Solar panel sizing for twin 105 amp batteries

Hi guys, my wife and I are off for a three month trip across the top of Aus (savannah way) and back to Sydney via the Tanami. We plan to do as much free camping as we can .
Our trip will begin in May 2011. What I need to know is what size of solar panel/s are needed to keep the two 105 Amp deep cycle batteries charged in our camper.
We run a water pump, 2 computer fans to help the 3 way fridge which we run on gas, 2 arlec 12v fluoro lights, radio/CD player and a laptop computer when needed we also use the 12v to recharge the mobile phones.

What size in amp should the solar charger/regulator be?
Thanks, Tim
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Reply By: Member - John and Val - Wednesday, Mar 31, 2010 at 11:08

Wednesday, Mar 31, 2010 at 11:08
Tim,

This article here will help you to work out your electricity generation requirements.

Cheers,

Val
J and V
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AnswerID: 411166

Reply By: Mandrake's Solar Power- Wednesday, Mar 31, 2010 at 11:36

Wednesday, Mar 31, 2010 at 11:36
By my reckoning you will need maybe 20aH per day as your biggest possible 12v output is on Gas !!
So based on 20 aH per day you need a 5 Amp reg and 100 watt panel should be OK - However once you plug that fridge in to 12v - this all changes dramatiically -
by 200% !! ( roughly ) .

There is a spreadsheet available for calculation of solar requirement on my website and if you were a member it is accessible in the members file area here ,

Cheers

Steve
AnswerID: 411171

Follow Up By: usguys07 - Wednesday, Mar 31, 2010 at 11:54

Wednesday, Mar 31, 2010 at 11:54
Hi Steve, if I go up to a 10, 15 or 20ah regulator/charger what would be the outcome? (is this size panel capable of handling this size reg, will it charge quicker if using a higher rated reg?
Thanks, Tim
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Follow Up By: Mandrake's Solar Power- Wednesday, Mar 31, 2010 at 12:14

Wednesday, Mar 31, 2010 at 12:14
Tim ,

If you get a larger reg it will still work with a small panel - it just means when / if you decide to get more panels you won't need to upgrade the reg to cover the extra Amps coming in .. But the bigger you go the more expensive the reg becomes ...

Cheers

Steve
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FollowupID: 681266

Reply By: Peter McG (Member, Melbourne) - Wednesday, Mar 31, 2010 at 11:50

Wednesday, Mar 31, 2010 at 11:50
Tim

You should be able to keep the batteries topped up by charging from the car alternator - if you are moving regularly. You may need a solar panel for when you're camped fopr longer stays.

Peter
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Follow Up By: usguys07 - Wednesday, Mar 31, 2010 at 11:57

Wednesday, Mar 31, 2010 at 11:57
Hi Peter, we will be stopping for a week here and there to get some fishing in.
We will leave the Ultimate in one spot and do some exploring from this base camp.
Tim
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Follow Up By: Peter McG (Member, Melbourne) - Wednesday, Mar 31, 2010 at 12:34

Wednesday, Mar 31, 2010 at 12:34
Tim,

I have 2 decent size AGMs in the Ultimate and charge tese from the car while travelling and then use a 60 watt solar panel to top up when camped. We have a 12v fridge and so need to use the generator after a few days but this works fine.

Much more on this topic on the Ultimate forum. Have you registered?

Cheers

Peter
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Reply By: Maîneÿ . . .- Wednesday, Mar 31, 2010 at 17:26

Wednesday, Mar 31, 2010 at 17:26
Tim,
I would go with the recommended 100 Watt panel, but lesser would be ok for short durations, the solar regulator has to be able to *regulate* the current (Amps) going into it from the panel, so if it's a 100 Watt panel you need a reg about 7 Amp MINIUM.
If you decide on a panel with a rated output, in Amps, of ~4.6 Amps (80 watt panel) then get a 5 Amp regulator – minimum, remembering that you may get extra solar panels in the future, it's less expensive to use a better quality, higher capacity regulator from the start.
The regulator being a higher capacity will NOT charge the battery any faster than a lower capacity regulator.

Look first at a decent regulator with an LCD screen, because you can see what is happening in the way of Amps available from solar system, Amps going into the battery, Voltage at the battery and history of charging, etc.
Then compare that to a lesser expensive non LCD screen reg.

Do NOT get a cheap 'on/off' regulator, get one just like any good quality 3 or 4 stage battery charger, that has at least trickle, float and boost characteristics.

Maîneÿ . . .
AnswerID: 411201

Follow Up By: usguys07 - Wednesday, Mar 31, 2010 at 18:20

Wednesday, Mar 31, 2010 at 18:20
Hi Maîneÿ, I was thinking along the lines of a 120watt follding panel for our trip.
What brands of regulators are available, to give you the functionality that you suggest? I'll look them up on the net.
Do all panels come with the regulator on the back of the panel or can you get a regulator and mount it where you want. I would like to mount it in the camper and run the cableing from there to the panels. Is this unusual to do it like that or is it ok.
Thanks, Tim
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Follow Up By: Maîneÿ . . .- Wednesday, Mar 31, 2010 at 20:59

Wednesday, Mar 31, 2010 at 20:59
Tim,
I use a LINK -> Steca solar regulator because it's one brand that will do everything I need of it and they are quality made products.

You must mount the solar regulator near the battery, NOT on the back of the solar panel, just as you have posted should be perfect.

Maîneÿ . . .
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FollowupID: 681319

Follow Up By: usguys07 - Wednesday, Mar 31, 2010 at 22:36

Wednesday, Mar 31, 2010 at 22:36
Thanks, Maîneÿ
Tim
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