MPPT Controler question

[Ri_not]

Hi all,
I am finishing up a small off grid system, I will have (four) 200 MW solar panels which will give me 800MW at 12 vdc.This will feed a Powmr 60A MPPT controler. This will be feeding ( six ) 12 volt 100ah batteries that will be wired in series and parallel, to give a 24 battery bank. The 24 VDC from the batteries will feed my 3200 watt inverter. Just want to throw it out there for advice.

Thanks

 

[TomC4306]

So, what is your question?

 

[rmaddy]

What is a "MW" solar panel? Certainly you don't mean megawatt.

800W of solar on a 24V system means you only need a 30A MPPT SCC. So you have capacity to double your solar to 1600W if the need arises.

Other than that I have no idea what advice you're looking for.

 

[Ri_not]

My Bad have 4 200 miliwatt solar panels in P to give me 800 Milliwatts

 

[cs1234]

Hi all,
I am finishing up a small off grid system, I will have (four) 200 MW solar panels which will give me 800MW at 12 vdc.This will feed a Powmr 60A MPPT controler. This will be feeding ( six ) 12 volt 100ah batteries that will be wired in series and parallel, to give a 24 battery bank. The 24 VDC from the batteries will feed my 3200 watt inverter. Just want to throw it out there for advice.

Thanks

So you will have 800 watts of solar (peak) going into a 24v/300ah battery hooked up to a 3200 watt inverter? 3200 watt inverter / 24v is 133 amps. Sounds like you should be fine on all fronts. People here would suggest you use 4/0 cable for each device to keep your cables cool.

 

[rmaddy]

That can't be right either. 800mW is 0.8W. That would be a solar panel smaller than a postage stamp.

You must mean 4 200W (watt) solar panels.

 

[rmaddy]

People here would suggest you use 4/0 cable for each device to keep your cables cool.

4/0AWG is way bigger than needed for 123A (really 140A for a 3200W inverter on a 24V system). 1AWG or 1/0AWG is plenty big enough. Sure 2/0AWG or 4/0AWG will work and stay plenty cool but 1/0AWG isn't going to get too warm.

4 200 miliwatt solar panels in P

Does P mean parallel? Why all 4 in parallel? 2S2P or maybe 4S (if supported) would likely be better.

 

[Ri_not]

So you will have 800 watts of solar (peak) going into a 24v/300ah battery hooked up to a 3200 watt inverter? 3200 watt inverter / 24v is 133 amps. Sounds like you should be fine on all fronts. People here would suggest you use 4/0 cable for each device to keep your cables cool.

If im useing 800watts at 12 volts will this charge the 24 vdc battery pack ok or should i put 2 solar panels each in series than parrellel to give me 24 volts from the solar panels to the solar controller

 

[cs1234]

If im useing 800watts at 12 volts will this charge the 24 vdc battery pack ok or should i put 2 solar panels each in series than parrellel to give me 24 volts from the solar panels to the solar controller

Most MPPT charge controllers are going to need more voltage coming in from the panels than the voltage they are sending out to the battery. If you are trying to charge a 24v battery you are going to need more than 24 volts coming from the solar panels to the charge controller.

Without the specs of your panels and charge controller we can't really say for sure how you should wire them up. Are your solar panels all at the same angle at the same spot so they will all get the same amount of sun at the same time? Or is each panel in a different spot, at a different angle?

Assuming the regular output of a generic 200watt solar panel, I'm guessing you should be fine putting them 2s2p (2 per string, 2 parallel strings) to your charge controller and still be at a high enough voltage to charge a 24v battery pack. You might even be lucky and have a low enough string voltage that you don't kill yourself if you make a mistake if you stay at 2s2p. ?

 

[cs1234]

4/0AWG is way bigger than needed for 123A (really 140A for a 3200W inverter on a 24V system). 1AWG or 1/0AWG is plenty big enough. Sure 2/0AWG or 4/0AWG will work and stay plenty cool but 1/0AWG isn't going to get too warm.


Does P mean parallel? Why all 4 in parallel? 2S2P or maybe 4S (if supported) would likely be better.

Do you want them to have a string with potentially 80+ volts on it? I think for their own sake at this point, they should keep their string under 50 volts for safety.

 

[rmaddy]

Do you want them to have a string with potentially 80+ volts on it? I think for their own sake at this point, they should keep their string under 50 volts for safety.

My 3 panels in series have a Voc of about 120V. Plenty of people have 100V and 150V SCCs. Look at all the people getting all-in-ones with 450V max PV input voltages. Take proper precautions and it can be done safely, just like anything else.

Nothing wrong with giving a warning about dealing with 50+ or 80+ volts but believe me, even the 24V LiFePO₄ batteries will knock your socks off. I took a chunk out of a battery wire lug once because a switch I thought was off wasn't. A 12V car battery can kill you under the right (wrong) conditions.

 

[Ri_not]

So would it be safe to say if I take 4 solar panels at 200W at 12VDC make two strings of 2 each in series for 24 VDC and then take those 2 strings and place them in parrellel , feeding them into a 60amp solar mppt controler will charge my battery bank cofigured for 24 volts. God every time I think I get were I need to be. UGGGHHH

 

[rmaddy]

You need to post the actual specs of your panels. They are not really 12V panels. That's just a marketing term that has no meaning when using an MPPT SCC.

Post your specs and we can give you a clear answer.

 

[Ri_not]

195 watt 18 volts +-3 %

 

[Ri_not]

Thanks for all your assistance much appricieated

 

[rmaddy]

We need to see the full specs. It needs to show Voc, Vmp, Isc, and Imp. Post a link to the panels.

Also post a link to the solar charge controller you have.

 

[cs1234]

My 3 panels in series have a Voc of about 120V. Plenty of people have 100V and 150V SCCs. Look at all the people getting all-in-ones with 450V max PV input voltages. Take proper precautions and it can be done safely, just like anything else.

Nothing wrong with giving a warning about dealing with 50+ or 80+ volts but believe me, even the 24V LiFePO₄ batteries will knock your socks off. I took a chunk out of a battery wire lug once because a switch I thought was off wasn't. A 12V car battery can kill you under the right (wrong) conditions.

I figured in this case it deserved a mention because it seemed they aren't clear on some of the basics.

 

[Ri_not]

here is the link to the panel : https://www.eco-worthy.com/products/195w-12v-monocrystalline-solar-panel
Here is the link to my controler :https://powmr.com/solar-charge-cont...to-solar-regulator-with-lcd-display-mppt-60a/

 

[cs1234]

here is the link to the panel : https://www.eco-worthy.com/products/195w-12v-monocrystalline-solar-panel
Here is the link to my controler :https://powmr.com/solar-charge-cont...to-solar-regulator-with-lcd-display-mppt-60a/

Panels :

Rated Power: 195W
Open Circuit Voltage (Voc): 21.6V
Short Circuit Current (Isc): 10.83A
Working Current (Iop): 9.02A
Output Tolerance: ±3%
Temperature Range: -40℃ to +80℃

Charge controller :
12V system: DC20V~DC80V
24V system: DC37V~DC105V
36V system: DC50V~DC160V
48V system: DC72V~DC160V

The maximum PV input voltage (Voc): DC190V
Maximum wattage:
12V system (720W) ;
24V system (1440W) ;
36V system (2100W);
48V system (2800W) 60 amp mppt charge controller ;

Ok, now we have some numbers to work with. The strange thing I'm seeing is that the charge controller claims different maximums for the solar voltage input depending on charger output voltage.

Honestly, I would say just do your batteries at 36volts, 3s2p and wire up all 6 of your solar panels onto one string, 6s. I'm assuming all 6 panels will be at the same angle and direction, and not scattered about in different spots.

This also assumes you aren't living someplace that gets really cold though, you don't want to exceed the the 160v/190v rating of your charger when the voltage increases as the weather gets cold. You'll probably be pretty safe at 6 panels at roughly 130v though, that gives you a bunch of leeway even using the weird 160v number it states instead of the maximum 190v it lists elsewhere.

 

[Ri_not]

Thanks for the input, unfortunatly I live in the northeast that does get cold,
I do have one question you said keep the four panels on one string in parrallel at there rated voltage 21.6 voc to the controller?
I will need to keep battery bank at 24VDC, that is what my inverter rated input is. It is none switchable.
Thank you,