MPPT Solar 12v input - 48 output?

[andreas.mehlin]

I´m looking for a regulator that can have a lower input than output. Does those exist? Or do I have to serie connect the panels to 48V?

[44'cruisingcat]

Google "solar boost controller".

There are controllers which can charge batteries of higher voltage than the panel's output, but not sure if they can quadruple it.

[john61ct]

You need a regular controller to a starter, then a 12V to 48V DCDC controller to House, maybe Sterling/Promariner make such.

[snaptwo]

Short answer - yes, you can get a device called a "boost converter". These are not overly commonly made, but are available. The reason you see little of them is they are, to a man (or in today's vernacular "to an androgenous object) horribly inefficient. We are talking circa 70% efficient for a good one, compared to a step down or "buck" converter that can get to the high ninety percent efficiency in the hands of a good designer. Without doubt in my mind if you are buying solar panels you need to be buying higher voltage, more efficient panels and stepping them down - maintaining as much efficiency as possible and reducing your costs, capital outlay and maximizing return, to the greatest extent you can.....

[john61ct]

No you really want charger intelligence, not just a straight power supply, unless you're planning to babysit every charge cycle.

I had a quick look among DCDC charger manufacturer, 24 or 36V yes, but not 48.

You'll need to either use a solar controller designed to output 48, e.g Morningstar TS-60 TriStar, or set up switches to take a bank offline for charging and change serial connections to parallel. At high amps this latter idea would be pricey, former is better.

[andreas.mehlin]

I found a couple of solar charger to step up the voltage
GSL Electronics : BMPPT 800

Genasun - but this one only takes 105W if I have a 12v panel and want to output 48v. 99% efficiency

[snaptwo]

Originally Posted by andreas.mehlin

I found a couple of solar charger to step up the voltage
GSL Electronics : BMPPT 800

Genasun - but this one only takes 105W if I have a 12v panel and want to output 48v. 99% efficiency

And I believe in Leprachauns and pots of gold too. Yes, the converter no doubt converts up (boost) but the 99% efficiency is pure garbage. Ask for a set of switching efficiency curves, and if they are honest you will find that you should get a solid low 80% average across any useable range. For units that are tailored to a specific load and input profile we can get high 80%’s. Step down on the other hand we can get high ninties (read 95 to 97 percent) if we are careful over selected ranges. Reading other parts of the Genasun literature should be warning enough - “using industry leading ceramic” “no liquid filled devices” “first to last longer than a year” etc., etc. I am sure their unit does what it says, its just they are stretching the truth. Once you have the data sheet (and note also they speak of the unit being used for LiPO4 type cells I think) and inspect that then if the device matches the data sheet you will know what you are getting. Again I can only commend you to buy a solar panel to match your use - 48VDC nominal service with an inexpensive MMPT controller matched to your load.

[john61ct]

Not saying they are angels, but Genasun does have a rep for making top-heavy stuff.

There is likely a very specific set of conditions, power level/voltage etc where it does hit each spec

[snaptwo]

Originally Posted by john61ct

Not saying they are angels, but Genasun does have a rep for making top-heavy stuff.

There is likely a very specific set of conditions, power level/voltage etc where it does hit each spec

Yup, that would be true. :-) I wish they would write better and more honest marketing literature though.

[john61ct]

That's a tough ask, marketing Dept has more clout than the engineers. And being the most up-front with all details would probably cost market share.

The acid test for me is, can you reach the latter group and get honest details?

Caveat emptor, that's our job.

[snaptwo]

I’d agree. Question - why go this route rather than use 48DDC nominal solar panels? It seems the long way around. Are your cells embedded in the boat?

[foggysail]

Originally Posted by snaptwo

I’d agree. Question - why go this route rather than use 48DDC nominal solar panels? It seems the long way around. Are your cells embedded in the boat?

The OP is aware that he can wire his panels in series but seeks an exotic, difficult solution instead

[OceanPlanet]

Originally Posted by snaptwo

I’d agree. Question - why go this route rather than use 48DDC nominal solar panels? It seems the long way around. Are your cells embedded in the boat?

Because on many boats it is difficult to fit on the larger array without shading issues. With four 12V nominal panels in series if one is shaded that would stop the 48V charging. Whereas if each panel has it's own voltage-boosting controller then even if one panel has sun there is still charging.

However, if no shading then the 4S config with a Buck MPPT would be less $.

[snaptwo]

Yes indeedie I agree - series panels are problematic. I take it you are taking about really small panels then. Ok, one final question, what do you have that required 48VDC service? Most (almost all) commercial vessels are 24VDC. I have seen some 48VDC around, but it is so close to the 50VDC LVDC cutoff that a charge voltage exceeds 50VDC, and you are into a whole new electrical code (and cost).

[Ironman162]

Just upgraded to 500w solar with a 400 wind turbine charging 500Ah AGM battery bank through a PWM controller.

Works well but can do with more batteries!

Has anyone tried the Tesla battery?