DC to AC Conversion

DC to AC voltage conversion. I am having some toruble understanding a couple points. On solar panels DC voltage is produced at some frequency. What is the typical frequency? I know this DC voltage is at some corresponding amperage that when multiplies together gives you power interms of watts. This is fed into a grid tie inverter. The inverter will product AC voltage at the matching frequency from the power utility. Is there a loss of power output that occurs from converting the DC to AC and the matching up of the frequencies? 50 wats in how much AC watts comes out? last question: If a DC motor is turned to creat a DC voltage output and this output has a positive charge on one lead and negative charge on the other lead. These leads are connected to a AC inverter. What will happen to the inverter if the motor is reversed and the polarity is changed on the leads?
- Greg Holleman (age 50)
Richmond Hill GA, USA

The solar panels produce DC, as you say. That means the frequency is zero.

As you also say, the power output is the product of the voltage and current. Some of the power will be lost in the inverter, but I believe their typical efficiency is high.

We have no idea what the output power will be, since it depends on the panels, the light, etc.

It's not a good idea to apply the wrong sign of voltage to the inverter. It may have protective circuitry, but why take the chance?

Mike W.

(published on 10/05/2011)

Picture a water wheel mounted on a pontoon. the pontoon is on a tidal creek. the pontoon can move up and down as the tides come in and out but cannot swing around because of space limitations. The pontoon is kept in place by two fixed poles. As water comes into the creek the inward flow cause the water wheel to turn one direction. The wheel is attached via mechanical linkage to a DC motor which is now generating a DC current. When the tide flows out the water wheel will turn the opposite direction thus reversing the direction the motor is turning. How could I take the output from this DC motor (with changing polarity 2 time per day ) and channel it into a grid tie inverter and not damage the inverter? I am trying to keep the mechanical linkage simple and reliable.
- Greg Holleman (age 50)
Richmond Hill GA USA

The simplest device I can think of would be a diode rectifier bridge. There's a nice illustration on Wikipedia: . You do want to make sure to use big enough diodes to handle the load.

Mike W.

(published on 10/06/2011)