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Old 29-03-2018, 16:50   #46
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Re: Instant benefit from replacing Solar PWM with MPPT controller?

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Originally Posted by svlamorocha View Post
Both meanings are the same.. Or do we need a separate thread about math?
No need, we went through the same thing with the same person in the Amps v Amp hours v Amp per hour thread at great length. Apparently it's just incomprehensible to certain people.
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Old 29-03-2018, 17:04   #47
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Re: Instant benefit from replacing Solar PWM with MPPT controller?

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No need, we went through the same thing with the same person in the Amps v Amp hours v Amp per hour thread at great length. Apparently it's just incomprehensible to certain people.
Or maybe, just maybe, I just like to argue.....

Or is this abuse. Might be in the wrong room.
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Old 29-03-2018, 17:21   #48
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Re: Instant benefit from replacing Solar PWM with MPPT controller?

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The difference is only significant if talking about alternating current.

Watts is "real power" , VA is "apparent power".

The real "difference" is the "reactive power" in the circuit.

But it's probably simpler to consider "power factor" for equipment using alternating current. The power factor is the ratio between the two.

Power factor = W/VA

Real power (W) is the power that performs work or generated heat. It is the integral of instantaneous voltage multipled by instantaneous current measured over time, divided by that time. It is NOT easy to measure for alternating currents!

Apparent power (VA) is the RMS voltage multipled by the RMS current. it is useful for calculating wire/fuse sizes etc.

In DC circuits, they are essentially the same.

The important thing is that you need to size circuitry for VA, not W.
I think you may be confusing Root Mean Square equivalents with VA. They aren't the same. RMS is simply the DC equivalent voltage and current of a sinusoidal AC supply. Power factor, on the other hand, represents the lead or lag between current and voltage in an AC load.

AC power supplies like gensets or inverters are most likely to have a VA rating specified, as this expresses maximum rating of the power source without considering the power factor of any circuit it is connected to.
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Old 29-03-2018, 18:20   #49
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Re: Instant benefit from replacing Solar PWM with MPPT controller?

No confusion on my part.

It would be more accurate to say that "root mean square" (RMS) is the mathematical method of determining the DC equivalent Voltage or Current.

VA is Vrms x Arms

And that is not only true of sinusoidal waves it is applicable for any alternating wave form.

Whether a power factor of less than 1 is the result of capacitive or inductive loads (lead/lag) is irrelevant to the different between Watts and VA.

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Old 29-03-2018, 18:21   #50
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Re: Instant benefit from replacing Solar PWM with MPPT controller?

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I had a teacher just like you, I proved him wrong more than once and he lost all credibility. I have an Electronics engineering degree, a PhD in computer science, run two companies and he is still a teacher. He also told me that women shouldn't do science, we don't have the brains for it.
You remind me of him a lot. Youre real name isn't Richard Edwards is it?
Why not prove StuM wrong about kVA then, (or admit he's right) rather than resorting to childish name calling?

At present, it's not his credibility that is suffering.
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Old 29-03-2018, 18:25   #51
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Re: Instant benefit from replacing Solar PWM with MPPT controller?

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No need, we went through the same thing with the same person in the Amps v Amp hours v Amp per hour thread at great length. Apparently it's just incomprehensible to certain people.
Maybe instead of Watt hours, we should talk in Joules? That ought simplify things, right?
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Old 29-03-2018, 19:06   #52
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Re: Instant benefit from replacing Solar PWM with MPPT controller?

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Maybe instead of Watt hours, we should talk in Joules? That ought simplify things, right?
If you can handle bigger numbers, that may help - but kiloJoules would keep the numbers more manageable.
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Old 29-03-2018, 19:16   #53
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Re: Instant benefit from replacing Solar PWM with MPPT controller?

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Charging LiFePo4, which can take all the current you can throw at them. The optimum case to demonstrate the supeiority of MPPT.

Where you are using solar during the day for charging FLA and to power variable house loads, you will very rarely see anything like that improvement.
Only if your main use of PV electricity is charging your bank.

Many people have useful work for the "excess" once a lead bank's acceptance drops.
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Old 29-03-2018, 19:22   #54
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Re: Instant benefit from replacing Solar PWM with MPPT controller?

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No confusion on my part.

It would be more accurate to say that "root mean square" (RMS) is the mathematical method of determining the DC equivalent Voltage or Current.

VA is Vrms x Arms

And that is not only true of sinusoidal waves it is applicable for any alternating wave form.

Whether a power factor of less than 1 is the result of capacitive or inductive loads (lead/lag) is irrelevant to the different between Watts and VA.

What can I say? If you think RMS and power factor is the same thing then you're confused. Think phase shift.
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Old 29-03-2018, 20:59   #55
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Re: Instant benefit from replacing Solar PWM with MPPT controller?

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What can I say? If you think RMS and power factor is the same thing then you're confused. Think phase shift.
Who said that?

Power factor is the ratio of Watts to VA where Watts is "real power" and VA is "apparent power" (the vector sum of "real power" and "reactive power").

VA is Vrms x Arms for alternating current systems.

Added: Since you've introduced phase shift - that is the fundamental cause of reactive power.
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Old 29-03-2018, 21:22   #56
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Re: Instant benefit from replacing Solar PWM with MPPT controller?

While you guys argue your watt hour semantics I will point out that if you are using your mppt controller for solar panels wired in series you might see a bigger gain. But if your panels have shading issues you will need to wire the panels in parallel anyway. I have two 195 watt panels fixed mounted at different angles to each other and one big mppt controller. I would be better off with two smaller controllers.
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Old 29-03-2018, 21:26   #57
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Re: Instant benefit from replacing Solar PWM with MPPT controller?

I am overwhelmed by the talent that my simple enquiry has unleashed.

So, I know I just need another panel......my next dilemma - what colour? (Primary shades only!)
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Old 29-03-2018, 22:54   #58
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Re: Instant benefit from replacing Solar PWM with MPPT controller?

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Originally Posted by Suijin View Post
The there are 24”x60” panels that are 160 watt so I’d start with replacing your panels.
I just bought a pair of panels, 5 feet by 2 foot 3 inches that are 250 Watts each,
59 inches by almost 27 inches.
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Old 29-03-2018, 23:02   #59
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Re: Instant benefit from replacing Solar PWM with MPPT controller?

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Originally Posted by StuM View Post
Who said that?

Power factor is the ratio of Watts to VA where Watts is "real power" and VA is "apparent power" (the vector sum of "real power" and "reactive power").

VA is Vrms x Arms for alternating current systems.

Added: Since you've introduced phase shift - that is the fundamental cause of reactive power.

Your answers sound like google copy and paste, even down to the font change. I'm not convinced you really do understand the practical difference of VA and Watts.
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Old 29-03-2018, 23:16   #60
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Re: Instant benefit from replacing Solar PWM with MPPT controller?

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Originally Posted by john61ct View Post
Watts per hour is commonly used to define watt-hours, but I agree is actually confusing, since watt-hours per unit of time is more precisely correct.

However using such nitpicking to put others down is indeed uncalled for.
How many Whats? / hour do you get here if you ask a question?
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