Two Panels, one or two controllers?

[Jabs]

I wish to fit two solar panels, probably semi flexible, self adhesive with front mounted junction boxes.

I don't want to alter the wiring on the existing system, merely use the panels to charge the batteries.

What controller or controllers should I use?

I have sufficient monitoring of battery capacity available.

One or two?
Series or parallel?
The panels could be in different light levels??

Thanks

Tony

 

[Pete7]

Tony, I have a pair of Victron MPPT controllers because it was easier than trying to run wires all around the boat. They both play nicely together. You haven't said what size of panels you are thinking, but the price of MPPT controllers has dropped in price. Additionally the latest Victrons can be connected directly to a PC giving all sorts of information and adjustment. But be warned it can be addictive.

Pete

 

[Graham376]

If panels are hard mounted and close then one controller is best. If likely one panel to be in shade then parallel, if no shade then series. If you go for Victron Smartsolar regulator, it has built in bluetooth and can be set up and monitored with any in-range suitable smartphone, tablet or PC.

 

[vyv_cox]

I have two panels, 40 and 85 watts, wired in parallel to a PWM dual bank controller. I have now had this system for more than 10 years and it works perfectly. Fridge runs 24/7 for six months of the year. Even (whisper it) with a 1-2-both-off switch.

 

[William_H]

You can only connect 2 panels in series if you use an MPPT controller. This is because the combined voltage will be max 40v under load about 34 volts. The MPPT controller transforms the voltage down to 14v needed for battery charge. (in a way which extracts best power from panels). If you have or want a simple pulse width controller (PWM) then panels must be in parallel. However if you have dual battery banks then you might want to go 2 panels 2 controllers to 2 separate batteries. A much better arrangement when and if batteries die. ol'will

 

[Stemar]

My controller is a fairly basic one, but charges two batteries from two panels wired in parallel. I have it set to charge the engine battery first, then the domestic, on the basis that a dead engine battery (unlikely, but not impossible) could be a disaster, while dim lights is rarely more than a minor incident