solar panel sizes

hi all, just wondering if anyone could offer info on solar panels.I guess i'm looking at what size to buy and where to get it from?
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Reply By: Member - Mike DID - Thursday, May 07, 2009 at 14:41

Thursday, May 07, 2009 at 14:41
It depends totally on what you want to run from the panels.
AnswerID: 363691

Follow Up By: Member - Daniel M (QLD) - Thursday, May 07, 2009 at 15:17

Thursday, May 07, 2009 at 15:17

For the most part they will only be running the fridge. It will only be for when we are parked up for any length of time as the car will charge as we go. i guess there probably would be the odd light/battery charger running off them from time to time but not to any extreme.
FollowupID: 631374

Reply By: jdwynn (Adelaide) - Thursday, May 07, 2009 at 14:43

Thursday, May 07, 2009 at 14:43
hi Daniel

Having just ben through all that, trying this:
AnswerID: 363692

Follow Up By: jdwynn (Adelaide) - Thursday, May 07, 2009 at 14:49

Thursday, May 07, 2009 at 14:49
Now with link LOL!
Site Link

This spreadsheet looks complex but its straighforward if you give yourself a bit of time to understand it. It's all there. If your not familiar with spreadsheets get someone to give you a hand.

Let us know how you get on.

FollowupID: 631368

Follow Up By: Member - Daniel M (QLD) - Thursday, May 07, 2009 at 15:24

Thursday, May 07, 2009 at 15:24

Thanks for that. Unfortunately i seem to be having some trouble opening the spreadsheet. It's a bit of a tragedy as i've had to ask for help off the the lovely lady of the house.will keep trying however as it looks like a good read.

FollowupID: 631375

Reply By: Member - John and Val W (ACT) - Thursday, May 07, 2009 at 15:31

Thursday, May 07, 2009 at 15:31

Check out our blog Electricity for Camping. This discusses power requirements and how to meet them.

There is also a very good article here on ExplorOz.


J and V
"Not everything that can be counted counts, and not everything that counts can be counted."
- Albert Einstein

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AnswerID: 363700

Reply By: Member - Josh (VIC) - Thursday, May 07, 2009 at 18:45

Thursday, May 07, 2009 at 18:45
It's not just the solar panel but the whole set up you need to look at. We have 2 6volt batteries joined which run our 80 lt evacool (40 fridge 40 freezer) and lights when bush camping. The 2 6volts charge quicker than 1 12volt. We have an 80 watt bp solar panel and it handles it with ease. We also have an evacool inverter for when we have power. The Battery size and amp hour affect the effectiveness of the panel Charging. We changed batteries awhile back and they took forecer to charge. went back to what we know and it works fine.

AnswerID: 363723

Follow Up By: travelguy62 - Friday, May 08, 2009 at 17:42

Friday, May 08, 2009 at 17:42
Hi Josh
Can you tell me what amphour rating you 6 volt batteries are.I have 2x 225ah 6volt batts and 2x 75watt panels going to a 30amp 3 stage controller.I am concerned my batteries maybe a little large for this system as I have not fitted it into the camper at this stage.
Thanks Guy
FollowupID: 631549

Follow Up By: Member - Josh (VIC) - Friday, May 08, 2009 at 19:32

Friday, May 08, 2009 at 19:32
Hi guy,
We have 2 supreme 235 ah batteries with a projector 12 volt auto computer protector controller. This runs our fridge/freezer and fluro lights. The batteries last about 4 days before needing charging even with the fridge set half to freezer. The panel will bring back from a fairly low charge with good sun very quickly. On cloudy days it holds it own but does not put a whole lot back in. Will generally hold at whatever percentage of charge it is plugged in at. Goes up a little and down over night. Started with Trojan which were fantastic, until they died after nearly 2 yrs of continuous hard use. Put century batteries in which were crap and faulty from the start. The guys who built our trailer now use these supreme batteries. They recon they are the bees nees.

FollowupID: 631572

Follow Up By: travelguy62 - Friday, May 08, 2009 at 20:17

Friday, May 08, 2009 at 20:17
Hi Josh,
I am using trojans for this set up.I would think you would get more out of your batteries.Do you know how many amps the fridge is using and do you keep the panel connected all the time while camping.Also do you use any other form of charging.Sorry for all the questions and hope you dont mind me asking. Thanks Guy
FollowupID: 631579

Follow Up By: Member - Josh (VIC) - Saturday, May 09, 2009 at 11:03

Saturday, May 09, 2009 at 11:03
Hi guy,
Don't mind the questions all, that's how we learn and that's what I love about this forum. I thought we might have got more out of the batteries to but after talking to a few battery guys none were surprised with what we have done with them. 18 months full time use varying temps from -4 to 50 degrees.
Our fridge uses about 1.5-2 amps/hr according to the evacool website at 32 deg ambient temp. Run as half fridge half freezer. It will freeze fresh meat etc. Have not checked it my self. The fluros draw about 1amp/hr.
If we are staying for more than 2 days we connect the solar panel other wise don't bother. The trailer batteries charge off the car via an anderson plug while driving. We find this setup works very well.
Make sure any wire you use for charging from solar panel or car is heavy duty. A few auto elecs have said ours is heavier than it needs to be but I have met others with similar set ups that have current lose and don't charge as quickly with thinner wire. For the extra couple of bucks to go next size up can save hassle of not being able to keep charged. We spent 3 months in Tassie first up camping with no power the whole time and had no problem with charging at all. If we get heaps of rain and batts getting low we connect the car and run for half hour to get them up a bit.
Hope this helps. If I can work out how to do it I will post a photo of the set up.

FollowupID: 631651

Follow Up By: travelguy62 - Saturday, May 09, 2009 at 12:44

Saturday, May 09, 2009 at 12:44
Hi Josh,
Batteries and solar tend to be a bit of an unknown quantity and a bit of trial and error.Thanks for your information and it all helps with learning and understanding it all.
Thanks Guy
FollowupID: 631665

Reply By: Maîneÿ . . .- Friday, May 08, 2009 at 09:36

Friday, May 08, 2009 at 09:36
I choose to use a 2OO+ Watts Solar system to charge 2OO+ ah of AGM batteries.
The AGM battery system, being a reasonably large capacity, never gets below 12 Volts, even when running a Fridge/Freezer that draws (a massive) 10 Amps.

Yes, you will be able to get away with a much smaller capacity Solar system, how small you require will depend on what battery power you use in a 24 hour period.
The Solar system will be effectively working at something like "peak performance" for only ~6 hours, so realistically you need to be able to replace four times the battery consumption rate.

Said simplistically......
if your fridge draws 6 Amps and runs on a duty cycle of 45%, then by the maths, you must replace:
2.7 ah x 24 hours = 64 ah daily, in just ~7 hours
which equates to: ~9 Amps or ~15O Watts of Solar power.
Add a few lights and other 'important' accessories and you will see how things can get quickly out of hand and battery performance will suffer.

The various (Solar) pictures shown in my 'profile' (below) clearly indicate how my Solar system is capable of maintaining the AGM battery system at peak operating performance.

Mainey . . .
AnswerID: 363817

Follow Up By: Member - Daniel M (QLD) - Friday, May 08, 2009 at 12:17

Friday, May 08, 2009 at 12:17

Wow, that's impressive. Particularly like the hi clone quip in your profile. Good to see there are a few people out there giving them a fair go. My father has two in his jeep and he is also satisfied with them. Thanks to all for the info its been a great push in the right direction.

FollowupID: 631497

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