24v 2000watt system

[brewmium]

Hi all!


I've gotten the components for William's 24v system. I'm trying to get a "real world" max of what i can add, solar panel wise.

I'm trying to figure out how many solar panels I can hook up to the system, given the panels i've chosen to go with.

I have the "EPEVER MPPT Solar Charge Controller 40A 150V PV Solar Panel Controller" recommended. The specs say:

• Max PV Open Circuit Voltage: 150V / 138V
• Max PV Input Power: 520W (12v battery) / 1040W (24v battery)

I choose this panel, and have 2 of them: BougeRV 170 Watts Solar Panel, 12 Volts Monocrystalline Solar Cell
Their specs are

• Max. power voltage(Vmp): 19.01V
• Max. power current(Imp): 8.91A
• Open circuit voltage(Voc): 22.5V
• Short circuit current(Isc): 9.44A
• Series fuse rating: 15A
• Max. system voltage: 1000V
• J-Box IP Rating: IP65

So... If I do my math correctly, I could hook up 2 in series, and 6 of those pairs in parallel to "max out" that controller? giving me 1020w @ 24v?

Or, does the the current from the 12 panels make me hit a different limit, like the 40A waiting of the charge controller?

Sorry for such a basic question, but i am trying to understand the terminology.

much thanks,
-eric

 

[kernel]

Hi all!


I've gotten the components for William's 24v system. I'm trying to get a "real world" max of what i can add, solar panel wise.

I'm trying to figure out how many solar panels I can hook up to the system, given the panels i've chosen to go with.

I have the "EPEVER MPPT Solar Charge Controller 40A 150V PV Solar Panel Controller" recommended. The specs say:

• Max PV Open Circuit Voltage: 150V / 138V
• Max PV Input Power: 520W (12v battery) / 1040W (24v battery)

I choose this panel, and have 2 of them: BougeRV 170 Watts Solar Panel, 12 Volts Monocrystalline Solar Cell
Their specs are

• Max. power voltage(Vmp): 19.01V
• Max. power current(Imp): 8.91A
• Open circuit voltage(Voc): 22.5V
• Short circuit current(Isc): 9.44A
• Series fuse rating: 15A
• Max. system voltage: 1000V
• J-Box IP Rating: IP65

So... If I do my math correctly, I could hook up 2 in series, and 6 of those pairs in parallel to "max out" that controller? giving me 1020w @ 24v?

Or, does the the current from the 12 panels make me hit a different limit, like the 40A waiting of the charge controller?

Sorry for such a basic question, but i am trying to understand the terminology.

much thanks,
-eric

You have it correct. Use the listed rating of a charge control and assume it on the battery or controller output side of the unit. (Edit; unless there is other reference in the manuals)

Some manufacturers will spec the pv input side as there may be a disparity, 15a pv input 25A output for example.

Either way, you are limited by both, but usually (many systems) you will hit max output current before you load the pv input to max.

In my case i am loaded 20% heavy on the pv input on one controller amd have another controller as an auxilliary charging source to assist in long strings of overcast days or wven to beef up output when arrays are covered in snow.

The combined input current then is over the max charge rate of my battery, so it has to be attended. Fortunately if i turn it on, i dont have to worry about it for 24 hours or more usually.

^^ dont do this. I dont suggest operating like this and its easy enough to automate. i do it because i can and its preferred to having a generator in my system or on my property.

 

[brewmium]

You have it correct. Use the listed rating of a charge control and assume it on the battery or controller output side of the unit. (Edit; unless there is other reference in the manuals)

Some manufacturers will spec the pv input side as there may be a disparity, 15a pv input 25A output for example.

Either way, you are limited by both, but usually (many systems) you will hit max output current before you load the pv input to max.

In my case i am loaded 20% heavy on the pv input on one controller amd have another controller as an auxilliary charging source to assist in long strings of overcast days or wven to beef up output when arrays are covered in snow.

The combined input current then is over the max charge rate of my battery, so it has to be attended. Fortunately if i turn it on, i dont have to worry about it for 24 hours or more usually.

^^ dont do this. I dont suggest operating like this and its easy enough to automate. i do it because i can and its preferred to having a generator in my system or on my property.

Thank you @kernel! Given the cost of bracketing, and do-dads perpanel, I’m considering going with higher watt panels... this is on my shop, which is 24x24. i don’t really know how I would mix panels. Or does the MPPT save my bacon on That?

 

[kernel]

Yes, likely overcurrent on the pv input. You could run more modules in series for lower current, bit will still likely hit the suggested watt limit. Even if you do the math. Use the makers specifications amd instructions for everything.

Quick math is generally done for a circuit for rough selection, then you are usually going to need to break the system down hard for limits.

The battery in bulk charge or fastest rate and lowest state of charge, will have higher current requirements than in a finishing state or current taper charge. (Lithium all the way through?) Nominal voltage can be used or absorb or highest charging voltage (lithium?) And it wwill sometimes negatively affect a prior rough selection.

 

[brewmium]

Yes, likely overcurrent on the pv input. You could run more modules in series for lower current, bit will still likely hit the suggested watt limit. Even if you do the math. Use the makers specifications amd instructions for everything.

Quick math is generally done for a circuit for rough selection, then you are usually going to need to break the system down hard for limits.

The battery in bulk charge or fastest rate and lowest state of charge, will have higher current requirements than in a finishing state or current taper charge. (Lithium all the way through?) Nominal voltage can be used or absorb or highest charging voltage (lithium?) And it wwill sometimes negatively affect a prior rough selection.

Thank you! That makes sense. An advice on what I use to combine the pair? At the panels before making the run down to the controller?

 

[kernel]

The mppt allows wider module voltage selection and generally higher pv string voltage ratios to battery voltage. There are efficiency limits, but i will usually have mppt controls for the higher pv voltage down conversion on distant arrays. Power point tracking will convert more pv power in certain conditions, otherwise, you are still just modulating pulse width. Meaning mppt sometimes has little effect on total power production amd sometimes as much as 30 percent higher claimed harvest. Cold grey overcast.... more current at battery voltage.

 

[kernel]

Well, we have had some discussion on this recently!

Depending on your approach you can be anywhere between these scenarios....

You can also use parallel mc4 connectors. 2 strings of 3 or 4 panels perhaps.
If you want shop power, i would source the largest wattage panels you can at the best dollar per watt cost you approve. Dont buy from lowest bidder!

 

[kernel]

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