Cheap solar panels .. worth it?

Plan to be self-sufficient with trailer batts charged off the car.

Should be good for 4 - 5 days while camped.

Wondering if by way of top-up/insurance a 15 W amorphous bought off ebay would be worth the $165.

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&rd=1&item=180322310529&ssPageName=STRK:MEWA:VRI

Advice appreciated.
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Reply By: Member - Troll 81 (QLD) - Wednesday, Jan 21, 2009 at 17:57

Wednesday, Jan 21, 2009 at 17:57
that won't charge it mate but we need more info on your setup there
AnswerID: 345397

Reply By: Sigmund - Wednesday, Jan 21, 2009 at 18:09

Wednesday, Jan 21, 2009 at 18:09
K, setup will be 2 x 96 amp hour batts.

Drain will be a small inverter, 2 x 12 V portable fluoros (c. 1 amp each) and a 37 l Waeco fridge (c. 0.8 amp).

I'm told this setup should be good for 4 - 5 days with batts fully charged.

Appreciate that a 15 W solar panel could never be the prime charge source, esp down south.

It's just top-up value for money that I'm looking at.

Apologies if the above makes no sense ... I'm an ignoramus when it comes to electricity.
AnswerID: 345401

Follow Up By: Maîneÿ (wa) - Friday, Jan 23, 2009 at 14:42

Friday, Jan 23, 2009 at 14:42
Sigmund,
so what do you use the Inverter for ??

Don't expect it to work more than recharge lights

Mainey . . .
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FollowupID: 613612

Follow Up By: Sigmund - Friday, Jan 23, 2009 at 15:42

Friday, Jan 23, 2009 at 15:42
Hmm ... it sposed to deliver 150 W cont and 250 W max. Not good enough for a laptop?
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FollowupID: 613619

Follow Up By: Maîneÿ (wa) - Friday, Jan 23, 2009 at 16:22

Friday, Jan 23, 2009 at 16:22
A misunderstanding of the *two* sentences.

Yes, the inverter will be suitable for a laptop, hope it's a PSW inverter ?

However, I should have been clearer with the second and said:
Don't expect it (the Solar panel) to work more than recharge lights

Mainey . . .
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FollowupID: 613625

Follow Up By: Sigmund - Friday, Jan 23, 2009 at 17:16

Friday, Jan 23, 2009 at 17:16
K ..

The inverter is a WAECO MCI-100-12 .. modified sine wave. I got the specs wrong. It's 100/200W
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FollowupID: 613632

Reply By: Boobook2 - Wednesday, Jan 21, 2009 at 18:16

Wednesday, Jan 21, 2009 at 18:16
Sigmund,

Here is what to do.

Take the $165 and put $15 aside. Then throw the remainder down the toilet. That way you will only waste $150 :-)

Seriously, unless you are only using a 11W flouro light for a couple of hours a day then 15 Watts of solar panel will do almost exactly nothing to help. And if that light is all you have then your batteries will probably last a few weeks anyway. A 15 W panel will deliver about 10W for 3 - 4 hours only I am afraid or enbough to run a standard fridge for a bit more than an hour. Barely enough to keep an unused battery charged.

If you have a few lights, and a fridge and want to be self sufficient for 3 days with say an 80AH battery then you will need a minimum of about 80Watt and probably more than 120W depending on your location, load etc.

As per above more info on your batteries and loads would help but I would be amaized if you can get away with less than 100Watts.

Don't buy it until you understand the issue a lot more. There are lots of people here that can give you ( a range of ) opinions.
AnswerID: 345402

Follow Up By: Boobook2 - Wednesday, Jan 21, 2009 at 18:18

Wednesday, Jan 21, 2009 at 18:18
Oops you posted while I was typing.

For that kind of load to make a dent in the current draw you would need 80W plus. A 15 w panel would add nothing. Another battery would probably be a better option if that is your budget.
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FollowupID: 613371

Reply By: Sigmund - Wednesday, Jan 21, 2009 at 18:25

Wednesday, Jan 21, 2009 at 18:25
Cool.

Fair 'nuff.

Waste of money then.
AnswerID: 345404

Follow Up By: pickle - Wednesday, Jan 21, 2009 at 19:10

Wednesday, Jan 21, 2009 at 19:10
Thats one damn efficient fridge that Waeco. Might have to get me one if it only draws 0.8 amp.
Dave
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FollowupID: 613377

Follow Up By: Sigmund - Wednesday, Jan 21, 2009 at 21:06

Wednesday, Jan 21, 2009 at 21:06
Yeah, FWIW that's what the retailer advised.

But as posted, I'm just looking at top-up, not to run a fridge, or fully charge the aux batts - and whether a cheapie solar panel would be worth the moolah.

So a 15 W panel would yield at best say 11 W. Then there'd be a discount for ambient temp and an adjustment for local solar avail. energy.

Guess I need to figure out the relationship btwn watts and amps, or is it amp hours ..?
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FollowupID: 613397

Follow Up By: oldtrack123 - Wednesday, Jan 21, 2009 at 22:42

Wednesday, Jan 21, 2009 at 22:42
Hi Sigmund
That Waeco alone will use between 30& 60 amphrs per 24hrs depending on how it is used.
watts diivided by 12 [ for12v]gives you amps .
Amps by anticipated use[run time]over 24hrs gives amphrs used in 24hrs.
A15w panel will barely hold a charge on a battery [ie hold it @ float voltage[stage] IT will not add any charge , FORGET IT.!!
As others have said 80w would be absolute mininum IF you have long bright sunny days.
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FollowupID: 613421

Follow Up By: oldtrack123 - Wednesday, Jan 21, 2009 at 22:52

Wednesday, Jan 21, 2009 at 22:52
Hi Sigmund
"Plan to be self-sufficient with trailer batts charged off the car."
Do you intend to set up a fixed camp & not move for that time ??
Were you considering just running the engine to charge the trailer batteries if so you need to run the engine for a looong time as the alternator output drops off rapidly & is not an efficient means of charging in that situation.

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FollowupID: 613422

Follow Up By: Member - Matt M (ACT) - Thursday, Jan 22, 2009 at 14:13

Thursday, Jan 22, 2009 at 14:13
Oldtrack,

The fridge will use nothing like 30-60 Amps per day. The 0.8 Amp figure is an average per hour and equates to a daily consumption of 19.2 Amps. Still a bit optimistic in real world conditions I admit.

I have a bigger (50l) Waeco and over a period of 6 months continuous use the very worst day (40 deg +) it used 37 Amps, not even close to 60. Best was 13. Average over that period was 26 Amps per day under a very wide range of conditions.

Matt.
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FollowupID: 613478

Follow Up By: oldtrack123 - Thursday, Jan 22, 2009 at 16:00

Thursday, Jan 22, 2009 at 16:00
Hi Matt
I don't disagree with your figures they are no doubt correct for your conditions of use. But actual amphrs per day depends heavily
on many factors,
Ambient temp [ noted yours of40deg]
Thermostat setting, IF set to freeze will run a very long time.
I normally consider about 2deg to be a safe temp to allow for variations, long storage of meat, etc & prevent food poisoning.
Amount of warm goods put into fridge, uses quite a bit of power to cool down.
.Lid/door opening frequency & for how long.
I believe 30 amphrs is near to what most users would use & not far from your 26 amphrs per day average. but if in high temps heavily loading with hot goods &/or running @ freeze for long term preservation ,60amphrs could easily be used in any one day.
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FollowupID: 613488

Reply By: Motherhen - Wednesday, Jan 21, 2009 at 19:40

Wednesday, Jan 21, 2009 at 19:40
An 80 w panel and one 100 a/h battery keeps us in power with Engel car fridge and a couple of fluro lights. We tried to run a second Engel as a freezer but had wet or cloudy weather and was struggling.

We have replaced the caravan batteries, and will try using two from the caravan (still good) in the F250 and see how the panel handles them.

Motherhen

Motherhen

Red desert dreaming

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AnswerID: 345406

Follow Up By: Sigmund - Wednesday, Jan 21, 2009 at 21:08

Wednesday, Jan 21, 2009 at 21:08
Thanks Motherhen.

V. helpful.
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FollowupID: 613400

Follow Up By: Pete Jackman (SA) - Thursday, Jan 22, 2009 at 01:13

Thursday, Jan 22, 2009 at 01:13
We run a Waeco CF50, 2 fluro lights, camera and phone chargers and a laptop from 90W of panels and 2 x 35AH batteries. This is good for static camping in sunny weather. A few days of cloud means the genny gets a run for a few hours.

Pete
Any mug can be uncomfortable out bush

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Reply By: Member - John and Val W (ACT) - Wednesday, Jan 21, 2009 at 22:02

Wednesday, Jan 21, 2009 at 22:02
Sigmund,

You might care to check out our blog on electricity for camping. It discusses the various loads and sources of electricity. FWIW our daily load is about 36 amphours, your 15W panel might supply up to 6 amphours!

Cheers,

John
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: 345443

Reply By: Sigmund - Thursday, Jan 22, 2009 at 06:45

Thursday, Jan 22, 2009 at 06:45
Thanks all for taking the time to educate a newbie.
AnswerID: 345463

Reply By: Ron173 - Thursday, Jan 22, 2009 at 12:11

Thursday, Jan 22, 2009 at 12:11
G'Day,
as youve gathered by now, 15w is not going to touch the sides.

Your lights are minimal but once you bring a fridge into it it gets more serious.

Buy best you can afford both in panel and battery,

I have a 120a/hr battery with a 60w panel, which runs my 40ltr engel fine even in cloud it keeps up and has never gone flat on me.

I also have an 18ltr waeco, and can run it as a small freezer too, panel copes just, but needs full sun all day or I need to top up with my genny and 25a charger for couple hours.

I dont often do this as its pushing things a bit, but just to give you an idea.

Rgds

Ron
AnswerID: 345490

Reply By: Sigmund - Thursday, Jan 22, 2009 at 14:59

Thursday, Jan 22, 2009 at 14:59
Thanks.

Yeah, will be lobbing in to a site with 2 x 96 amp hour batts fully charged. I understand now that a 15 W rated panel is pretty useless.

Had just been wondering about the cost effectiveness of one for a bit of top-up.

That said, in the future I will want to be fully independent of the alternator, so it will either be decent panels or a gennie. (And I hate the noise of gennie's in the bush!).
AnswerID: 345512

Follow Up By: Maîneÿ (wa) - Friday, Jan 23, 2009 at 14:52

Friday, Jan 23, 2009 at 14:52
every guy with-out one will tell you they hate the noise
the guys with them have to put up with the noise, so they say it's quiet and no-one should winge, quiet is when you can enjoy the sounds of the bush around you

the price of a 'decent' genni and a decent solar panel would be similar ?

Mainey . . .
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FollowupID: 613615

Follow Up By: Sigmund - Friday, Jan 23, 2009 at 15:52

Friday, Jan 23, 2009 at 15:52
Yep.

And yep.
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