Solar panel controller

**nismine01** · 2nd October 2016, 10:57 AM

I am looking at putting four 250W panels on my caravan.

My (right or wrong) calculation is that there is the potential for 83 amps on a good day.

I have looked at Ebay but can not find a unit capable of handling this much power.
Do I;

1. Use multiple controllers, 1 for each or two panels feeding independently to the battery system; or;

2. Split the batteries (4) and power each with one of the panels through it's own controller then using some method connect them together to provide a large bank of power, or;

3. As #2 but draw off 1 battery at a time with switching mechanism to change to next battery when voltage is dropping on first one?

I would much prefer to have all the batteries in one bank so as to be able to handle a large load should I put one on the system.

Any clues from people in the know would be much appreciated.

Cheers and thanks in advance.

Mike

DiscoMick · 2nd October 2016, 11:16 AM

I would have thought multiple controllers and all the batteries connected, but I could be wrong.

Sent from my SM-G900I using AULRO mobile app

**spudboy** · 2nd October 2016, 12:45 PM

I run 6 x 100w panels on the roof of my truck through a GSL 30A MPPT controller with no problems.

I have 3 AGM batteries in a single bank.

They do a 60A model: GSL Electronics : MPPT 60-1 / MPPT 60-2

Made in Australia. Excellent quality. Reasonable price.

**loanrangie** · 2nd October 2016, 12:47 PM

What the hell do you need 1000w of power for ?

**LandyAndy** · 2nd October 2016, 02:37 PM

On a dull day he would still make power I guess.Have camped on the south coast of WA and not seen the sun for a week.Panels still charge but at a much lower rate.
Andrew

**sierrafery** · 2nd October 2016, 02:41 PM

Originally Posted by nismine01

I am looking at putting four 250W panels on my caravan.

My (right or wrong) calculation is that there is the potential for 83 amps on a good day.

....
Cheers and thanks in advance.

Mike

IMO you can't calculate this way, there is a thing with those solar pannels named "Approximate Peak Sun Hours (PSH)" and that's what is considered that 250W but this is very relative cos when let's say the sun is strong and gives maximum light to the pannel the pannel gets hot and then the output rating can drop even with 25% and when the sun is not 100% shining the ouput is not at max rating

the gist with those pannels is that the battery will not discharge at all while the pannels are giving higher or equal output with the load connected...so if you connect all the batteries in one bank and the pannel's output will be lower than the load that whole bank will discharge and you'll have no backup if you see what i mean. IMO set a smart controller as to split the pannel's output between batteries and the load and keep the batteries in two banks

**dero** · 2nd October 2016, 03:55 PM

With larger systems , ie house hold , the panels are connected in such a way that the voltage increases rather than the amps . Lots of amps equals large cables etc.
Check out series and parrallel circuits , and the voltage and current ratings of controllers .

**bee utey** · 2nd October 2016, 05:43 PM

My guess is that the 250W panels will be nominally 24V panels with a maximum power output current of around 8 amps at around 34V terminal voltage. Once you have the actual specs of the panels then choose MPPT charge controllers to match. Feeding a 12V system you'll need two of these, one for each pair of panels in series:

Esmart 40A LCD MPPT Solar Charge Controller Battery Auto 12V 24V 48V Regulator | eBay

A 24V battery would only need one controller of that type.

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