Connecting 230V AC to the grid

[bottleveg]

Hello all,
I’ve got a Lister SOM with its original 4.5kva generator. I have applied for ROC/FITS and, if my application is accepted, I plan to connect to the grid.
The generator will produce, I think, 3.6kw. 230v AC. From the research I have done it looks like I will have to fit a grid tie inverter that changes the AC to DC and then back to AC again. Is this correct? If so, any recommendations on what I should fit?

[w0067814]

A certified inverter would be the safest way to do it. An alternative method is to replace the generating head with an asynchronous induction motor.

You can't connect a standard generating head directly to the mains!

-Tim

[KenB]

If you are seeking FITs, your installation will need to be certified.

From an electrical safety point of view, you will at least need to install a G83.1 certified grid tied inverter with full safety interlocks. 

Whilst technically possible with a synchronous alternator ( I have seen it done - and it was brilliantly simple), you will get nowhere with the powers that be.

You better have a good source of fuel - otherwise you will become slave to your 8hp Lister SOM.


Ken

[guydewdney]

Not sure what a certified inverter is.... A grid tie inverter is what its normally called.

Connecting a synchonous motor / generator to the grid will work - but it's not as easy to comply with the rules (known as G83 or G83/1). Do you have three phase or single at the house?

[bottleveg]

Thanks for the replies,
I would prefer to keep the existing generator as it’s the original.
I have registered for ROC before the ‘doom date’ but not been accepted yet.
Fuel is no problem as I eat a lot of chips. I’m already a slave to powering my vehicles, a log burner and c/heating boiler. Maybe were all slaves but we don’t realise it!
My house is single phase. The generator, I think is termed as a ‘whole house’ and was built in ’62 to power an off grid workshop.
I was thinking I may need something like a windyboy but I’m not sure as the genny already produces AC. What I don’t understand is if I already have AC, why do I need to convert it.
 
                            Mark.

[RichardKB]

To feed AC into the grid it has to be in sync with the grid i.e. exactly the same frequency and in phase with the grid.

To be complete the generator or grid tie slighty leads the grid by a nats whisker.


Rich

[bottleveg]

 Ah, so any idea what I need to fit so I can connect? The inverters I have seen all do DC to AC.

[Alan]

All you need is a three phase bridge rectifier.

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0462130

And an Aurora inverter ( Excellent Inverter )

And one three phase isolation switch for the Inverter A.C. side.

Not sure if your generator is three phase or not. If only single phase the bridge rectifier will still do.

You need to check that the alternator has not got any earth faults, simple test with a megger.

The neutral cable on the generator must not be connected to earth.

Regards

Alan

[bottleveg]

Hello Alan, thank you for your help.
It’s a single phase generator. It’s the Start o Matic that Lister built to power 230v off grid properties.
I also found this thread-
http://www.navitron.org.uk/forum/index.php?topic=8160.0
So I must have a grid tie inverter and not just a bridge rectifier and grid isolation switch?
                                 
                           Mark.