AnswerID: 114236 Submitted: Friday, Jun 03, 2005 at 14:42
V8troopie
replied:
Matthew, the best answer anybody could give you is "it depends".
Seriously, there are far too many variables for a straight answer.
you have to consider the sunshine hours where you travel, the capacity of your battery, the length of stay, wether you run the
Waeco as a
fridge or a freezer, and on and on.
There is a lot of info on the net about your dilemma but you still have to come up with a Amp hour figure ( number of amps your
fridge & lights draw times number of hours it needs running per 24h) per day to get you to the starting block.
Then you find out how many solar hours are available at the time of the year where you are travelling, add a big margin for cloudy
weather and work backwards for various size panels to get a figure what number of Ah they would put back into the battery. You have to allow for charging losses here too. In case you are not familiar with charging terms, Watts = Amps x Volts. You'd use 13V for yor calculations since a battery needs at least 13v to start charging.
Or, you can try the suck it and see method and start with a 80w panel and be prepared to use alternative charging methods if you find the panel is too small. (80W is at the very low end of the scale for running a
fridge, and it would have to be placed to face the sun all the time). Be prepared to purchase an additional panel once you get an idea how what you have performs and perhaps is below expectations.
Where to get it?
Shop around!!! there are big differences in panel prices, sometimes one or the other is on 'special' at one or other retailer.
I got my last panel at a mailorder place called "Tasman energy". A 64W panel, shipped to
Perth from
Queensland was cheaper than any local supplier could offer
Do yourself a favour and also get an Ampmeter to see just how much charge you get at any moment. A multi meter would do but you'd have to disconnect wires every time you use it. Better to get a little panel meter, perhaps 0-10A size and permanently wire it into ONE lead of your charging circuit.
good luck in your
search
Klaus
Reply 3 of 18