Monday, Oct 03, 2011 at 17:56
G'day Wayne.
I am going through the exact same dilemma right now. A few points to consider;
Mounting a
panel on the vehicle roof and wiring it to an aux battery is fine, however the
solar panel regulator will not turn 'on' and actually charge the aux battery while the vehicle is running and the aux battery is receiving charge from the alternator. Depending on the specific
solar panel regulator, and the voltage AT the battery when the alternator is providing charge basically the regulator is going to believe the battery is full and stop the
panel from providing charge to the battery. Its one or the other, not both; unless you suffer from some serious voltage drop.
Every time you stop in the sun, sure the
solar panel will try and pickup where the alternator left off but there are many variables ie. load on the battery (fridge running at the time), float voltage of the battery before it has rested from the alternators charge etc. What im getting at is if you just switch off the vehicle for 5minutes to run into a
shop, the
panel might not even start charging in the mean time as the regulator might see the battery again as being full.
To
answer question 1 specifically, despite the above there is no problem wiring the
solar panel regulator straight into the charging circuit, no need to isolate it.
With regards to question 2, as you said it really is personal preference, and picking at straws. Depending on the fridge you run and how
well it is insulated the exact results will differ but generally speaking i think its fair to say that yes, the hotter the environment the fridge / freezer is operating in, the more frequently it will run and the more power it will use.
So, depending on the size
panel you are choosing to buy it may or may not be able to replace what is being used by the fridge. If the
panel is big enough it should still do the job fine, perhaps it wont bring the battery up to near full as quick but again, still better then no
panel!
.................................
Personally, im really torn. I like the idea of mounting a
panel on the roof once its done its done! Ive just fabricated a canopy for my ute but they do take up a lot of space which may or may not be required (depending on the
panel wattage).
Another point to consider however not vital is any
panel mounted flat is going to loose some of its efficiency. Approx 10-20% depending on the conditions. (Compared with a clean
panel aimed perfectly at the sun).
The other day i went out to purchase a
panel but bailed in the end. I went out to buy a folding
panel, because 1 its less work for me to do in the lead up to our next outback adventure real, real soon! 2 I get to keep all of the space on the canopy roof free for stuff.
And as you have already mentioned, with a portable
panel the vehicle can be parked somewhat in the shade and the
panel moved around to achieve maximum performance out in the sun.
Theft of a portable unit is very real i guess, however id really like to buy a
solar panel just in case we stay an extra night somewhere. Our battery's all being
well on their own have enough capacity to do the job on their own. So if we decide to stay an extra night somewhere or arrive early one day, the portable
panel can go out, and we will remain close buy.
Now back to the other day, i had a good look at the 120W folding
panel (2x60w panels). I found it was quite a bit heavier and painful to unpack and repack then i expected. However this has more to do with the cheap bags they come with, a decent quality canvas job with a zip that went around 3 of the 4 sides would make setup / packup much easier.
So that notched up another point to a fixed mono
panel on the roof, and thus im still bloody torn what to do! Fixed
panel on the roof is also quite a bit cheaper. ie. 80w folding
panel $300/400, 80w fixed mono $160 + reg $20-50.
As our departure date gets closer i think more and more about a folding
panel, as i just buy it and chuck it in the back. One less job before going!!!
Travis.
AnswerID:
466687
Follow Up By: Member - Robert R1 (SA) - Tuesday, Oct 04, 2011 at 21:36
Tuesday, Oct 04, 2011 at 21:36
Travis,
I have my
solar panels mounted on the roof of the canopy and I find that even when I am parked in the sun, the inside of the canopy does not get very hot. I often open up the canopy doors to allow the air to flow through.
Two of my panels are hinged and are raised by gas struts. The other can be slid out and set up away from the vehicle. I don't normally bother unless things are getting desperate. If I can I park on a sllope.
Regards,
Bob
FollowupID:
740906