911]

Amps = watts divided by volts..
Most charge controllers put out 14.4-14.7 volts
80/14.4=5.6 amps
Add in everything from the panel to the wiring to the controller are not 100% efficient and you would be lucky to get anything over 90% or 5 amps...

J

[Mountain Guy]

Originally Posted by KegRiver

Not necissarily.

Ratings are most often made under best case scenrios. What you get in the real world can very widely.

Smog can effect output, setup angle can effect output.

Not all panals are created equal, some are simply garbage.

To complicate matters further, meters used to read output can give inacurate results or can be read wrong.

In the end it doesn't really matter. If it works for you that's enough isn't it?

Yes of course...
I was just commenting that , as you indicate what something is rated at doesn't always apply.
It was mentioned that you can't possibly get 7A out of a 80 W panel.
The fact is you get what you get under certain conditions. I was pulling around 7.3A out of a 80W panel..
Many variables, and I also wouldn't trust the the cheap little controller that comes with the panel .