How many solar panels

Submitted: Sunday, Dec 14, 2008 at 18:55
ThreadID: 125256 Views:3405 Replies:8 FollowUps:1
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I would like some comments on 3 versus 4 solar panels. We are looking to buy a second hand bushtracker and are weighing up what extras we really need as we would like to keep the weight down as much as possible. We have a portable solar panel and thought we might be able to use this to run the Engel in the car. We also plan on taking a generator as a backup. We will be camping out as much as we can.
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Reply By: Searenity - Sunday, Dec 14, 2008 at 19:24

Sunday, Dec 14, 2008 at 19:24
my wife and I are in the middle of the order process with BT. The number of solar panels and batteries has been extensively discussed. The general consensus is one X 125 watt panel per battery followed by an estimation of the battery power required for your uses. Other considerations are whether your BT is primarily 12V DC or 240V AC van. If you are primarily AC then you will have an inverter which does require more baseload power.

Also the time which you use electricity must be taken into consideration - if you watch TV, play music, read etc. for extended periods during the evening then your battery requirements will be high and the solar cells will not recharge till the next sunny day. Microwave cookers demand considerable power. This suggests a bigger baseload requirement and hence more / better batteries. There is a real need to do your energy consumption sums i.e. power out versus power in and at what times - as a crude method of determining battery capacity requirements.

One other consideration is maintaining the peak condition of the batteries. As a general rule batteries last longer if they are charged to maintain their peak capacity.

In our case, we are primarily a 12V van - no inverter and no microwave - we have settled for 3 X 125 watt panels and 3 batteries. This is also an attempt to keep the weight down

If you are a 240V van with a large inverter and possibly a microwave then logic suggests greater capacity requirements - maybe 4 X 125 watt panels and 4 batteries but note the associated increased weight.


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Reply By: Motherhen & Rooster - Monday, Dec 15, 2008 at 05:05

Monday, Dec 15, 2008 at 05:05
Hi Wendys and welcome

Our 18' BT came pre-loved with 4 x 120 w panels. We are low power users and had enough power until we got to the Kimberley this winter. We had no idea how much power we should have had. Two of the panels had been added on by a subsequent owner and were from the faulty batch. Kyocera replaced all four with their new 130 w panels (same size). We have now upgraded from three to four batteries to store it. We had a portable 80 w panel, which we mounted on the roof of the F250 to run the Engel, as well a our lights when camping away from the caravan (with one battery). We got our generator principally to run the air con or emergency power tools, but needed it in the Kimberley until the panel situation was resolved. It depends on how much you want to run on power - we running on about 1½ usable panels until this year! The panels are not heavy, but the batteries are. I hope this helps you decide.


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Reply By: Grumblebum & Dragon - Monday, Dec 15, 2008 at 06:18

Monday, Dec 15, 2008 at 06:18
Hi Wendy,

It also depends on where you travel to.......... we tend to follow the sun and hate the cold. We have travelled for 3.5 years with three panel and three batts - but the van is pre-wired for a fouth panel and battery. I doubt we will ever upgrade.

It takes several days of dull rainy weather to cause us to get the Honda genny out and then it does not take long to bang the batteries up again. We have a 1200 watt inverter.

You also need to check your weight limits.

Regards John
AnswerID: 576531

Reply By: Len & Judith - Wednesday, Dec 17, 2008 at 03:11

Wednesday, Dec 17, 2008 at 03:11
i changed the lights to leds (via ebay _hongkong supplier) we have to boost the 3 batterys by geny. if we get several wet days,o therwise 3 panels 3 batts work well len
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Follow Up By: Grumblebum & Dragon - Wednesday, Dec 17, 2008 at 07:11

Wednesday, Dec 17, 2008 at 07:11
We are ditto re LED's - changed al the MR16 downlight spots to LEDS

I initially went the eBay route for these ex Hongkong as they were cheap, but they did not last well started popping individual LEDs. Since got some from Steve G, these have a 12v regulator/stabiliser or some such. Since then no more problems

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Reply By: Mobi Condo - Wednesday, Dec 17, 2008 at 03:30

Wednesday, Dec 17, 2008 at 03:30
We have a standard 3 panel - 3 battery setup and since new (Nov 2005) have had no need of a Generator.

Even when stuck in rain for a week at Mt Elizabeth in July 2007, we had power for 240V AC (off the 1800W Inverter), lights and water pumps.

As we are used to basic camping we easily live without use of TV, sound system, DVD's etc (we have them on board though).

Even with rain falling from heavy cloud cover we still achieved 0.5 - 1.0 or so amps input!

For what this is worth!

Cheers - Ian & Sally
AnswerID: 576533

Reply By: NIK `N` OFF - Wednesday, Dec 17, 2008 at 04:27

Wednesday, Dec 17, 2008 at 04:27
We have 4 and 4, when we are independently camping for many weeks at a time around Ningaloo and usually running an engel freezer in the van as well as another engel fridge in the truck plus all the other do-dads i have sometimes wished for 5 panels, the sun sits lower in the sky and you need as many panels as you can to catch the energy whilst it's available, or panels that can be tilted to follow the sun better. If your moving every few days 3 + 3 could well be enough. A panel weighs around 11kg and battery 30kg.

Mick & Vickie

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AnswerID: 576534

Reply By: Fred & Marj - Saturday, Dec 20, 2008 at 00:13

Saturday, Dec 20, 2008 at 00:13

We have just come back to tassie after 4months on the road - including the last muster at Quilpie we have 4 x 130W panels and 4x Geltech batteries and didn't need to fire the generator up once - the biggest drain on the system is the fridge which is of cause higher in hot weather but then you usually have sun and at a lesser angle so the solar panels nhave no trouble keeping the batteries charged.

We did have several days of rain but were in a caravan park then and used the 240v which we were forced to use since most parks we have come across don't cater for unpowered sites.


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Reply By: 11-UPS - Sunday, Dec 21, 2008 at 01:46

Sunday, Dec 21, 2008 at 01:46

Jacki & I have lived in our van for the last two years and have found that 4 panels is a minium if you have a few electrical luxuries. We have a 1800w inverter which is used to recharge and run the laptop,microwave,toaster,3rd battery& fridge in car plus Jacki's breadmaker (500w Sunbeam). Started out with 3 but found not suffient in overcast conditions for any period past 3-4 days and didn't recover batteries properly being use on fulltime basis.Also have generator as backup.

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