Help me understand inverter efficiency

[Marion Carter]

DC to AC conversion is costly conversion of energy right? Does efficiency from DC to AC change if you have large or small inverter?

 

[smritte]

"DC to AC conversion is costly conversion of energy right?"
Yes.
" Does efficiency from DC to AC change if you have large or small inverter?"
Not necessarily. If the same amount is pulled through two diffrent sizes, the total loss will be similar as long as their both the same design.

Internal inverter loss is due to its component's and design. You could put two of the same size and type, next to each other and see a difference in loss. Odds are unless one was inferior to the other, the difference is neglectable. Another factor is the bigger ones may have more features. If the features are always on (Bluetooth, lights, display...),their will be more loss than a smaller one.

Most of the loss is because you have to change DC to AC then step it up through a transformer or a multiplier. There's several ways to do this. The "Pure Sine Wave" systems are better, but can have more loss then the lesser ones.

 

[Richard Valladares]

Then what is the benefit to 'Pure Sine Wave' if the power isn't gained for less?

 

[smritte]

There's two basic inverter types and a few ways to achieve them. Square wave and Sine wave. The name Square Wave is normally not referred to other than just a "sine wave" inverter. Where as the other design is referred to as "Pure".

In order to go from 12v DC to 120v AC, the DC voltage must be changed to AC and raised from 12v to 120v. The way they change it is how you get the two diffrent types. This change is where the inefficiency is.

The first inverters made were 120v square wave. It was still considered "AC" even though its not the same "AC" that comes out of your house. Your house would be considered "Pure".
With square wave, motors, lights and heaters didn't care what it was as long as it was 120v AC. Then came computers and appliances with sensitive electronics. The Square wave was too "dirty" and that made electronics unhappy. Pure Sine wave inverters were born. The pure was close to twice the cost of the normal but you needed it for electronics and is very close to what you have in your home.

The answer to your question is, none are very efficient but some are better than others. If you want to run 120v items the inefficiency is the price you pay for the luxury.

 

[Vance Hogg]

Smritte, great post. Perhaps I missed it, but which inverters would you say are on the better side of things?

 

[smritte]

Brand wise I couldn't honestly say. I've played with the older ones and that's it there. I started looking into the diffrent types when I wanted to bring my laptop out with me.
I switched gears on that because I already have mt tablet. Vehicle wise, everything I run is 12 volt. I couldn't justify the expense to have a 110 outlet.

I'm starting to design a battery backup for my house and looking into the bigger ones. One would think it that would be simple. You would be surprised how limited the info is outside of just sales tactics.