mppt charge controller - ZLPOWER ??

[Mike90250]

Battery Wattage is correct. Even more correct would be to call it Wattage Delivered to Battery, but it's the same thing really.

MPPT controllers work by watts in = watts out minus 5%.

Your Wattage Delivered to Battery is the same, to the limits of the controller
400W delivered at 12V = 33amps
400W delivered at 24V = 16amps

If you have chosen a battery voltage that hits the amps limit of your contrller, you need to re-design the system to a different voltage, or live with the losses you have chosen

[Sunking]

When you said Battery Wattage .. I think you implied Battery Voltage

Correct my bad, and yes you need a 40 amp controller

[pmaru77]

I'm not going to get into the technical issues at hand here, but wanted to make a comment. Why would someone scrimp on a cc when they have at least 100's of dollars (if not 1000's) invested in panels, and 100's of dollars (if not 1000's) invested in batteries.
So why not spend an extra 50 to 100 bucks on a quality MPPT controller? Unless you are a re-seller.

That being said, I do not have an MPPT controller, because I did not know about their existence.

[Sunking]

I'm not going to get into the technical issues at hand here, but wanted to make a comment. Why would someone scrimp on a cc when they have at least 100's of dollars (if not 1000's) invested in panels, and 100's of dollars (if not 1000's) invested in batteries.
So why not spend an extra 50 to 100 bucks on a quality MPPT controller? Unless you are a re-seller.

That being said, I do not have an MPPT controller, because I did not know about their existence.

It is not so much technical, but rather simple economics. As a rule of thumb below 200 to 300 watts in panels, economics dictate a PWM controller. Above 300 watts you cross the line and now MPPT becomes less expensive because it takes less panel wattage.

[billvon]

So why not spend an extra 50 to 100 bucks on a quality MPPT controller?

Potential reasons:

1) You don't need it (i.e. you don't need the extra power.)
2) You are combining outputs of several disparate panels.
3) You are combining outputs from panels oriented in different directions.
4) You are sensitive to EMI (electromagnetic noise.)
5) You have a diversion load you want to use.

[conntaxman]

solar panel connection

I have a small {lol} question in which way is the best/better way to wire panels. I'll use 4 panels, each 65watt x 3.5 amp x 18vdc. I guess im trying to get more amp's. I now have them all in parallel. Should I take Two and wire them in parallel and then take those and connect them to the other Two in Series. It would them be 36 vdc, ...BUT would it be 3.5 +3.5= 7AMPS, Then going through the Two in series 7 + 3.5 =10.5 amps at 36 vdc.
Tks
John

[pmaru77]

watts=voltage x ampers

watts is fixed

so the lower the voltage, then the higher the amperage. So wire them in series to keep the voltage down....if this is what you really want to do.

EDIT: parallel...not series. + to + to + to + - to - to - to -

[Sunking]

If you really have a MPPT controller you want the amperage to be as low as possible, and the voltage as high as possible. You would want to wire all 4 panels in series which would give you 72 volts @ 3.5 amps.

If you have a PWM controller then you only have one lousy option to wire all 4 of them in parallel assuming you are operating a 12 volt battery which gives you 18 volts @ 14 amps.

[Sunking]

So wire them in series to keep the voltage down....if this is what you really want to do.

Incorrect answer. Wire them in series and the voltage adds. Wire them in parallel current adds.

[pmaru77]

Incorrect answer. Wire them in series and the voltage adds. Wire them in parallel current adds.

Did I screw up again? series parallel series parallel.......I better stick to +'s and -'s. I always get it backwards except when actually wiring.

[Sunking]

Did I screw up again?

Yeah you did.

Series Circuits Vt = V1 + V2 + V3... I1 = I2 = I3...
Parallel Circuits It = I1 + I2 + I3... V1 = V2 = V3....

So with the example given of 4 panels with 18 volts @ 3.5 amps:

Series = 18 + 18 + 18 + 18 = 4 x 18 = 72 volts @ 3.5 amps = 252 watts
Parallel = 3.5 + 3.5 + 3.5 + 3.5 = 4 x 3.5 = 14 amps @ 18 volts = 252 watts

[conntaxman]

Solar cell panel

ok. so I'll wire the in series up to the voltage of the grid tie inverter.
tks
John

[pmaru77]

ok. so I'll wire the in series up to the voltage of the grid tie inverter.
tks
John

I thought you wanted max amps? then parallel
max voltage ...then series.

I think you want max voltage.

[conntaxman]

solar panel connection

I thought you wanted max amps? then parallel
max voltage ...then series.

I think you want max voltage.

-------------------------
Guess i was tring to get both. From four panels now im only drawing 8 amps at about 25 volts.

[Shibby75]

This forum has been very informative to me since im just getting into solar power.

I just want to share my experience with this mppt controller, it came in an unlabaled box.

My system at first setup was 2 x120w parallel conection mono panel, a china 600w inverter and locally produced 100ah flooded battery that is connected with the zlpower sl-40a.

Max charging amp from 2 parallel 120w panel was 11amp. So no big increase even with mppt

When i connected the panels as series, i got 14amp. So i do think this mppt really works.