Who needs an alternator? Solar panels on the bonnet?

Submitted: Wednesday, Nov 06, 2013 at 20:09
ThreadID: 105024 Views:8152 Replies:14 FollowUps:33
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Solar panels are sooooo cheap these days and now there's a whole range of flexible thin panels as well.

So today, I was chatting to a mate with a DMax and Caravan. Second battery/isolator would be complicated and expensive in the DMax. His caravan came with solar panels and twin AGMs and works fine independently i.e. his solar panels provide plenty of power to top up the batteries for the compressor fridge and LED lights.
For his DMax he's skipping the idea of a Redarc DC-DC - he doesn't need it - solar panels on the Dmax roof or canopy should have that covered - single AGM in the canopy charged from solar and running an Engel.

It got me thinking - my TVan doesn't need the Anderson Plug - I find the 65W solar panel charges the AGM just fine. So what about the 200series - I just run a 40L Engel and LED lights - and there's lots of new flexible solar panels on the market now - only 2.5mm thick.

My thoughts are that I should use the bonnet for the solar panels - Velcro is great for attaching anything - so my first guess is that I should Velcro an 80 watt flexible panel to the bonnet, and use that as the sole method of recharging the second battery under the bonnet.

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Reply By: Member - Toyocrusa (NSW) - Wednesday, Nov 06, 2013 at 20:20

Wednesday, Nov 06, 2013 at 20:20
Hi Phil. I thought once a Solar panel got above an optimum temperature it started to reduce voltage output. If you mount these flexible panels onto the bonnet what would happen with engine heat rising into them as well as not having an air flow under them. Just my thoughts, I don't know exactly. Bob
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Follow Up By: Member - Phil G (SA) - Wednesday, Nov 06, 2013 at 20:25

Wednesday, Nov 06, 2013 at 20:25
Yes you're right. Not sure how hot it really gets on a 200series bonnet and how much is due to sun? The bonnet is double skin - so cool air goes between the two skins then into the intercooler and there's a wad of soundproofing - so I'm guessing it may not be a lot warmer than the roof. I'm a bit reluctant to use the roof because we carry a big kayak sometimes.
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Reply By: Ron N - Wednesday, Nov 06, 2013 at 20:25

Wednesday, Nov 06, 2013 at 20:25
Phil, I'd envision more than a little embarrassment for you, if a velcro-attached solar panel came unstuck from your bonnet at speed, and wrapped around your windscreen!
I could well imagine Mr Plod would also take a dim view of this form of attachment for a solar panel on your bonnet!

The bonnet mounting of solar panels is attractive, but I would expect that the "authorities" would like to see a more secure method of attachment.
I'd suggest one of the Sika range of Sikaflex panel adhesives could be more the order of the day.

I'm not sure of the total weight or number of panels that you propose - but keep in mind, a bonnet panel is not designed to be weight-bearing, and flexing of the bonnet panel on rough roads could possibly cause cracking of the panel, or the hinges, or the hinge mounting points.
Accordingly, I'd expect an aluminium stiffener at least, would be needed to support the panels and to reduce bonnet flexing.

Cheers, Ron.
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Follow Up By: Member - Phil G (SA) - Wednesday, Nov 06, 2013 at 20:31

Wednesday, Nov 06, 2013 at 20:31
A flexible 80 watt panel weights 2.5kg so weight is not an issue. Ideally a bit of airflow under the panels ( aided by a few mm of velcro) is desirable. I've used Velcro a lot - it has held most of my rigs together for many years. It would be nice to be able to remove the panels around town and when you sell the car - leave no trace.
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Follow Up By: Member - Phil G (SA) - Wednesday, Nov 06, 2013 at 20:36

Wednesday, Nov 06, 2013 at 20:36
Ron, here's a link for a potential panel:
80W flexible solar panel
Just trying to think outside the square this time round!
It might need the backup of a simple Redarc isolator as well in case weather gets too dull...
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Follow Up By: Ron N - Wednesday, Nov 06, 2013 at 21:28

Wednesday, Nov 06, 2013 at 21:28
Phil, I'm thinking like a scumbag thief right about now - and imaging how much I could make in a week, ripping velcro-attached $229 solar panels off the bonnets of 200 series 'Cruisers, as soon as the owners left them unattended, for more than 5 mins. [:-)

Me? - I like to screw stuff down that looks mightily attractive. Perhaps it's because I've lost so much to Hydraulic Jacks over the decades. [:-(
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Follow Up By: Member - Phil G (SA) - Wednesday, Nov 06, 2013 at 21:51

Wednesday, Nov 06, 2013 at 21:51
Yep, good point Ron!! Fortunately not too many thieves hang out in the deserts. I'd have to take them off in "civilisation".
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Follow Up By: Ron N - Wednesday, Nov 06, 2013 at 22:03

Wednesday, Nov 06, 2013 at 22:03
You haven't been to Kalumburu? BIL (copper) travelled to aforesaid destination and took his wife along. She went for a ride on a quad bike with one of the "locals" and made the mistake of carrying, and then accidentally dropping her purse, off the quad bike.
It disappeared within minutes - and despite looking for it, and asking all the "locals" if it had been seen, she never saw it again!
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Reply By: Robin Miller - Wednesday, Nov 06, 2013 at 20:42

Wednesday, Nov 06, 2013 at 20:42
Hi Phil

I guess I have been running almost invisible flexible panels on my Patrols roof for some years now and I have found some issues.

First is that there are different types , ones with large aluminium back plate are to be avoided as the expansion due to heat is to great.

The latest types can use a sort of printed circuit board on a smaller plate and I am currently using 20w ones.
This reduces metal expansion stress and makes them more independant from partial shading.

I now mount them with a few pieces of double sided tape around the edges and a couple in the middle - this has the effect of lifting the panel clear of the roof by about 2mm.
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Reply By: olcoolone - Wednesday, Nov 06, 2013 at 20:52

Wednesday, Nov 06, 2013 at 20:52
Great untill it becomes overcast and raining or you have tree coverage or your parked in a way you only get sunlight for a few hours a day.
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Follow Up By: Member - Phil G (SA) - Wednesday, Nov 06, 2013 at 20:58

Wednesday, Nov 06, 2013 at 20:58
Yeah, a simple $100 Redarc might be good backup.
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Follow Up By: Road Warrior - Thursday, Nov 07, 2013 at 12:23

Thursday, Nov 07, 2013 at 12:23
Just on that Redarc subject, I've just had fitted to my car the Redarc smart solenoid/isolator that allows "backflow" to the cranking battery from a charging source in the van, if it detects the cranking battery is a bit low.

Could be relevant to your idea, saves you plastering solar panels all over your bonnet lol
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Follow Up By: Member - PJR (NSW) - Friday, Nov 08, 2013 at 13:04

Friday, Nov 08, 2013 at 13:04
Same here. And I can also parallel the batteries for winching. Wouldn't be without it as we go to some very remote places and solo as well.

Sorry but I can't help with solar stuff. Don't run any.

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Reply By: SDG - Wednesday, Nov 06, 2013 at 21:04

Wednesday, Nov 06, 2013 at 21:04
Any reflection/glare coming off these? Could be an issue having this occur in front of your eyes while driving.
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Reply By: Ross M - Wednesday, Nov 06, 2013 at 21:06

Wednesday, Nov 06, 2013 at 21:06
You won't like the sun glare from panels on the bonnet. The gas struts may not cope either or you won't be able to lift the bonnet easily. Get the missus to do it.

Possibly won't comply with crash regs either. Will they have crumple zones too?

If 65w panel is ok for the Tvan you mustn't have much running off it's battery.

A 40L Engel only used as a fridge will use at least two amps while running and if in a hot Tvan in 30 degree ambient it will run almost all the time.
A 65 w panel will give about 4A max and only in good sun for the time of the good sun.
The 2amps for most of the day is at least 36ah use from fridge so to keep it all going and keep the battery charged you will need 9 hrs of 4A just for the fridge alone.

Best you have extra panels or an Anderson to the vehicle for the top up.

Velcro? I know we used to use 100mph tape, not sure it you can get 100kmh Velcro though. It is hard to see through broken solar panels which are suddenly plastered on the windscreen.

There are some thoughts after doing some recent testing and run times on a very well insulated (3 times more insulation than just a bag) 40L Engel with 3 very active internal fans in 30 degree heat.

Ross M
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Follow Up By: Member - Phil G (SA) - Wednesday, Nov 06, 2013 at 21:49

Wednesday, Nov 06, 2013 at 21:49
Gday Ross,
Yeah I expect glare will be an issue. The other option with mounting is on the roof in front of the roofrails/roofrack, but only useful if no Kayak. With Velcro, it is all movable! Might be able to have it on the bonnet when remote and move it up to the roof for the highway - just thinking it through now. Yeah, it might lift on the highway - at least you'd see it on the bonnet! Its something I'd check.

But don't underestimate the genuine Velcro. Its amazing stuff which I've used for many years to hold all sorts of stuff together. Its also great for electronics because it dampens the vibrations. Buy some and see how strong it is! It holds almost every accessory I have! And I like to be be able to restore a vehicle to original condition when I sell it, so sticky Velcro is removable when the time comes.

TVan has a 100Ah AGM that only runs lights, pump, rechargers and a laptop for the odd movie, so not a lot of Ah. 65W easily copes and keeps the voltage above 13V.

Vehicle has single Engel as the main consumer off a 100Ah marine battery, so thinking an 80W panel will keep it going without too many issues. We travel in winter so engel rarely cycles through the night. You mentioned insulation - I also have an older Engel which I insulated with 10mm high density foam around the front, sides and underneath and added a 12V fan that comes on when it cycles - it's pretty good - still pulls 5A when cycling but doesn't cycle as much. The newer engel is stock standard - no bag but "sort of" insulated in my storage system but only pulls 2.8A when cycling. If I was worried about how much power it was using I'd insulate it as well, but so far haven't seen the need.
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Reply By: Member - LeighW - Thursday, Nov 07, 2013 at 09:01

Thursday, Nov 07, 2013 at 09:01
The alternator probably has around 80A in reserve, that's 1136 Watts at 14.2V, a lot of solar panels!

As already pointed out no sun no power, as for the DMAX, fitting a booster diode fixes the low charge voltage and then a simple VSR can be used.


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Follow Up By: Member - LeighW - Thursday, Nov 07, 2013 at 09:04

Thursday, Nov 07, 2013 at 09:04
Forgot to add, solar panels aren't very efficient when covered in dust, so if your intending to mount permanently on a vehicle I suggest you mount them where they can be easily accessed for cleaning.

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Follow Up By: Member - Phil G (SA) - Thursday, Nov 07, 2013 at 09:37

Thursday, Nov 07, 2013 at 09:37
Gday Leigh,
the 2012+ DMax (unlike the previous model) has the "Variable Voltage Alternator". According to people such as TJM (click link for their description) the voltage can vary from 12.3 up to 15V depending on driving conditions, so upsizing with a diode is not a solution for my mate.

With the solar panel I was thinking of having the best of both worlds - a simple Redarc isolator under the bonnet to give the big amps when the battery is down, and the regulated solar panel to top it up to 14.4V. If I mount the solar panel permanently, then it requires zero input from me - don't have to pack/unpack or turn anything on or off. Like you say, just have to clean it off occasionally.
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Follow Up By: Member - Scooby (WA) - Thursday, Nov 07, 2013 at 10:01

Thursday, Nov 07, 2013 at 10:01
Hi Phil G',
What TJM is saying is incorrect. My late 2012 DMax consistently charges at 14.2v, it does not vary between 12.3 and 15V.
This is measured by my Scangauge 2.
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Follow Up By: Member - LeighW - Thursday, Nov 07, 2013 at 12:53

Thursday, Nov 07, 2013 at 12:53
Hi Phil,

As you can see above opinions differ but have had similar feedback to what your saying for models 2012 on. The mazda BT50 was similar when they first came out I seem to recall reading somewhere that the dealer has the ability to turn of the smart management function in them.

Might be worth seeing if the new DMAX has a similar setting in the engine management system?


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Reply By: Penchy - Thursday, Nov 07, 2013 at 09:08

Thursday, Nov 07, 2013 at 09:08
If you have a roof rack, why not mount them UNDER that? No risk of flying off at speed - better options for securely mounting. May lose some light through the mesh, and of course will only work when the rack is empty (mine usually is when at camp).
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Follow Up By: Member - Phil G (SA) - Thursday, Nov 07, 2013 at 09:24

Thursday, Nov 07, 2013 at 09:24
Gday Penchy,
Good thought that I may yet go with. My roofrack is very low to the roof - Its a mesh platform that I built that slots into the roofrails. I could stick a panel to the roof under the rack - might not work much with the kayak on though. The mesh is 100x100x5 so wouldn't be an issue.
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Follow Up By: The Landy - Thursday, Nov 07, 2013 at 09:46

Thursday, Nov 07, 2013 at 09:46
If the panel is obstructed (something over the top of it) it may not work...might be worth checking.
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Reply By: Member - wicket - Thursday, Nov 07, 2013 at 09:35

Thursday, Nov 07, 2013 at 09:35
One thing I've noticed with these flexible panels is the warranty period, much less than a conventional panel, most of them only seem to be 1 or 2 years, makes me wonder how good they really are.
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Follow Up By: Member - Phil G (SA) - Thursday, Nov 07, 2013 at 18:37

Thursday, Nov 07, 2013 at 18:37
Thanks Wicket - good point.
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Reply By: D-Jack - Thursday, Nov 07, 2013 at 16:58

Thursday, Nov 07, 2013 at 16:58
You own $70000 car (new) and want to save $200 bucks on the auxillary battery setup?? ??????The Velcro may hold but the glue that sticks it to the bonnet wont with the heat. 80W is not enough to rely on running a fridge, not to mention the other accessories you may want to run from it. Glare will be unbearable at certain sun angles even with sunnies. Will be a blinder for other drivers with the potential to cause accidents and that alone should be enough to deter you. The panel will be way to hot to work near its peak effectiveness (the part of the bonnet with the sun on it will transfer heat to underneath, as well as the direct sun will make it too hot to work well. There's a reason why 99% of 4wders do things the way they do with their batteries. Not a good idea, although there's no harm in challenging the majority there is harm in rejecting sound logic and argument!
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Follow Up By: Member - Phil G (SA) - Thursday, Nov 07, 2013 at 18:22

Thursday, Nov 07, 2013 at 18:22
Hey...It was a $90k car :-)) And I can assure you this is an excuse to spend more money :-)
I'll skip the middle bit.
I've installed and used a heap of aux battery systems over the past 35 years. Just tossing up something a bit different after my mate told me what he was doing with his Dmax. I like to be unconventional.
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Reply By: Member - Phil G (SA) - Thursday, Nov 07, 2013 at 19:00

Thursday, Nov 07, 2013 at 19:00
Thanks everyone for your thoughts.
I expect I'll probably get a flexible panel and install it on the roof - either under the roofrack or forward of the roofrack - the kayak doesn't get used that often. Yeah installing one on the bonnet might stand out like a sore thumb.
I'll keep the alternator charging as well - have the Ctek D250S so all I really need to do is add the panel.

Thanks for all your input.
AnswerID: 521052

Follow Up By: Bob Y. - Qld - Saturday, Nov 09, 2013 at 21:54

Saturday, Nov 09, 2013 at 21:54

Don't know if you remember back in the early days of EO, well early 2000's anyway.

Couple of members had roof rack mounted panels, one bloke had 2 at front of his rack, one on top of the other, and when parked the lower one was extended out over the bonnet, providing some extra shade, and being supported by a brace off the bullbar.

The second bloke also had 2 panels, side by side, and secured to the rack with lockable window locks. When parked, he could unlock either side and tilt the panels for optimum performance. Seem to recall they both posted photos of the set-ups, so they may be hidden deep in the archives?


Seen it all, Done it all.
Can't remember most of it.

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Follow Up By: Member - Phil G (SA) - Saturday, Nov 09, 2013 at 23:35

Saturday, Nov 09, 2013 at 23:35
Gday Bob,
Yeah - rings some bells!!
I have a set of folding panels - that you have to carry in the car, have to be setup, moved around and are very easily flogged. I was just thinking of using the flexible ones instead and mounting them somewhere where I didn't have to lift a finger - just set and forget, like the panel on the roof of the Tvan. My mate with the DMax might want to do the tilting trick though, so good thought.

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Reply By: The Bantam - Friday, Nov 08, 2013 at 09:24

Friday, Nov 08, 2013 at 09:24
I'm not sure how serious Phil G is, but full points for inovative thinking.


A few issues.

The calculations have been dome on several ocasions and it is generally agreed that the absolute minumim for long term reliability running a 40 litre fridge stand alone solar is 160 to 180 watts of solar pannels and 100Ah of battery....and that is pushing ya luck in infavorable conditions or with poor fridge discipline.

If you obscure only part of a solar pannel, this can considerably reduce its output......obscure certain parts of certain pannels and it can reduce the output to bugger all.

Yes temperature is a dramatic performance reducer in both solar pannels and batteries.....so getting both as far away from the engine as possible is a good idea.

As far as mounting on the bonnet........from a practicality point of view......if you had a ladrover with a flat bonnet it would be more realistic than any vehicle with a curved body.
Then there are all the Australian design rule issues to deal with.

All that said, in the last few years ,solar has become very much more practical and ya have to ask yaself why more vans and tourong 4wds are not wall to wall across their roof with solar panels

Back when I got interested in solar, a 4 foot x 2 foot pannel was outputting about 6 watts....ya had to have a lot of area to do anything usefull.....these days a pannel that size is putting out over 10 times the output......combine that with the leverage that LED technology is giving us in lighting the whole solar charged battery thing is getting very practical and the need to charge the van off the car alternator or maons power is rapidly becomming unnecessary.

Hell even the TV is drawing less power.
Ya old 15 inch CRT telly drew about 300- 400 watts, now a 32 inch led/lcd flat screen with a built in DVD draws only 120 watts, a 15 inch as little as 60watts...and runs 12 volts native.
So even watching telly solar powered is more viable.

AnswerID: 521090

Follow Up By: Member - Phil G (SA) - Saturday, Nov 09, 2013 at 23:53

Saturday, Nov 09, 2013 at 23:53
Gday Bantam,
Yeah...not deadly serious - just thinking of other options with the flexible alternatives.
I bought my first solar panel last year - was an alternator diehard until then! I like it its just set and forget, so moving portable panels around to follow the sun is a pain.

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Follow Up By: The Bantam - Sunday, Nov 10, 2013 at 19:24

Sunday, Nov 10, 2013 at 19:24
Phill mate things that would have seemed rediculous only a few years ago and now either practical or on the verge of being practical.

On the matter of hook and loop tape.......there is no such thing as "Velcro" according to the companie's intelectual property document.

Not too long ago I was a Velcro distributor......I no longer have a commercial interest.

The right grade of good quality hook/loop tape for the application and the amount of hold can be incredible.

many people would not realise the modern aircraft have kilometers of Velcro products holding stuff together...and not just upholstery.
Velcro make hook loop products in combinations of stanless steel, brass and nomex for the aerospace industry.....expensive and not available to the general retail client...but it does exist.

One of the big advantages of hook and loop fasteners is they are uneffected by vibration.....in fact under certain circumstances vibration actually increses the bond...because the hooks wiggle deeper into the loop.


Anybody serioulsy looking at velcro type attachment methods, should consult their local cpmpany rep.....Velcro or alternative

When I was in the game, Velcro alone used to manufacture at least 5 grades of adhesive that was factory applied to their product.
In addition to their general purpose adhesive, they had products that where more tolerant to water and heat.

One of the things we where drummed on by the reps was getting the right adhesive for the substrate and correct surface preparation methods.

The original patents on the basic hook and loop products have lapsed some time ago and there are many other companiies making hook and loop fasteners.....in a wide variety of quality and performance....
This is why the Velcro companies are so red hot on trademark issues....
Velcro themselves make a down grade budjet product under another name.

If you are looking for performance in a hook loop product make sure you get a quality product that will perform to spec and not just the cheapest thing that comes to hand.

A good hook/ loop product will be fully engineering speced.

Do that and you will be stunned at what can be held by hook and loop fasteners.

So the idea of velcro as a fastener for solar pannels may have been posted in jest......but done right may certainly be viable.

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Reply By: Member - Boobook - Sunday, Nov 10, 2013 at 06:54

Sunday, Nov 10, 2013 at 06:54
Phil, I recently added 2 flexible 80W panels on the rear hatch door of my Tvan. They are attached with Velcro and can be removed and used as portable panels. The rear deck folds up and covers them as a great security bonus.

So far I have just used then in place and with the existing 115w of fixed panel on the roof gives me about 275W. They weigh about 2kg each and are about 2mm thick, a lot better than my old framed 80W panels at about 13kg each. They seem a little more shade tolerant too. The second photo shows them in the shade and on an overcast day and I was still pulling about 2A into a nearly full battery. I am very happy with that. I have seen up to about 14A so far, but I have only been away once since I installed them and that was shady too.

I also have a 4m thick Anderson extension lead so the camper charges the car which works well. That may be an option for your friend. There are more details on the Track Trailer forum.
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Follow Up By: Member - Boobook - Sunday, Nov 10, 2013 at 06:57

Sunday, Nov 10, 2013 at 06:57
oops, that Anderson extension lead is 4m Long AND thick. 4 meters thick would be going a little overboard, even for me.
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Follow Up By: Member - Phil G (SA) - Sunday, Nov 10, 2013 at 09:59

Sunday, Nov 10, 2013 at 09:59
Gday Tony,
I followed your writeup on the Tvan forum. I confess to being inspired by your great use of the flexible panels!

But my Tvan is fine with the 65W panel I put on the roof (no fridge in the Tvan). Really thinking of something that is permanently mounted on the vehicle - so I never have to get it out or set it up. But I still want to be able to carry a double kayak and a bag of lifejackets and seats on the roofrack.

It's great to find another believer in Velcro! But you've got me thinking, that I could just store them away and lay them on the bonnet, roof or wherever as required. Minimal setup required and carrying an extra 4kg of flexible panels is a better option than the 13kgs of bulky folding panels I've got at present.

I've also got a charge lead like yours.
But there's another option is well that I've thought about getting to transfer battery power from the Tvan to the car (or to recharge any flat battery). Its called a Swallow charger and is used by the electric model people. I'd use it as a 6A charger (on the SLA setting) - powered by the Tvan battery to charge the Landcruiser battery. The advantage would be that I could run it overnight, and leave the Tvan solar to do its stuff during the day. But the device itself is one of the best pieces of electric equipment I've ever seen - can use it to recharge any sort of rechargeable battery incl Lipo and also works as a discharger, and can operate off 11-15V or 240V.Link Here. And a disclaimer - my son is the sales manager for the company!

Thanks for the ideas,
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Follow Up By: Member - wicket - Sunday, Nov 10, 2013 at 16:35

Sunday, Nov 10, 2013 at 16:35

Just wondering where you got those panels ?
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Follow Up By: Member - Boobook - Sunday, Nov 10, 2013 at 17:33

Sunday, Nov 10, 2013 at 17:33
Wicket, I just got them on ebay here

I simply picked these because their dimensions were the largest that would fit on the rear hatch on the Tvan. They seem pretty good and were shipped from Sydney.

Not bad value at $380 plus $40 shipping.
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Follow Up By: Member - wicket - Sunday, Nov 10, 2013 at 17:47

Sunday, Nov 10, 2013 at 17:47
Just found your write up on the Tvan site........these panels are about the only flexible panel that seems to give a decent warranty. So will keep them in mind for a little project that I am planning
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Follow Up By: Member - wicket - Monday, Nov 11, 2013 at 09:09

Monday, Nov 11, 2013 at 09:09
Looking at those cables coming from the junction box they look a bit weedy and I'd probably change them so I'm wondering how accessible that junction box is, can it be opened or is it permanently sealed ?
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Follow Up By: Member - Boobook - Monday, Nov 11, 2013 at 09:49

Monday, Nov 11, 2013 at 09:49
I am not sure which junction box you refer to. I don't have any.


If you are talking about the red blocks, they are pairs of red 50A Anderson connectors so I can unplug the panels and use an extension lead when I move the them. The red ones won't fit into standard grey ones and I have standardised on them for all my unregulated solar connections.

Also the 150mm of cables from the panel to the Anderson is what was supplied with the panels on one side, and twin 5mm automotive cable into the hatch roof and to the Regulator, they are covered in white heatshrink. When I use the extension leads, they are 8 B&S.

Am I missing something? The cables are more than up to the task of the 5 Amps available from each panel.

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Follow Up By: Member - wicket - Monday, Nov 11, 2013 at 10:10

Monday, Nov 11, 2013 at 10:10
I am referring to the boxe on the panels, the cable that is joined and supplied is 1.5mm2 which I'd like to change , is that feasible?
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Follow Up By: Member - Boobook - Monday, Nov 11, 2013 at 10:21

Monday, Nov 11, 2013 at 10:21
Kind of changeable wicket.

It opens up easily and you can get access to change over the wires to solder tabs, however it's all covered in silicon to waterproof it. I wanted to put in series Schottky diodes to prevent back flow if shaded but gave up and put them elsewhere.

A bit of hacking and you could get to the solder tabs however if you have concerns I would just limit the length of the supplied cable as I did. The voltage drop at 4A over a short length would be almost immeasurable.

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Follow Up By: Member - wicket - Monday, Nov 11, 2013 at 10:34

Monday, Nov 11, 2013 at 10:34
Ok thanks, the ad on the website says the box is customisable so I'm not sure what that meant.
My issue is I'm looking at about 8 or 10 of these panels for the top of a motorhome, from the 1st to last panel in about 3.5 mtrs before I start the cable to the reg so am thinking the supplied cables might be a bit underweight.
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Follow Up By: Member - wicket - Monday, Nov 11, 2013 at 11:12

Monday, Nov 11, 2013 at 11:12
oops no need to answer have just realized that these should be ok as the run for each will only be very short but will beef up the cable joining them to the mc y/t types joiners connecting cable
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Reply By: Member - Bill D - Thursday, Nov 28, 2013 at 22:39

Thursday, Nov 28, 2013 at 22:39
It's my DMax Phil is talking about. I see the discussion has gone into various areas, especially flexible vs rigid panels, but for the record, I'll just list what I've actually bought. The inspiration for all this was:

1. Worries about possible difficulties charging off a smart alternator
2. Worries about the cost of possibly two DC-DC chargers (one for the aux battery in the DMax and one for the caravan batteries)
3. Phil's experience of adequate charging on his Tvan with solar panel only
4. A trip from Adelaide to Sydney towing our new van with two panels on the roof - both AGM batteries stayed pretty full without any connection to the tug (the fridge is a Waeco compressor upright, not one of the dreaded fifteen amp 3-way fridges).

What I've bought for the ute canopy (but won't be installed until I get rid of the lurgi):

100AH AGM battery, donated by Phil
125W rigid solar panel (Bit Deals - well under $200)
20A regulator
8 B&S tinned twin cable
plus we already have a folding 120W panel for extra power on cloudy days and to allow parking in the shade on sunny days.

I'm expecting this gear to run my Waeco CF50 car fridge, canopy LEDs, chargers, etc

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