Grid tie 230VAC water turbine

[qeipl]

Hello,

I'm attracted to the idea of connecting one of Navitron's 750W high head turbines to the grid.
I've been reading this forum (and elsewhere) to get the gist of the concept but some of it is still a bit hazy so if anyone can answer any of the following I'd be very grateful...

1. I'm not interested in exporting (I can use all 750W). Do I need to get a new mains meter or will the existing one be happy with a supply appearing on the consumer side of it?

2. The turbine produces 230VAC. Is there a G83 compliant way of connecting without having to rectify to DC and then go through a GTI (e.g. Windy Boy)?

3. If I have to go down the DC/GTI route can I use a simple bridge rectifier (e.g. http://www.reuk.co.uk/Buy-35A-Bridge-Rectifiers.htm ) between the turbine genny and the GTI or is there more to it than that?

4. Any comments on the reliability of GTI kit? Does it 'trip out' regularly? Does it need lots of fiddling and faffing about or is it 'fit and forget'?

I have spoken to the DNO who have sent me the relevant forms. They're not interested in the detail of the installation other than getting a signature to say that it's G83 compliant.

Thanks,

Malcolm

[guydewdney]

1) At three AM - the turbine is running, and you are using 50 watts - what happens to the rest? It has to go somewhere. You have two basic choices. 1) export (cheap, easy, infinite capacity) or a load controller (complex, expensive).

In order to connect to a GTI you MUST have the ability to export. The export meter is 7 quid (from universal meter services). You get paid 10 pence per unit exported - why not?



2) no. Unless you use the power to run (say) the lights. Then you need a load controller to get rid of the excess.

3) yes. You can. BUT - if there is no load on the turbine, what happens? Most are OK with overspeeding, some are not. The rectifier I have is also an over speed controller - but you may well not need this.

4) mine has required adjusting to the power characteristics of my water wheel. But then its a bit of a special case. It does not trip out. I have an Aurora inverter.

[Richard Owen]

The Navitron web site states that the high head turbines come with an integrated dump load and controller.

So, I don't think there's a problem in not using the generated electricity: you just get to warm up the tail race slightly.

This makes things significantly simpler, but it does seem a pity not to get maximum value from exporting any excess.

[camillitech]

Hi Malcolm,

If you can use all your 750w constantly then just connect it direct to the turbine and don't bother with the inverter carry on as the turbine has a very effective load control built in but like Guy and Richard say if your not using it all the time it seems a bit of a waste.

Cheers, Paul

[qeipl]

Guy:
As Richard says, the Navitron turbine has its own dump load so no additional controller required.
In the winter at 3am the hydro output will be keeping me warm and making sure there's lots of hot water for a morning shower.
In the summer at 3am or when the sun's shining a lot, you're right, wasted power. I'll investigate the export option.
I've seen an export price of 4.5p/unit. Who's offering 10p?

Paul:
My main electricity use will be an air source heat pump that is built onto a big hot water cylinder. Around 800W electricity in gives around 2500W of heat out.
The burn will easily do 800W when it's raining but only around 500W in dry spells so I can't connect the turbine directly to the ASHP.
Grid tie is more attractive than charger/battery/inverter for making up the difference and it means the turbine output is being used for other things when the ASHP isn't running.

[guydewdney]

10p = goodenergy.co.uk for everything GENERATED not exported

[qeipl]

Found goodenergy. Looks promisingly straightforward. Many thanks.

[Paulo]

Hi Malcolm,
Sounds like you have the same queries as me. I think you may also be looking at the same heat pump. One query I have about heatpumps is start up current this can be 10 times the running current - have you considered this, and if so, could you post the details of the equipment?

Guy,
Could you provide any details of your rectifier? Is it off the shelf or custom made? I'm not convinced the reuk bridge rectifier will do the job with single phase. Anyone know for sure???

Cheers,
Paul

[guydewdney]

It came with the old generator heads I no longer use. They are beefy things - with screw terminals. No further info on them. The heads are 2.5kw rated at 500 volts - so I guess the rectumfriers are too.

renewable energy components up in scotland.
look like this
http://cgi.ebay.co.uk/75Amp-Bridge-Rectifier-Converter-3-Phase-DC-SKBPC-1000V_W0QQitemZ350153228024QQihZ022QQcategoryZ36332QQssPageNameZWDVWQQrdZ1QQcmdZViewItem


Or just buy four bfoad diodes?
http://www.rapidonline.com/Electronic-Components/Discrete-Semiconductors/Rectifier-Diodes/10A-Standard-recovery-rectifier-diodes/79498/kw/diode
10 amp rated?


want bigger?
http://cgi.ebay.co.uk/Bridge-Rectifier-3-Phase-DC-127A-1200V-VUO-110-12-NO7_W0QQitemZ150322176993QQihZ005QQcategoryZ36332QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[billi]

Sad enough that there is no real answer  upto now , well except my offgrid idea would work   easy  

One query I have about heatpumps is start up current this can be 10 times the running current

Billi

[qeipl]

Paulo,

If you grid tie the turbine the heat pump start-up current isn't a problem - the grid gives you the necessary oomph.

I've been warned by one opinion that a simple rectifier will deliver a current that is too spiky for the Windy Boy. He recommends adding a capacitor to the circuit (smoothing capacitor?), the implications of which I have yet to investigate.

Another opinion says 'try it and see'.

I have yet to consult my electronically-educated chums so have yet to come to a conclusion. I've been too busy buraching about in the muddy swamp that is the site for my turbine shed.

[qeipl]

You may all have found your own answers to the rectification question by now but as my system has been running happily for a couple of weeks I thought it worthwhile reporting the following:

Navitron 750W high head turbine (76m head; 370m of 76mm pipe; insert reduces nozzle from 26mm to 13mm diameter)

REUK bridge rectifier rated at 600V.

500V 2200microFarad smoothing capacitor connected in parallel across the output from the rectifier.

Windy Boy 1100 grid tie inverter.

The inverter appears to be perfectly happy with the output from the rectifiier.
Neither the rectifier or the capacitor get unduly warm (the rectifier is bolted to an aluminium heatsink).

The capacitor was sized using this formula and then adding a bit for luck.
http://www.kpsec.freeuk.com/powersup.htm#smoothing
Verified by an engineer as the correct procedure.

[billi]

Class , well done

Billi

[camillitech]

Well done Malcolm,

I heard you were short of pipe after an epic sea voyage  but obviously you got it sorted.

Cheers, Paul

[qeipl]

<<I heard you were short of pipe after an epic sea voyage  but obviously you got it sorted.>>

They handed me a rope with 400m of pipe attached. Allegedly. When I got it home it was 330m. I didn't fancy another 80 mile round trip so I managed to scavenge enough bits locally to make up the difference.