True Power vs Apparent Power

Question

I’m reading through my Solar Inverter/Charge controller manual and I see the Peak Power Rating is 10,000VA. I didn’t recognize the unit “VA”, but it seemed suspiciously close to 10,000 (V)olt (A)mps but I already know Watts=volts x Amps so why wouldn’t the manual just say Watts if that’s what they meant?

So I googled what unit is VA and learned it is indeed an Volt-Ampere. So how does this differ from watts? Further googling showed me that it’s the difference between Real Power and Apparent Power. So what’s that?

After trying to watch several YouTube videos, I just don’t get it. They’re far too technical for me and they all seem to go into circuit design which; I already have a tenuous grasp on electricity as it is.

Please what the difference is!

In: 2

Answer 1

I don’t think I ever used the term apparent power, but see [my previous comment here](https://www.reddit.com/r/explainlikeimfive/comments/wtjb98/comment/il4h6jt/?utm_source=share&utm_medium=web2x&context=3) for a discussion of why Volts and Amps don’t always line up.

The key point for you is that the apparent power is how hard the inverter has to work, and is directly related to how much current is rushing in and out and so heating up all the components inside (which is why this is how the rating is stated). In contrast real power is how much useful stuff you see at the output, which will necessarily be less.

Edit: think of it like this. There is a steady stream of power coming in from the input. There is a steady stream of (real) power flowing from the output of the inverter to the load. But there is also some amount of (reactive) power sloshing backwards and forwards between the inverter and the load. This doesn’t have any net flow so it doesn’t do useful work, nor does it place any demand on the input. However the total amount of power moving about in the inverter is the sum* of the steady flow and the sloshing (this sum is called the apparent power), and it is this sum which leads to heating which is what limits the capability of the inverter.

*The real and reactive power are actually out of phase so the apparent power is the hypotenuse of a triangle rather than a simple sum.