Solar set-up quickie

Submitted: Monday, Jan 21, 2008 at 01:32
ThreadID: 53732 Views:3755 Replies:11 FollowUps:12
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Gday, have done an archive search and I'm pretty sure the solar set up I'm thinking of will do the job. Any other advice appreciated please before I fork out my hard-earned.

Will a BP 100w (2 X 50w) solar panel be sufficient to power my 40 litre Engel, fluoro light, occasioanl dvd etc, running through an 80 amp/hour lifeline AGM? I'm really after a system that will power itself independently for long-term stays.

I've tried calculating watt/hours etc but interested in other people experiences too.


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Reply By: Member - Uncle (NSW) - Monday, Jan 21, 2008 at 07:20

Monday, Jan 21, 2008 at 07:20
Hi there Barnesy, we have had our camper up for the last 2 weeks in Jodie's mum's back paddock at the farm. Getting ready for our trip next month, I wanted to make sure all was well and up to scratch so we have had the TV running for 3 to 4 hrs a night along with ARB fluro lights.
I bought one of Derek's twin panel set ups a while back and I can say it works very well for our needs. I have 3 Aux batts all up so I just rotate the panels between them when they need it. We wont be watching much TV when we are away but I used the TV as another drain source on the batteries besides the 60 litre Evakool fridge. I prefer these panels, to fixed ones as Jodie can keep them "following the sun" while I'm out detecting. Hope this helps out a bit cheers Unc.!MPG:110!
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Reply By: Member - Brian (Gold Coast) - Monday, Jan 21, 2008 at 09:10

Monday, Jan 21, 2008 at 09:10
Not sure about the BP one.... but I have a GP-100 watt bi-fold and have not had any drama's keeping the battery charged enough to keep our 70 litre Trailblaza happy. I would think the duty would be similar if not the same.


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Reply By: Steve - Monday, Jan 21, 2008 at 09:34

Monday, Jan 21, 2008 at 09:34
Hi Barnesy,

Difficult to be exact - but I reckon you'd be the right side of borderline. More solar, say 2 x 65w or similar would be better. Depends how much you will be driving, therefore charging from alternator etc. but certainly, given good conditions, you'd be ok.
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Reply By: Rod - Monday, Jan 21, 2008 at 10:24

Monday, Jan 21, 2008 at 10:24
I have 80W of solar and a Evakool fridge/freezer and that is not enough for tropical NQ.

100W might be OK for cooler climates and sunny days.

120W seems to be conventional wisdom to allow for northern temps and rainy days.
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Reply By: normo - Monday, Jan 21, 2008 at 12:43

Monday, Jan 21, 2008 at 12:43
take a look at this link, It might give you a bit more confidence in your decision.
Solar Basics

Also from the bureau of meteorology web site you can access maps of Australia showing the average peak sun light hours per day for each month of the year.

AnswerID: 282881

Follow Up By: jdwynn (Adelaide) - Monday, Jan 21, 2008 at 14:56

Monday, Jan 21, 2008 at 14:56
Excellent link Normo.

Do you / anyone know what is the draw of a 40l Engel per day. Link site calculates 384 wh/day. On that basis Barnesy might be underdone with his battery and panels.

Cheers JD
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Follow Up By: normo - Monday, Jan 21, 2008 at 16:19

Monday, Jan 21, 2008 at 16:19
The draw from a 40l Engel (the newer model) is approx 30 watts per hour when it is running continuously.

So if your fridge is in a cool location and also in a transit bag and set to a reasonable temp on average it will only cycle for about 20mins per hour (for the purposes of calculating power requirements it's advisable to over estimate rather than under estimate). So over a full 24 hour period it would roughly be 240watts which equated to approx 20AH.
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Follow Up By: Mainey (wa) - Monday, Jan 21, 2008 at 19:45

Monday, Jan 21, 2008 at 19:45
normo, I don't have a calculator but 20ah looks really savage for any fridge.
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Follow Up By: Member - Barnesy (SA) - Monday, Jan 21, 2008 at 20:08

Monday, Jan 21, 2008 at 20:08
Thanks Normo. I will have a good look at this site after i finish work.
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Reply By: Member - Lance S (VIC) - Monday, Jan 21, 2008 at 16:03

Monday, Jan 21, 2008 at 16:03
G'day Barnesy, i run a 110lt waeco and 3 fluro's on 2 x 80w BP (BP380J)solar panels running parallel with a PV charge controller made by powertech. Some say it is an overkill, but i thought paying the little bit extra to have piece of mind was worth it. Bought mine thru Jaycar.


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AnswerID: 282904

Reply By: Axel [ the real one ] - Monday, Jan 21, 2008 at 16:56

Monday, Jan 21, 2008 at 16:56
How long is a "day" ?? To give a definative answer to your question is almost impossible due to the many variances in fridge use and actual sunlight but can give you an example of usage , we run a 80lt Waeco as fridge and freezer [freezer at -18c ] and a 15lt Engle at 3c ,,,, 1x 125w Kycera + 1x 64w Unisolar panels that in "perfect" conditions will produce 12amp per hr ,, a little thing called peak sun hrs comes into play ,, peak hrs x 12 = an average [ for our set up and area ] of only 72 amps per day ,[ remember this is variable + and - ] , now I know that our Waeco uses on average 64amp hrs per 24 hrs and the Engle uses 42 amp hrs per 24hrs ,,,, 64 + 42 = 106 per 24 hrs ,, end with a deficit of 34amp per 24hrs ,
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Follow Up By: normo - Monday, Jan 21, 2008 at 17:14

Monday, Jan 21, 2008 at 17:14
By your calculations your Engel fridge must be running for an average of 42mins per hour.
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Reply By: Sand Man (SA) - Monday, Jan 21, 2008 at 19:11

Monday, Jan 21, 2008 at 19:11

I reckon the 100 watt solar panel will perform admirably, unless you have some very dark days indeed.

It is fairly hard to calculate watts used, etc. as the variables are too great. Experience is the best guide.

I use 1 x 40 watt BP panel on a 75Ah Thumper and have run my 40 litre Engel "continuously" for three days and the battery system still showed "charged". I also run a couple of lights for a few hours of an evening when camping.

In full sunlight the 40 watt panel is outputting around 2.5 amps, continously for several hours per day.

I have the option of adding a second panel (80 watts all up) if I need it, but I just haven't found the need.

The Engel cycles on and off so it is not drawing the full amount of amps (about 2.7 max) all the time.

Maybe my experience will "bite me on the bum" come the National Gathering in July, but I also have the backup of the auxiliary battery in the Jack and the ability to charge all batteries while travelling, so I'm pretty comfortable.

If I find insufficient sunlight is affecting the charging capacity to any great degree, then I may purchase another panel.

My thoughts are, you would be very unlikely to require more than a 100 watt panel to feel comfortable.


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AnswerID: 282939

Follow Up By: Member - Barnesy (SA) - Monday, Jan 21, 2008 at 20:02

Monday, Jan 21, 2008 at 20:02
There are a lot of variables in calculating watts/hour etc. That is why I'm asking for people's experiences.

It is looking like the 100w panels will just about do the job given I am wary of varying conditions. But I can't be too extravagant with my power usage.

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Reply By: Mainey (wa) - Monday, Jan 21, 2008 at 19:39

Monday, Jan 21, 2008 at 19:39
you say you want advice 'before' you spend the hard-earned lol

Three questions:
(a) Why will you buy 2 small panels ?
(b) What brand of Solar regulator will you use ?
(c) What has induced you to buy a 80ah "lifeline" battery ?

AnswerID: 282950

Follow Up By: Member - Barnesy (SA) - Monday, Jan 21, 2008 at 19:58

Monday, Jan 21, 2008 at 19:58
1) i will buy 2 small panels because they are easier to store in the 4wd than 1 big panel.
2) i am trusting the regulator that Derek from ABR uses.
3) lifeline battery because they are top of the range. 80 a/h because the dimensions are right to fit in the storage area of my 4wd. 100 a/h too large.

Does that answer your questions Mainey? lol
FollowupID: 547502

Follow Up By: Mainey (wa) - Monday, Jan 21, 2008 at 20:15

Monday, Jan 21, 2008 at 20:15
1) different people have different opinions, I respect yours.
2) Steca (made in Germany)
3) it's only 290mm wide, a small battery ?
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Follow Up By: Member - Barnesy (SA) - Monday, Jan 21, 2008 at 20:23

Monday, Jan 21, 2008 at 20:23
2) Steca, i'm trusting it's good, most things from Derek are.
3) the area i have to keep batteries in my storage in the back of the 4wd is rectangular. I can either fit 1X 100 a/h in it or 2X 80 a/h. At some later stage i may want to get another 80 a/h then it can fit.

I will have a read of your rig page as it seems like you have gone into some detail with your solar set up.

FollowupID: 547514

Follow Up By: Mainey (wa) - Monday, Jan 21, 2008 at 20:31

Monday, Jan 21, 2008 at 20:31
In my opinion Steca is best performance available, but I'm biased lol
You need Amps to be just above the TOTAL Amps of the Solar SYSTEM, so if you intend up-grading the solar system later get a larger capacity reg now.

Definitely advise you to get two batteries NOW, wire them in parallel.
Fitting an old battery and a new battery is not the recommended way of charging AGM's by Solar.
FollowupID: 547518

Reply By: Mogul - Monday, Jan 21, 2008 at 20:17

Monday, Jan 21, 2008 at 20:17
I spent 3 months researching our set up before buying.

What I found was that everyone will tell you something different about how their setup works and why it is better than everyone else's.

All I can suggest is the following:
1. Don't skimp on your calculations, use the worst case scenario and then add 10% extra.
2. Take into account that there may be 3 or 4 days with basically no input due to inclement weather.
3. Consider mounting to roof of car rather than carrying around in the back where they could easily be damaged.
4. Buy tried and proven gear.
5. By buying a bigger panel than you need there will be less "sun chasing" throughout the day.

I have a 123W Sharp panel, connected to a 120AH battery through a 20A powertech regulator.

The best I have achieved from the panel moving it 3 or 4 times a day has been 58AH (8.00am to 6.30pm, no clouds), average 35AH to 45AH. During days of no sun lucky to get 10AH on some days.
AnswerID: 282957

Follow Up By: Mainey (wa) - Monday, Jan 21, 2008 at 20:40

Monday, Jan 21, 2008 at 20:40
2. With a larger battery capacity, (example only) 200ah instead of 100ah, you can get away with the few days of NO SUN, but [some]solar panels don't require 'direct' sunshine to work, they will work in inclement weather with clouds.
3. Best idea (IMO)
4. For sure
5. makes for a Holiday with-out shifting panels etc.
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Reply By: Ron173 - Tuesday, Jan 22, 2008 at 12:09

Tuesday, Jan 22, 2008 at 12:09

I'm with sandman above here.

People will tell you this that etc, and its true buy the biggest you can afford, however..

Reality is more than paper calculations, and what works and what doesnt.

Some panels despite wattage, function more consistently than others, and some need full sun whilst others dont.

I use a 60w Kyocera, on a 120AH battery, running a 40ltr Engel as a fridge around 1 deg, never had it run out on me yet, I have also done 3 consequetive cloudy days and it was still maintaining 30%, I got full sun on 4th day which totally recharged it.

I do move it about 3 times a day to follow sun, and on most days its showing fully charged by 11am.

As said, so many variables, its almost impossible to work out accurately on paper, you might get a rough idea but field trials beat paper calculations.

Also I find ambient temp whilst a factor, doesnt affect me much, as if its 40 deg, yes fridge running more, but generally if its 40deg, panel is in full sun and is putting out max too.

Just my experience like you asked.

AnswerID: 283093

Follow Up By: Member - Barnesy (SA) - Tuesday, Jan 22, 2008 at 18:21

Tuesday, Jan 22, 2008 at 18:21
Thanks Ron.
FollowupID: 547748

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