how do they do it?

[rfs100]

Lately, the Hydro people here have been offering to "buy back" electricity from individuals that are generating their own power. We all know that you can simply stuff electricity back into the power grid the other way around. Supposidly they supply the equipment to interface you into the grid
So how is it done???!!

 

[tcmtech]

Around here our local power company just lets the meter run backward to offset your own electric bill. However if you can regularly generate more than you use a month they set up a dual meter system or one of the new digital meters that reads the KWh's for each direction and then figure your bill or payment from there or so I have been told.

As far as the actual back-feed method is concerned there are numerous ways to do it. The two most common are either by electrical mechanical means using a dedicated synchronous generator or over spun induction motor or electronically with a grid tie inverter system. Stable higher power sources most often use the electromechanical methods and the smaller highly variable power like small scale wind and/or solar tend to lean toward the solid state methods.

Personally I use the home built grid tie inverter method myself of which I have several threads here now relating to the basics of how its done on the power handling circuitry side of things. But ultimately I leave the builders to deal with the safety and legality issues themselves though. I just show how to make the power go back-wards.