Parallel Vs. Series PV Panels

[wunmi007]

In a battery bank of 4 (12v 200ah) connected in parallel will result in 12v 800AH and connected in series will be 48Vdc 200AH.
What will be the resulting configuration of 4(12vdc 240w 8a) PV panels connected in a Parallel or Series circuit?

[Sunking]

Still 960 watts. The question is what is the voltage and current when configured in either series or parallel.

First the panels are not 12 volts as it is not possible, they are Grid Tied panels. But all we need to know is two parameters to find all the rest. Simple Ohm's Law states Voltage = Watts / Current. So if your panels are 240 watts with 8 amps them know the voltage has to be 240 watts / 8 amps = 30 volts

So if we parallel all four panels we have 30 volts @ 32 amps. 960 watts = 30 volts x 32 amps.
If all in parallel then we have 120 volts @ 8 amps. 960 watts = 120 volts x 30 amps.

[inetdog]

In a battery bank of 4 (12v 200ah) connected in parallel will result in 12v 800AH and connected in series will be 48Vdc 200AH.
What will be the resulting configuration of 4(12vdc 240w 8a) PV panels connected in a Parallel or Series circuit?

Follow the same model you used for the batteries.
4 in series will be 48V (nominal), 8A, total of 960w.
4 in parallel will be 12V (nominal), 32A, total of 960w.

Note carefully that the panel description is not consistent at all:
A 12V nominal panel, for use with a PWM CC and a 12V (nominal) battery will have a Vmp of about 18V.
But for your panel, a power of 240W and a current (Vmp?) of 8A corresponds to a Vmp of 30V, which is totally not a 12V battery panel and would be wasted if connected to a PWM CC for 12V batteries. Yet it is too low a Vmp to be optimal for a 24V battery bank.

[wunmi007]

Follow the same model you used for the batteries.
4 in series will be 48V (nominal), 8A, total of 960w.
4 in parallel will be 12V (nominal), 32A, total of 960w.

Note carefully that the panel description is not consistent at all:
A 12V nominal panel, for use with a PWM CC and a 12V (nominal) battery will have a Vmp of about 18V.
But for your panel, a power of 240W and a current (Vmp?) of 8A corresponds to a Vmp of 30V, which is totally not a 12V battery panel and would be wasted if connected to a PWM CC for 12V batteries. Yet it is too low a Vmp to be optimal for a 24V battery bank.

I'm confused, if Voltage is constant in Parallel connection and variable in series connection why do you have 48V in the parallel config. or is this a typo?

[inetdog]

I'm confused, if Voltage is constant in Parallel connection and variable in series connection why do you have 48V in the parallel config. or is this a typo?

That was definitely a typo, and I have already fixed it, so it never happened, do you hear me?

[wunmi007]

That was definitely a typo, and I have already fixed it, so it never happened, do you hear me?

[mapmaker]

Simple Ohm's Law states Voltage = Watts / Current.

I learn something new every day... I always thought Ohm's law had something to do with resistance, voltage, and current.

--mapmaker

[Sunking]

I learn something new every day... I always thought Ohm's law had something to do with resistance, voltage, and current.

--mapmaker

You left one out, Watts aka Power

Watts = Voltage x Current
Watts = Current x Current x Resistance
Watts = [Voltage x Voltage] / Resistance

[inetdog]

I learn something new every day... I always thought Ohm's law had something to do with resistance, voltage, and current.

--mapmaker

The power law, in all of its forms as shown in the lovely circle diagram, relates all of the basic electrical quantities. It is more complete than what is commonly thought of as Ohm's Law, but encompasses that too.
Actually I belong to the camp that considers E=IR as the definition of resistance and Ohm's Law as the statement that the resistance, R is a more or less predictable and relatively constant property of the structure through which the current is flowing.

[Sunking]

The power law, in all of its forms as shown in the lovely circle diagram, relates all of the basic electrical quantities. It is more complete than what is commonly thought of as Ohm's Law, but encompasses that too.
Actually I belong to the camp that considers E=IR as the definition of resistance and Ohm's Law as the statement that the resistance, R is a more or less predictable and relatively constant property of the structure through which the current is flowing.

OK name some things that have fixed passive resistance that you use in every day life. Not many thing you can call out except incandescent light bulbs and strip heaters. Those are two things you should avoid using anyway. Most gizmos have dynamic power usage which changes every second. Higher wattage gizmos like Air Conditioning and Refrigeration use constant power that cycles on/off. But something like a desktop computer is very dynamic and at best all you can do is determine how much energy it will use in a day, but from minute to minute is impossible to determine.

[inetdog]

OK name some things that have fixed passive resistance that you use in every day life. Not many thing you can call out except incandescent light bulbs and strip heaters. Those are two things you should avoid using anyway. Most gizmos have dynamic power usage which changes every second. Higher wattage gizmos like Air Conditioning and Refrigeration use constant power that cycles on/off. But something like a desktop computer is very dynamic and at best all you can do is determine how much energy it will use in a day, but from minute to minute is impossible to determine.

Which is why the power laws are so very helpful, but Ohm's Law by itself does not do you much if any good.
And I would not consider a light bulb an ohmic resistor because of its high temperature range. The temperature coefficient of resistance is high, but not orders of magnitude beyond the TC of copper, but the temperature range the light bulb filament operates over is very large, allowing the resistance to change by large multipliers.

[ILFE]

I need some popcorn and a coke, for this thread.

[mapmaker]

OK name some things that have fixed passive resistance that you use in every day life. Not many thing you can call out except incandescent light bulbs and strip heaters. Those are two things you should avoid using anyway. Most gizmos have dynamic power usage

OK, I think you are justifying your 'expansion' of Ohm's law on this basis: The traditional I=E/R does not apply to most loads.

If you feel that way, then realize most loads are inductive or reactive... so your 'expansion' of Ohm's law needs to account for that also.

Of course if you do that (in a readable sized text), your circle will need to be four feet in diameter and that assumes you can do it in a circle... where do the imaginary numbers go on a circle?

--mapmaker

[SunEagle]

OK, I think you are justifying your 'expansion' of Ohm's law on this basis: The traditional I=E/R does not apply to most loads.

If you feel that way, then realize most loads are inductive or reactive... so your 'expansion' of Ohm's law needs to account for that also.

Of course if you do that (in a readable sized text), your circle will need to be four feet in diameter and that assumes you can do it in a circle... where do the imaginary numbers go on a circle?

--mapmaker

Don't forget about Power Factor "PF" and how Harmonics influence Watts and VA in your circle diagram.

[Sunking]

OK, I think you are justifying your 'expansion' of Ohm's law on this basis:

Ohm' Law only works on passive DC circuits. In AC circuit Z replaces R, and Theta enters in the equations.