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Grid Tied Generator? Answered

So I am planning on hooking up a grid tied inverter and generator, I still need to measure the voltage on the incoming lines, but I assume it is 120 ish so I think that is were I will hook the inverter and then it will go back out through the transformers into the lines, is this right?  Now lets say it is hooked to a wind turbine, will the amperage on the generator vary with the speed while still supplying the right voltage, if not how do I compensate for varying wind speed.
We are talking 29 kw generator (it is huge, 16 more than the max on my meter, I will obviously consult the electrical company.


When connecting a generator to the grid, you MUST go through approved equipment which will synchronize the power you're generating with the phase of the grid -- both to protect everyone else and to protect your equipment. This is a purchased device. It's usually combined with a modified electric meter which is specially designed to track power you're selling to the grid -- again, that's something you MUST obtain from your power company.

Yes, a typical generator's output in both amps and volts varies with the speed it is being turned at. Again, you need intermediate circuitry which will take whatever is currently coming in and boost it to line levels before you attempt to feed it back into the grid.

This is pretty standard off-the-shelf equipment these days, since home generation/cogeneration are becoming more common. Your electric company can undoubtedly point you to electricians/contractors who have experience with this and can help you spec out the best solution for the interface.


7 years ago

A friend of mine got on to grid. Here is a very important Safety you must consider.

The dropped out power line that happens when a power pole hit by a truck or another accident cuts all wires.
The power company repair man comes to fix the situation.
He knows the Live side and he thinks the other side is unenergized
(  a dead line ) is safe for him to work on.
But your generator is ON the so called unenergized side and kills the repair man.
Now you could be charged with manslaughter.

Your system must sense a dropped power line condition and disconnect itself...

Like orksecurity says, "you must go through approved equipment".

By the way the electronics to do this ain't as hard as regulating the generator.


The safety electronics isn't difficult -- but for obvious reasons they aren't going to trust a homebrew solution, and I wouldn't either. Hence the requirement for approved equipment. Neither they nor you want the liability risk.

Steve: Yes, they have to buy... but the rate they pay per watt is not the retail rate. (Currently, at least in our area, it's somewhere between the retail rate and what they're paying wholesale from major generators.) The meter runs backward at a different speed than it runs forward... and it has to be a meter specifically designed for the purpose, since older meters were specifically designed NOT to run backward to prevent attempts to tamper with them.

They are offering STUPID completely unsustainable "feed-in" Tariffs over in the UK for renewable juice - some multiplier higher than the market rate for ordinary juice.

Interesting point about the meters - ours WILL run both ways !


Here inthe US, the power grid is starting to realized that distributed and diversified sources are Absolutely Necessary to take some of the load off the main "backbone" power lines, which are already running near capacity. (Hence the blackout cascades we've gotten where one line going out causes too much load to be shifted to others which also go and so on... though the system is smarter about that than it used to be.) Combine that with energy efficiency/independence incentives and it's not a bad time to be considering things like household solar and so on.

(I _almost_ bought a household cogeneration plant, back when I upgraded my heating system. But at that time the unit I was interested in was only available for forced-hot-air, and I wasn't going to replace my hot-water system nor was I willing to wait.)

Hi A.

Have you any links you can send me on the topic ? I've been interested in the circuit topology of grid tied inverters for a bit, but not found a right lot out there.


Over more then 20yrs ( i don't really care to think how old )
Anyway we were running early SCR self commutated inverters
( we had a patented transformer to minimize the third harmonic ).

The specially wound motor had to move 10 ton logs to 1/8'" very fast for a lumber mill set-works before a huge band-saw.
The operator was jogging the log as it approached, these conditions dumped serious power to our electronics..

We purchased a rather sophisticated ( because it had two doors :-) 90kw GE four quadrant DC supply. The motor regeneration was too much for fanned resistors banks
and the GE unit would quietly take any excess DC power over the set level and parse it back into our buildings grid a 3 phase mains all the while maintaining a steady reasonable power factor.
We made Mistakes and that GE cabinet handled it all without a problem, ever..
As I recall we were on the end of an industrial power line that was not well controlled and the GE cabinet handled that too.
Nor do I recall any hassle with the power company about using their 200mile grid.as our private overage
I suspect the GE 90 kw unit was already ork style approved equipment because after building electricians hooked it up ( Wired it into the mains ) a single man checked on us for 15 minutes and left us to have a good time away from the office

We did a small installation and I will be looking for all log books and pass you what i find.

Jack who did this with my help was a simple windmill a rear differential to send shaft power to a self excited induction motor.
We appropriated the differential from a turned over rusty van in the desert
The output of the generator was fed to rows and rows of incandescent light bulbs in the crawl space under Jack's house.
Here is the beauty of the system, there was no regulator except the house thermostat..
When the wind blew strong the light bulbs ware almost bright and heating under the house and the thermostat had to reduce the gas furnace by 1/2
( Saving Propane fuel ).
When there was no wind the thermostat heated the house normanly..


Its interesting Ork comments about the utility needing to install special equipment. Here in the UK, they HAVE to buy what you have to sell, and the meter just goes backwards.