Poor Design? How can I hook up Mixed Panels?

[jo_sail]

Originally Posted by Spot

The Amazon vendor I last bought from sells them both ways at 30 amps.

Is there a way to determine if a controller is really one or the other?

Is it still good practice to fuse the charge controller output to battery?

I‘m very sure that the right dark blue controller is PWM only. The menue has two set points only and I opened it. The corcuit looks extremely simple, although you never know, what is in the IC.

I even think,this PWM is not able to handle 30 A continuously. The MOSFETs are without printed part number on them. Still they might easily be good for 30 A. But the conductive paths are so thin, that I chose to put extra solder on them, in order to allow for enough current to start an electrical motor, and thereby reduce the risk of overheating the the conductive path.

This PWM controller came from the „bay“ at added cost of 2 € together with a small solar panel. You can not expect a solid MPPT for that money.

[Statistical]

Originally Posted by Spot

The Amazon vendor I last bought from sells them both ways at 30 amps.
Is there a way to determine if a controller is really one or the other?
Is it still good practice to fuse the charge controller output to battery?

It looks like you bought the one on the left. While they are "made" by the same company and are similar there are enough differences it is entirely possible the one you got actually is MPPT. The one of the right though is almost certainly a PWM and that is what the OP said was his "MPPT" charger.


The easiest way to check if you have a real MPPT charger would be don't buy garbage I kid. No the easiest way to check would be to measure the volts and amps on the input side and compare it to the output side. PWM will chop off any excess volts beyond the charging voltage meaning if input voltage is significantly higher you will get significantly lower total power output because the volts are chopped down and amps are constant.


As an example:
Your panel is outputting 10A @ 20V. Battery charging voltage is 13.5V.

A PWM controller simply outputs 10A @ 13.5V. Note this is about 30% less power because amps stay the same and volts get chopped down the voltage needed by the battery. How efficient it is depends on the difference between panel string voltage and the battery charging voltage ideally as low as possible.

The same example panel on a MPPT charger should show >10A amps output (as long as battery SoC% is low enough to take it all). You might see something like 14.1A @ 13.5V (10A * 20V = 200W input. 200W *0.95 = 190W output. 190W/13.5V = 14.1A). It converts the input power to roughly the same output power usually 95%+ efficiency although maybe less on cheap models and as a result produces more amps.

[Kelkara]

I'm pretty certain those dark blue controllers are all pwm, although I've seen some sellers claiming that they are mppt.

If your 15W panel really is only 13V then with a battery voltage of 13.4V that explains why the controller fails to deliver any charge.

for the other panels, to check if the controllers are regarding 13.4v as full batteries, so not delivering charge ... try increasing the dc consumption (turn on lights, pumps etc) to at least as many amps as you're hoping the panels to supply and see if the solar current increases.

[Senojev]

Ditch the 15w panel … it is if no use to you. Buy two quality MPPTs, one for each panel, wire to battery bank with fuse or breaker close to MPPT. Ditch the rest of the circuitry.

[Senojev]

Ditch the 15w panel, it is doing you no good at all. Buy two quality MPPTs for the two remaining panels and wire them directly to the battery bank with fuses of the appropriate size. Ditch the remaining circuitry.

If you batteries are over 13v you are at float and solar should be giving a minimal charge.

[wholybee]

I agree, ditch the 15W panel. It doesn't produce enough voltage to effectively charge your batteries. In parallel with the other panels, it literally will do nothing.

100W and 200W are too different to work effectively in the same circuit. I would start by just removing the 15W panel, removing the solar relay thing that doesn't need to be there, and then test how it works. If you are happy, great. If not, replace the remaining MPPT controllers.

[skenn_ie]

1) In low power panels, I have only seen ones intended for direct connection to batteries. The 13V spec says that this is one of them.
2) I am fairly sure that your controllers are PWM ones rather than Buck controllers. This is easily confirmed by looking inside them. Buck controllers use an power inductor in the conversion circuit. PWM ones don't. PWM won't work well in parallel.

[tbodine88]

Originally Posted by Spot

Hi Tom, what are the two unlabeled items near the ACR and the two colored ones upper right corner of schematic?

If you reduce the system to one solar panel, one controller, one battery-do you get decent readings at the controller and battery?

the two unlabeled items are the batteries.


the two colored items in upper right corner are digital battery monitors, I wanted a separate monitor for each battery.

[tbodine88]

Originally Posted by skenn_ie

1) In low power panels, I have only seen ones intended for direct connection to batteries. The 13V spec says that this is one of them.
2) I am fairly sure that your controllers are PWM ones rather than Buck controllers. This is easily confirmed by looking inside them. Buck controllers use an power inductor in the conversion circuit. PWM ones don't. PWM won't work well in parallel.

Thanks. These are small, I suspect mppt. If I can pry one open I will. I am away from the boat at the moment so it will be a while.


During the week long trial, I think the max current was .5 A


After a day of sailing with very little load besides the depth meter the batteries were nearly fully charged.


I think I'll need to make a Arch over the cockpit to provide a better traveler and more room for solar.


Thanks

[tbodine88]

Note that after running this system for a couple of days it became obvious it would not deliver the current I was seeking. So now I am contemplating other designs.

Thanks for your advice as and help.