Thread: Mounting solar panels to a roof tray.

Originally Posted by Tank

Parking your vehicle in the sun will soon show it is not a good idea, esp. if your fridge is in it.
Make the mounting so as you can park in the shade and position your panel out in the sun, make up an extension lead, you will regret mounting it permanent to the vehicle, Regards Frank.

Could not agree more.

Originally Posted by Tank

Parking your vehicle in the sun will soon show it is not a good idea, esp. if your fridge is in it.
Make the mounting so as you can park in the shade and position your panel out in the sun, make up an extension lead, you will regret mounting it permanent to the vehicle, Regards Frank.

Not so much,

My panels permanent and with one of those $10 window vent fans fitted up I've never had any issues with leaving the vehicle in the sun.

The single 80w panel I've got mounted across the disco roof provides enough juice to the battery to extend a 2 day stop to between 3 and 5 days on an n55 size battery (standard discovery 1 battery)

According to the logger (and from memory when I've ever bothered to check it) in the regulator I've got the panel averages about 3 amps an hour into the battery/load over a 24 hour period

Originally Posted by Blknight.aus

Not so much,

My panels permanent and with one of those $10 window vent fans fitted up I've never had any issues with leaving the vehicle in the sun.

The single 80w panel I've got mounted across the disco roof provides enough juice to the battery to extend a 2 day stop to between 3 and 5 days on an n55 size battery (standard discovery 1 battery)

According to the logger (and from memory when I've ever bothered to check it) in the regulator I've got the panel averages about 3 amps an hour into the battery/load over a 24 hour period

Thanks for these and the previous comments of others.
I've thought about this a fair bit and I agree with the above. Often it's not possible to park in the shade. Having the roof panel means the system is getting charge all the time there is solar energy, so if the fridge is running its draw down from the battery is being replaced.
Since the vehicle spends most of its time away from home out in the sun, that's good. For example, if I park outside at a shopping centre or some other place the battery will be charged to replace anything drawn by the fridge. Plus, the starting battery will also be charged.
I will actually be able to remove the panel from the vehicle by unscrewing four mounts, so I could put it out in the sun with the vehicle in the shade, although it might be a bit fiddly doing that.
I do also have a separate folding panel 80 watts I could plug into an Anderson plug already connected to the second battery.
So, I will have the best of both worlds.

if you're regularly driving to the shops the panel is doing very little for you as most of the charge will be coming from the alternator (assuming you have a good DBS)

IF I had the option to do my setup again I would have put in a set of pin lock multiflex hinges to mount the panel so that in the mornings and evenings If I wanted to get a bit more out of the panel changing its angle would have been as simple as pulling 2 pins and inserting a prop stick.

The reason I didn't is because of the profile I have for my vehicle I can still fit the disco complete with its awnings and solar panel into most carparks and getting the panel to fit in the space available in the time available just wasnt going to happen with fancy hinges.

The configuration you are proposing will not charge your batteries against a car fridges draw but if you're doing it for the reason I've done it will give you a little more time in location with a smaller battery which you then charge on the next leg of your trip.

Originally Posted by Blknight.aus

if you're regularly driving to the shops the panel is doing very little for you as most of the charge will be coming from the alternator (assuming you have a good DBS)

IF I had the option to do my setup again I would have put in a set of pin lock multiflex hinges to mount the panel so that in the mornings and evenings If I wanted to get a bit more out of the panel changing its angle would have been as simple as pulling 2 pins and inserting a prop stick.

The reason I didn't is because of the profile I have for my vehicle I can still fit the disco complete with its awnings and solar panel into most carparks and getting the panel to fit in the space available in the time available just wasnt going to happen with fancy hinges.

The configuration you are proposing will not charge your batteries against a car fridges draw but if you're doing it for the reason I've done it will give you a little more time in location with a smaller battery which you then charge on the next leg of your trip.

Thanks. I should have said more about how it will be used.
The Defender is not used for commuting, so spends most of its time under a carport with the fridge off.
When travelling I want the panel to extend the time we can stay in one place with the second fridge (a 30 litre Evakool) running, in addition to the 40 litre Engel in the camper, which has its own solar and battery.
The DBS is a Traxide unit connecting the Defender's big starting battery and a 120ah AGM in the back. The alternator is doing a good job of keeping everything charged while travelling.
Like you, I mounted the panel flat to roof racks so I can still get into many car parks.



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my Back of the napkin says that with a stock n70 for the deefer and allowing for ~100AH from the 120 battery..

you should be able to do 3 days without any sun and 4 if your panel performs on the same level as mine with both fridges running

I can do a pull up friday, stay saturday and leave sunday morning without the panel on my battery setup without the aux battery autodisconnecting

with the panel I get to monday morning BUT the aux battery disconnects early in the morning and stays that way until the panel comes up or I drive out.

If I stretch monday I usually have to be gone by about 1600 when the panels output isnt enough to sustain the fridge.

You 80 w panel wont give you enough to run the 2 fridges at once when the aux battery is down and the Traxide has disconnected.


Thats using moderatly generous numbers in terms of expected draw and my average numbers for panel input to the system to account for a little extra load like phone chargers some led lighting and a radio on or about 2 hours of one of those 16 inch tv/dvd player units that run direct on 12v.

If you want to see the nuts and bolts of my setup search for lecturing a tdi300 using my username as the thread starter.

Thanks for that. I didn't explain properly that the other fridge is in the camper trailer with a separate 105ah AGM and I plug an 80 watt folding panel into it. So there are two fridges totalling 70 litres, two solars totalling 160 watts and two batteries totalling 225ah, plus a bit from the starting battery. So, while that won't keep us going indefinitely, I reckon we will be able to camp for a week on Straddie at Christmas OK. Am I right?

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Here's my 80 watt panel now mounted to the roof tray with some custom brackets knocked up by a welder mate out of offcuts. They are over-engineered but that's OK.
Looking forward to trying it out camping at Christmas.

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