Solar Power Wattage

Submitted: Thursday, May 27, 2004 at 14:08
ThreadID: 13211 Views:2237 Replies:7 FollowUps:5
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G'Day All,
I'm a dummy when it comes to this stuff so hopefully someone can provide some info. I can't find the info I want in the archives or internet.

1. I'm looking at getting solar power with the new Avan, it comes with an optional 50 amp solar panel. My question is, is a 50 amp panel big enough to recharge the vans battery during the day, when lights are on at night, music playing, etc. Looking at sitting in one place for 1-3 days then moving on.
I know 2 x 50 amp panels would be better, but is that an overkill / waste of money etc.

2. How do you wire up a third battery (van battery) to be charged by vehicle when on the move. Is it from the vehicles second battery. If so, does another isolator have to be installed between the second and third battery etc etc

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Reply By: Member - Murray C (VIC) - Thursday, May 27, 2004 at 14:21

Thursday, May 27, 2004 at 14:21
G'day Shawn, I have been through a similar exercise recently of determining power consumption and the means of regenerating it. If you message me with your web address I will send you a copy of an "excel" spreadsheet that I used to begin to solve the problem.
Regards, Murray
AnswerID: 60437

Reply By: Peter McGuckian - Thursday, May 27, 2004 at 14:25

Thursday, May 27, 2004 at 14:25

You will find lots of useful advice at campertrailers. You might also look for the manula on campertrailer/caravan electrics by Collyn Rivers. 50W is plenty for running just lights.

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AnswerID: 60438

Follow Up By: Rosscoe - Thursday, May 27, 2004 at 14:48

Thursday, May 27, 2004 at 14:48
Might be worth a search on Google for the Avan Club(s). I remember reading an article on wiring your car for trailers that was primarily written for Avan owners although it was pretty generic as well.
FollowupID: 322020

Reply By: Rosscoe - Thursday, May 27, 2004 at 14:41

Thursday, May 27, 2004 at 14:41

The first thing is to work out how much power you expect to consume. The arithmetic for this exercise is not difficult but a bit hard to explain on this forum.
You then need to get a "practical" specification for the actual power the solar panel(s) in question will produce Although rated at 50, 60 or 70 watt they apparently, in practice, do not produce at 100% of their respective ratings.
To be self sufficient for say three days you need to be able to replace the current you use in any one day by the solar panel/regulator plus a bit for losses.
There is a good book on the subject wriiten by Collyn Rivers. I think it's called "Solar that Really Works"

AnswerID: 60440

Reply By: Member - Peter (York) - Thursday, May 27, 2004 at 15:15

Thursday, May 27, 2004 at 15:15
Hope this helps as a guide
10 watts = .5amps
20 =1.1 Size BP solar panel .424mm x 502mm
40 =2.3
60 =3.5 1110mm x 502mm
80 =4.55
125 =7.1 1510mm x 674mm

work out what amps each unit drawers this is usually in the manual or on the plug of the unit you are running and this will give you a good idea of what you need

COST BIAS boating supplies in all states

10 watt $164 20 watt $264 40 watt $389

60 watt $569 80 watt $729 125 watt $1089

PLUS you will need a regulator if there is a chance of over charging you battery
approx cost $80.00 at same supplier
hope this is of use to you
AnswerID: 60444

Reply By: Magnus - Thursday, May 27, 2004 at 16:59

Thursday, May 27, 2004 at 16:59
Hi Shawn,

I have used a 20 watt panel for 3 years to charge up a 27 amp hour battery set up to run lights of up to 3 amp current draw of a night. Longest stay on battery power was 10 days with no problems.

If all you are running are lights and you are in an van (not a 25 foot motor home where you might need plenty og light to find your way from one end to the other) then 50 watt should be ample to replace your nightly usage.

Wolud strongly suggest you wire in a good ammeter calinbrated up to 5 amps so you can read the draw. You will need to go to Jaycar or similar to get one. The ammeters sold in auto store do not give a fine enough read out.

That way you can monitor your current draw at night.

Also you should have a voltmeter installed to tell battery voltage. If the van does not come with one fitted, then a visit to Jaycar will see you fixed.

Lastly buy a good battery charger of around 2-4 amp output so you can put the rig on charge before you leave home. Better to leave home with a fully charged battery than not. If you go out with obe only 80% say then you will have problems as the panel may not bring your battery up enough after the first night.

Saw that just last week. Brand new off road rig. Flat battery after first day. Camper and wife, experienced too, hadn't charged it up before leaving home. Wasn't me, but fellow camper had a generator so charged him up enough so they could stay the week provided they didn't run any lights at night.!!

And, yes, Solar panels do not put out the rated amperage except under ideal laboratory conditions. So, most people over solar rather than under solar.

Having said that, lights only, up to 3 amps draw, 50 watts should be ok.

Have fun

PS I assume you will also carry an emergency gas light. I use a small Gaz model with disposable cartridges. Takes up not much more space than a roll of toilet paper but when you need it!! Like Toilet paper, can't do without it.!!!!.


AnswerID: 60464

Follow Up By: V8troopie - Thursday, May 27, 2004 at 23:58

Thursday, May 27, 2004 at 23:58
Magnus, I second your suggestion re installing an Amp meter but, while you're at it, wire it in so that the solar charging current can also be read by the flick of a switch.
This will gove one a good idea how the panel is performing at any instant .
FollowupID: 322121

Follow Up By: Magnus - Friday, May 28, 2004 at 09:47

Friday, May 28, 2004 at 09:47

You been sneaking round spying on my rig!! I can tell!!

Yep, that's what I have. Salvaged an ammeter from a defunct battery charger. Ammeter reads from zero to 5 amps on a 2 inch square meter mounted on a jiffy box from Dick Smith along with a 2 position switch labelled Draw and Charge.

This lot is right next to the voltmeter from Jaycar mounted inside a clear faced jiffy box also from Jaycar. Keeps voltmeter protected as the whole lot (voltmeter and ammeter) is mounted on the front of the trailer where I can see it during day and night. My trailer has the trailer drawbar in the kitchen. Back to front to most others.

Takes a bit of nutting out to get the same meter to show draw and charge, but sit down with a big mug of coffee and draw it up on paper first. Not very hard when you spend a bit of time planning the wiring.

a reminder, don't waste your money on an auto style ammeter. Spend the extra $ on a good one from Jaycar. Will be less than $50 if I remember correctly from their catalogue. The Voltmeter will set you back $40. So for less than $100 you should be set. They also have an on line shop you can check out.

Have fun

FollowupID: 322146

Reply By: Member -Bob & Lex (Sydney) - Thursday, May 27, 2004 at 17:10

Thursday, May 27, 2004 at 17:10
Shawn, A 50 amp panel should do lights & music. As for charging on the move I used a second isolator from main battery to a 50 amp anderson plug cost $100 whereas a redarc to do 3 battries cost $600. If you are in Sydney I can give you a top auto elec to do it for you.
AnswerID: 60466

Follow Up By: Shawn - Thursday, May 27, 2004 at 17:20

Thursday, May 27, 2004 at 17:20
Bob, I'm in the Moorebank area.
I would be interested to know of the top auto elec you have found.
FollowupID: 322050

Follow Up By: Member -Bob & Lex (Sydney) - Thursday, May 27, 2004 at 17:46

Thursday, May 27, 2004 at 17:46
Shawn, check your member messages
FollowupID: 322056

Reply By: Shawn - Thursday, May 27, 2004 at 17:17

Thursday, May 27, 2004 at 17:17
Thanks to all who have donated info.
I have spent all afternoon (at work) looking at the suggested sites and have found answers to most of my questions, so thanks very much to all

AnswerID: 60469

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