BP mst-43 charge controller

[Northern Sun]

I am looking to find a charge controller for this BP panel I was given.

It is a MST-43 the info on it is as follows.

Pmax 43.0W

Voltage at Pmax 71V

Current at Pmax 0.616A

Open circuit voltage (Voc) 101V

Short Circuit Current (Isc) 0.787A

Guraranteed minimum Pmax 38.7W

 I just have the one panel and will be inverting to 110 from 12 volt batterys.

I would like to find a small charge controller that will handel this one panel.

Any ideas will be welcome

Thanks

Mike

[coldspot]

mike-

"a small charge controller that will handel this one panel"

If it was me

I'd go ahead and buy something of size and quality

this would be of better use down the road and be very able to handle the 40ish Watt panel you have.

C35

C40

C60

DO some researching here in the solar section

Using the google search works better but just reading a lot would be of great help to you and an easy way to save money, (Research)!

$0.02

[Northern Sun]

Thanks

I have been looking and doing a lot of reading. The part that has me confused is the 101 volts.

I have a small controller but it states 30 volts ( voc) max.

I don't think I will ever get another mst-43 panel so I would hate to invest a lot into a controller to service just this one panel.

I have not found any controllers that state they will handel 101 volts.

Also the instructions on the mst-43 also clame that when first deployed you can expect to see 12% higher voltage for a time.

WoW a solar panel I can weld with.LOL

Again Thanks.

Mike

[ghurd]

You may have some problems with that one.  It seems to be for 48V use.

Most standard 12V controllers won't take the voltage.

It may not need a controller for 12V use. The output, or current into a battery, will be less than 0.75 amps.  About 9 watts.  A 6 amp diode will probably work just fine.

G-

[Flux]

To get any real use out of that panel on 12v you would need a MPPT controller, but unless you intended to upgrade with similar ones, it would be an expensive way to achieve very little.

As Ghurd said, it will produce about 700mA directly into 12v. Any 12v controller would do the job( if you needed it) as long as you work in diversion mode. The battery would hold volts down. Don't try it in series mode with that high voltage panel.

Flux

[Northern Sun]

Hay Guys Thanks

Math is really NOT my strong point. I am in the process of building my first panel using some cells I got off eBay. Figuring the layout is about to burn up that last glowing brain cell i own.

I have the air-x wind generator in 24 volt and also bought one of those 24v to 220 phase able Inverters.

I had planed to set this all up until my wife saw the tower. That project went on hold.

For now I need to be content with solar. (For sale air-x and inverter looked at very little)

Thanks again I will try the blocking diode and see if I make smoke.

Mike

[Nando]

The controller needs to have a handling voltage of at least 120 volts.

I am not aware of one converting to 12 volts, the conversion ratio of Vmax = Vmppt of 71 volts to 12 volts is 5.9:1.

The efficiency may suffer with any of the common types, like a BUCK converter, though the efficiency may be around 85 to 90 %.

The C35, or C40 family does not work here, the reason is simple, these types are not RATIO converters but "pulsers" at low frequency to connect the power source DIRECTLY to the load (battery) limiting the current by opening the MosFet at around 100 to 200 Hertz.

A fly back, a single MosFet forward, or a two Mosfet forward converter may do, though the efficiency may run in the 80 to 85 %.

Nando

[ghurd]

Quick thought.

You may be able to use it for charging 48V in a small UPS.

It would make ~35W into the batteries, and the inverter is built in.

It would be past most people, but it could be done. With enough time and effort.

Honestly, I'm not sure they make a small 48V UPS.

G-

[craig110]

Using a high voltage panel is, as you've found out, not the easiest or most cost-effective way of charging 12v batteries.  Have you considered swapping panels?  If someone can make good use of a high voltage panel and has a ~30-40 watt 12v (nominal) panel laying around, you both would come out ahead by swapping panels.  If you were lucky enough and the other person was in your area, you might not even have shipping costs to worry about.

Craig

[nothing to lose]

"Honestly, I'm not sure they make a small 48V UPS."

I don't know either. Even that big rack mount 2200 we picked up in Eastlake is only 24V and all those smaller ones are 24V also. The only 48V I have found so far are the Matrix 5000 units I have, but that's not to say they are are not out there but they must be rare if they are.

 I had a couple older units with 4 batteries and thought I might get lucky. Nope, wired as series and parralel for 24V like the 2200 is.

I just put an old motor coversion back up today that is great for 48V so I was digging around looking for a 48V UPS also, never found one though. I don't want to use the Matrix for this, it's too big to be moving around. A nice small UPS about 1000watts and sinewave is what I was looking for and those are all 24v so I am trying one on the genny, it works but bogs down a bit much. 12V is like shorting it out.