Can I use two solar charge controllers to charge the same bank?

[Kelpie]

New (to us) boat has an existing charging system with a controller that accepts up to 160w of solar.
We want to increase this to around 400w total, but rather than get rid of the quite nice Marlec unit already installed, can we add a second charge controller alongside it, and have them both charging the same battery bank(s)?
The Marlec is also connected to a wind gen so I would prefer to leave that whole system as-is.

 

[wizard]

Well, I have done what you propose for years with no problem. There might be circumstances where if using different types of chargers ie pwm or mppt might cause one not to be charging at the same time. But in practice it is not noticeable in the overall scheme of things.

 

[RichardS]

Presumably you intend to put the entire 400W of solar through the new controller and leave the Marlec to manage just the wind gen because the Marlec cannot take 400W?

That will work OK.

Richard

 

[PaulRainbow]

Having two charging sources can cause issues, depending on the controllers and the charging regime to which they are set. For instance, early in the morning when the Sun starts to shine there is a strong breeze and the wind gen' is charging the batteries nicely, the solar controller wakes up and sees the voltage from the wind gen' controller and thinks the batteries are charged, so it doesn't start.

All you can really do is to fit the solar controller and monitor what happens, you may need to adjust some settings, so fit a decent controller that can be configured. It's usually the case that two sources work better together when the charging regime of both controllers is as close to identical as possible.

 

[Kelpie]

Thanks for the replies.
This is the Marlec controller in question: https://www.marlec.co.uk/product/hrdi-controller/?v=79cba1185463

It's already hooked up to a Rutland wind gen, and a small solar panel. As I understand it, it can take 160w of solar in addition to the wind gen.

My plan is to max out this charge controller, and add a second controller for further solar panels. Of course I could just make the second controller bigger, to handle all of the solar by itself, but that presumably means spending a bit more money.

 

[Heckler]

Thanks for the replies.
This is the Marlec controller in question: https://www.marlec.co.uk/product/hrdi-controller/?v=79cba1185463

It's already hooked up to a Rutland wind gen, and a small solar panel. As I understand it, it can take 160w of solar in addition to the wind gen.

My plan is to max out this charge controller, and add a second controller for further solar panels. Of course I could just make the second controller bigger, to handle all of the solar by itself, but that presumably means spending a bit more money.

As Paul said, things can happen! Its all in the sensing! I had a weird situation in my previous boat. solar putting max in, Sterling Alternator booster saying, ah, full charge and shutting down alternator and so I then get weird situation of VP panel charge light coming on and alarm sounding that alternator is not charging!

 

[RichardS]

Having read Paul and Stu's thoughts I'll change my response to "it might work OK ... but it might not".

Richard

 

[john_q]

As Paul said, things can happen! Its all in the sensing! I had a weird situation in my previous boat. solar putting max in, Sterling Alternator booster saying, ah, full charge and shutting down alternator and so I then get weird situation of VP panel charge light coming on and alarm sounding that alternator is not charging!

I have this situation as well so now turn the solars off whilst motoring.

I have been thinking about splitting my 400 watts of solar into 2 banks Port and starboard to (hopefully) reduce the effects of shading

 

[ip485]

We have been around this one before.

Give it a try, it cant do any harm.

I run two chargers, a solar controller and the alternator often at the same time and / or in combination and dont have any issues. My systems just dont "see" the charge from the other sources and the combination works very well.

 

[Graham376]

For 10 years, I've had a small panel regulated by the Aerogen reg and larger panels via an MPPT, both regs charging the same batteries with no problems. Have just virtually doubled panel size so, until I get back with larger reg, have 2 x small mppts in parallel charging same batteries, Aerogen removed but small panel still temporarily connected to that reg.

 

[Tim Good]

Fornwhat its worth adding to other replies, I've got a an MPPT with 360w of series panels alongside a 60w panel on a standard controller. They seem to work fine together, but I have noticed that the 60w controller seems to go into float when the batteries are nearly full.

The 60w is on the Coach roof with a long cable to roam around at anchor.

 

[geem]

We run six different charge controllers. There is the standard alternator on the engine, the wind/water generator with its own regulator, the MPPT solar reg on 340w of solar just dedicated to the domestic battery bank, the Sterling shorepower charger run from the diesel genset, the second shore power charger also run from the genset and the PWM regulator running a 40w panel that has dual output to both engine and domestic banks.
The sensing of the various regulators are all different. The Sterling shore power charger is set to the highest voltage such that as the battries approach full charge, all other regulators start to shut down assuming the batteries are charged. Its not a problem since the shore power charger belts out 60amps. In reality, if my batteries are so discharged then all operational regulators are charging until the batteries get charged sufficiently that the various regulators start to cascade off assuming full batteries. I don't find it a problem.