Solar panels

Submitted: Sunday, Nov 15, 2009 at 14:56

ThreadID: 73766 Views:4565 Replies:7 FollowUps:12

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Solar Power

This article covers every aspect of solar and its design and installation in RVs (camper trailers, caravans and motor homes). It shows how much power solar panels really produce,

Member - Daryl N (NSW)

Ok
Because my enquiry about solar panels last week sparked a lot of discussion(some of which went beyond my technical knowledge) I thought I would share my thoughts on where we have got too.
From what I can gather most of the better panels that we looked at are all Mono-crystalline cells with a maximum voltage of about 17.2 Volts that give an operating current of between 5 to 7 Amps depending on how many Watts the panel puts out
We used the solar calculators that are on the ExplorOz website to determine what amount of Watts we needed (I can recommend both these calculators) and what we thought our future needs would be.
Currently we have one 45L Engel fridge and several lights. Our thoughts at the moment are that we may expand to a second fridge. We also have limited space so size is an issue for us. Consequently we have decided to look for a solar setup that will give 120 Watts and is compact. To do this we are looking at a setup that has 3 40 Watt panels and should collapse to a size roughly 55 x 55 x 10 cm
Cheers
Daz

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Reply By: Mandrake's Solar Power- Sunday, Nov 15, 2009 at 16:27

Sunday, Nov 15, 2009 at 16:27

Gooday Daryl - I'll take a quick moment here before I get slimed again ...LOL

I don't think you'll find a 3 panels setup - You'll probably have to get 2 with 2 panel sets and work your wiring out around that sort of setup..

Now I'm going into the bunker !! LOL

Rgds

Mandrake

AnswerID: 391296

Follow Up By: Maîneÿ . . .- Monday, Nov 16, 2009 at 09:59

Monday, Nov 16, 2009 at 09:59

hey, get outa my bunker :-))

Maîneÿ . . .

FollowupID: 659233

Reply By: Member - Phantom (WA) - Sunday, Nov 15, 2009 at 16:51

Sunday, Nov 15, 2009 at 16:51

Hi Daryl,
I have just purchased last week a 3 x 40 (120w) solar panles that folds up like a suitcase and comes with a canvas bag. I bought it via Ebay from Australian Direct.
Haven't tried it yet but it is about $600 cheaper than the normal 2 x 60 w jobbies and has a 25 year warranty. Made in Oz and apears god quality.

Steve

AnswerID: 391299

Follow Up By: Maîneÿ . . .- Monday, Nov 16, 2009 at 10:24

Monday, Nov 16, 2009 at 10:24

yeah, always thought "god" could be an Aussie too

From their website: The 120 watt Split Fold comes fully equipped with an *INBUILT* 20 Amp Solar Regulator which regulates the panels to approx 14.1Volts.

My thoughts:
- Will never get anywhere near 20 Amps from the 120Watt system
- The 14.1v is low compared to more efficient regulators which give >14.7v
- Hope the regulator is *N0T* attached onto one of the panels :-)

Maîneÿ . . .

FollowupID: 659235

Follow Up By: Member - Oldplodder (QLD) - Monday, Nov 16, 2009 at 16:53

Monday, Nov 16, 2009 at 16:53

Mainey,

I am setting up a solar panel at the moment too.

Interested in your comment that the regulator should not be mounted on the back of the panel, but with my very limited knowledge, don't understand the dos and don'ts.

Is it a heat problem, or is it a voltage drop problem, or something else?

FollowupID: 659280

Follow Up By: Maîneÿ . . .- Monday, Nov 16, 2009 at 17:25

Monday, Nov 16, 2009 at 17:25

The solar regulator regulates the power going to the battery, if it's placed at the panel it has no loss associated at that point, but every chance the battery will not receive the full power available because of voltage loss in the long cable to the battery.

However, when the regulator is placed at the battery end it's (most) probably already suffered a power loss with-in the cable by the time the power reaches the regulator and the power is then regulated at that point.

It will deliver a greater charge to the battery this way than when the regulator is on the panel allowing the regulated power to diminish with-in the cable on the way to the battery.

Maybe that's the reason it will only deliver 14.1 Volts
(although I think it's because it's not an efficient regulator anyway)

Maîneÿ . . .

FollowupID: 659288

Follow Up By: Member - Daryl N (NSW) - Monday, Nov 16, 2009 at 21:41

Monday, Nov 16, 2009 at 21:41

This is what makes these forums realy useful to lay people like myself.
If I understand you correctly most solar panels setups won't deliver what they promise because most have the regulators close to or attached to the panels and in most cases result in a reduction from 17 to 14 volts irrespective of the number of watts being produced.
If the regulator is located near to the battery as you suggest is there still a voltage drop? If so roughly how much?
Daz

FollowupID: 659329

Follow Up By: Maîneÿ . . .- Tuesday, Nov 17, 2009 at 22:58

Tuesday, Nov 17, 2009 at 22:58

Daryl,
no real smart solar supplier will give you the regulator attached to a panel, unless the panel sits beside the battery, they will tell you to fit the Solar regulator adjacent to the battery system.

In any long (extension) power cable there will always be a voltage drop when the cable is undersized, and most are.
When the regulator is near the panel, not the battery, the power is regulated for a lesser output and then that further reduces as the Voltage is further lost in the cable.
However when the solar reg is placed where it should be, beside the battery, it regulates whatever voltage it gets from the solar system, sending it to the battery beside it with no further voltage loss incurred.

Maîneÿ . . .

FollowupID: 659458

Reply By: DIO - Sunday, Nov 15, 2009 at 17:05

Sunday, Nov 15, 2009 at 17:05

What sort of batteries did you have in mind for the fridges and lights to connect to?

AnswerID: 391302

Reply By: RV Powerstream P/L - Sunday, Nov 15, 2009 at 17:36

Sunday, Nov 15, 2009 at 17:36

What part is made in Oz and especially if its $600 cheaper than 2 60W.

I have built triples for people and Mandrake could do the same you just reverse hinge the third panel.

Mandrake you can do it be inovative man.
Ian

AnswerID: 391304

Follow Up By: Mandrake's Solar Power- Sunday, Nov 15, 2009 at 18:00

Sunday, Nov 15, 2009 at 18:00

Ian ,

I am technologically handicapped when it comes to this sort of thing - as evidenced by the Tardis's Solar Rig that collapsed on the Oodnadatta track !!

However I did ask my daughter today to see if she can make

carry bags to suit 2 X 50watters !!

Maybe later LOL

Cheers

Mandrake ( reporting from the bunker )

FollowupID: 659166

Follow Up By: RV Powerstream P/L - Sunday, Nov 15, 2009 at 18:51

Sunday, Nov 15, 2009 at 18:51

Mandrake
We are all challenged in some way or another but you are having a go and all you need is a drill and pop riveter and some hinges and rivets and some 25MM ali angle for the legs that you can fit inside the frame so that the unit can fold without obstruction and your away.

If your daughter can make the bag get her to make the fold up and just dont tell anyone.

Ian

FollowupID: 659168

Follow Up By: dbish - Sunday, Nov 15, 2009 at 19:05

Sunday, Nov 15, 2009 at 19:05

Hi Mandrake Have a go its not hard to do what Ian said ive done the same with 4 X 20 Watt panells folds up quite compact. Cheers Daryl.

FollowupID: 659170

Follow Up By: Member - Lia H (SA) - Tuesday, Nov 17, 2009 at 22:02

Tuesday, Nov 17, 2009 at 22:02

Yeah go on Steve,

I've seen your work, you can do it!! :)

FollowupID: 659447

Reply By: Member - Daryl N (NSW) - Sunday, Nov 15, 2009 at 20:29

Sunday, Nov 15, 2009 at 20:29

I have a 105 a/h battery

AnswerID: 391327

Reply By: Member - Daryl N (NSW) - Sunday, Nov 15, 2009 at 20:36

Sunday, Nov 15, 2009 at 20:36

One of the problems I have found is that there is not a great deal of information on who makes what component of solar panels and where they come from. Most sellers just don't provide the information. I guess if and when I ring that information may become available. It has been one of my big frustrations

AnswerID: 391329

Follow Up By: Maîneÿ . . .- Monday, Nov 16, 2009 at 10:08

Monday, Nov 16, 2009 at 10:08

Maybe because they are Ummmm . . . made from elcheapo crap components?

Those who sell quality BRANDED named panels have no hassles with the panel performance in LOW LIGHT conditions, as you won't need their full capacity all the time, or even most of the time.

Maîneÿ . . .

FollowupID: 659234

Reply By: Member - Oldplodder (QLD) - Monday, Nov 16, 2009 at 16:59

Monday, Nov 16, 2009 at 16:59

While every one is talking panels, I notice in most pictures of setups that when the panels are not fixed, but placed out in the sun with a lead back to the battery, the panels tend to be placed portrait mode, not landscape mode, on the ground. Why? To me the panel is less stable this way if a breeze comes up.

Apologies for hijacking the original post.

AnswerID: 391408

Follow Up By: Maîneÿ . . .- Monday, Nov 16, 2009 at 17:07

Monday, Nov 16, 2009 at 17:07

John,
if I was standing a loose panel (or multiple panels) on the ground, I would definitely do it as you suggest, and for the same reasons too

Maîneÿ . . .

FollowupID: 659284