Thread: Multiple solar panels

Originally Posted by Blknight.aus

not quite right but near enough the wattage is at the panels nominated output voltage not its open circut voltage...

the panel should state a voltage (12 or 13.8 depending on manufacturer) then devide the wattage by that voltage.

Id work it on the 13.8v number for your expected charging output but the 12v number when picking your regulator...

I wouldnt run the 60a regulator for that setup one of the cheapy blackbox regulators from jaycar will handle it nicely.

Actually, it is not even that simple - the rated power of solar panels is the maximum power that they are capable of delivering in a standard sunlight flux at standard temperature. It will not usually be at 13.8 or 12v, or at the open circuit voltage - as more current is drawn, the voltage falls from the open circuit voltage, and the maximum of volts x amps is usually somewhere around 14-15v.

So in real life, the actual charging current you get depends heavily on the state of charge of your batteries (and current is what matters, not power). The output also depends on temperature and amount of sunlight. Since standard temperature (I think most if not all are rated at 20 degrees) is lower than what you have most places and most times in Australia when it is sunny, and output falls with increase in temperature, you will usually get less than you expect, even if your orientation is exact.

On the other hand, scattered cloud or other reflecting surroundings can greatly increase the amount of light falling on the panels. Combine low temperatures, clear slies and a lot of reflecting surroundings (i.e. snow) and you can get up to double rated output, and I have heard of several cases of people cooking regulators that should have been high enough rating in these conditions.

John

As an add-on to this thread.... I started it so I'll chose to Hi-jack it!

My panels are the anomorphic type. Just how strong are they?

I was thinking to mount then underneath the roofrack on a slide out tray so when I was parked up I could slide them out, plug them in and then angle them to start the trickle charging etc.
The panels construction is two sheets of laminated glass with the panel sandwhiched inbetween.
Would these be strong enough for the abuse given by driving down washboard gatch tracks etc? or do we think that they might break under their own weight?

Who has got panels perminently mounted on the roof of their trucks or is it best to pack them away safely and delpoy them when they are needed?

Thx,

S.

Just bumping this to the top again!

Anyone care to comment?

Thx.

Hi Streaky, Dinty has his mounted on the sloping roof above the Driver and has had no problems as far as I know.He has a 110. Cheers, 130man.