Multiple Output MPPT

[olaf hart]

I think I have inadvertently done this by connecting my solar panel to the start battery when I already have the standard Bluesea ACR and on/off power switch, my ACR automatically switches to the house battery once the voltage gets over the threshold level.

Not sure if this is a good idea or not, but no issues to date. I only use the solar to trickle charge the batteries, a 20 watt panel on 300ah total AGM storage.

[noelex 77]

Originally Posted by Maine Sail

With no voltage present on the input stud, the solar controller can't boot-up.

Thaks for the information. I had not thought of that problem.

We used a Sterling Pro R diode splitter on our last boat, but that was on the alternator, not the solar output.

To give the start battery a complete charge we simply paralleled the start and house banks occasionally on the good solar days.

[txg]

Originally Posted by Maine Sail

MPPT performance varies widely, some are actually quite pathetic, and spend lots of time lost & looking for the power point when they should be charging. Better quality controllers use better algorithms that can track the power point much, much faster... On a constantly moving boat a fast tracking MPPT controller is important...

I would suggest focusing on choosing a fast MPPT controller, Genasun, Victron, Morningstar, Midnite, Outback etc... over a mutli-output MPPT controller. Start batteries rarely need any more than what the get from running the motor and the starting consumption is extremely low.

I agree to all of that. But anyways the Votronic controllers are fast and high-quality, not some chinese backyard junk. This is a german company that builds charge controllers for quite a long time now. And apart from beeing good controllers in general they offer a second output on top without being more expensive than let's say a victron. So what's the point of having a more complex and more expensive installation if there is a product that can do exactly what is needed (keeping a starter battery topped up) without an additional ACR?

[john61ct]

None offer an independent charge algorithm.

The ACR is not just for solar, but also mains charger, generator, alternator etc, a single connection point simplifies the design.

Votronic is indeed a great mfr, but chooses afaik not to sell into the NA market, so is support available. How do you buy them?

[Cowpoos]

Originally Posted by GTom

If your solar array is big enough, probably two controllers would be the best solution.

What Gtom said. Get another controller. In the best case setup, you would have a controller for every panel, to negate shading losses and another controller for the start battery. You will also have a ton of redundancy in having multiple controllers.

[john61ct]

Yes to 1:1 SC to panels, but wire all to House.

See #12