Thread: Multiple solar panels

Ive always felt that in the case of multiple panels all panels should have their own dedicated regulator but you can simply parralel them into one bigger regulator that can handle the combined output of all panels involved, this is usually the cheapest way.

the downside is its not the most effecient way, if one panel is in the shade it will draw down the output of the other panels but if its only for occasional use then that shouldnt be a problem.

Provided all panels are the same, and provided that they are equipped with a blocking diode (this prevents a shaded panel from draining power from the others, and most panels have them), simply wiring them in parallel is the best way. The only catch is to ensure that the regulator is adequate capacity, but with only two panels you will have trouble finding a regulator with insufficient capacity.

Even if the panels are not identical, provided they are the same number of cells, separate regulators are not needed.

John

Two 12 Watt panels will only supply 2 Amps charge current in the best of sunlight conditions. Your fridge will probably draw about 5 Amps while it is running. My work vehicle is equipped with two 68W panels to supply a 60 lt Trailblazer. This is enough in winter in Cape York, where I often work, but come the summer temperatures and cloud cover, the battery needs a charge from the vehicle or generator.

Thanks for the inputs.

I am very much aware that these two small 12 watt panels won't be enough to run even the fridge (40lt Engal) unassisted...I just want to trickle charge my aux battery throughout the day and perhaps then run the engine for 30 minutes later in the day for a faster battery top up.

My regulators will handle 60amps each and I have two of them. It's not the ideal solution but it should at least prolong the battery life between charginjg from the alternator. Both panels have reverse blocking diodes & my aux battery is an Optima yellow top deep cycle.

They are selling the Pirana distributed BP crystaline panels here in Dubai now...but at over USD1000 for a 60 watt unit I'll make do with what I have thanks.

As said before as long as your regulator can handle the current you should be OK.

Assuming the terminal voltage on your 12 Watt panels in full sun is around 18V ( typical ), the max current they will both deliver is ~ 1.5 Amps so a reg. rated at 60 Amp is going to handle that no problem.

A simple check is to hook it all up to some batteries and leave it for a while with the panels in the sun and the regulator in the shade. The regulator could get warm, but should not get too hot to touch.

I get about 1.3 amps total for both panels but I could be wrong?

Originally Posted by harro

I get about 1.3 amps total for both panels but I could be wrong?

You might be right too, how did you work it out ?

Originally Posted by waynep

You might be right too, how did you work it out ?

Divide the closed circuit voltage (in a solar panel about 17 to 18 volts)
into total rated wattage ( in this case 2x 12=24)

Plus 12 watt solar panels are rated to between .6 and .7 of an amp

I hope I'm right, thats the formula I used to set up my system.