I have 3 x 150W solar panels connected in parallel (12V system). Can I just connect more panels of any type in parallel, providing they are 12V, or are there some other specs that I should try match?

 

the panels are on the roof of a caravan, but when parked in shade obviously they don’t work, so I’d like to try adding flexible panels to plug in when needed - they can stand away from my nice shady camp spot...

 

Etienne

32 minutes ago, Etienne said:

Can I just connect more panels of any type in parallel, providing they are 12V, or are there some other specs that I should try match?

Yes, check the max volts and amps of the controller and make sure you never exceed that in the coldest temps you can experience wherever you camp.

Others can answer your second question ito what you are asking. 

Personally I would have made the array move-able, with a few extendable 10mm2 cable lengths, as a caravan under trees is always a really nice thing. Obviously the moveable frame is made unmoveable with a chain around it. 

Edited February 23, 20197 yr by Guest

Well I'd say there is a little bit more to it. First you have to check if the charge controller is PWM or MPPT.

If it is PWM controller, then your panels will be connected in parallel. You'd have to look at the maximum current each panel can provide and add them. For example, if we assume a typical 36-cell 150W panel, then this is typically around 8.3A, so three panels in parallel will push around 25A. If your charge controller is not rated for 30A or more... then you cannot do it.

If it is a MPPT controller however, then you have to look at the maximum input voltage allowed by the controller. Again, if we assume a typical 36-cell 150W panel, they will have an open circuit voltage of around 22V, so three in series puts you around 66V. Most good MPPTs can handle that much (some cheap Microcare units can't handle more than 50V though, watch out), and a higher input voltage is generally preferred when using an MPPT. The fully utilise the power of all three (450W total) you need a controller that can put out 450/12 ~= 20A. If the controller is rated for less than 20A, well then it usually won't blow up as it would in the PWM case, but you'd be wasting some of the top end.

So all in all it is a bit difficult to conclusively answer it, because we don't know what charge controller is used or what spec it has. If you have a cheap 30A PWM controller for example, adding more panels in parallel could be a bad idea.

I built some 'suite cases' using 150W solar panels for camping purposes. Add some 15m solar cable with MC4's and you can place them pretty much anywhere you like.