We installed an Eoltec Scirocco 6 kW grid linked wind turbine in November 2008 on our well exposed small farm in the west country. This is producing about 6000 kWh per year, which is rather less than the estimate based on the NOABL database figure for our grid square. That said, I do not know how windspeeds in the period of operation compare to the long-term average, and can’t easily find out (this could be a separate thread!).

We have installed as many low energy appliances as we can and have got our daily consumption down to 7.8 kWh per day (best month) – and we work from home. Despite the fact that we produce more than our annual requirements, in practice we export 68% of the energy we produce – because inevitably are electrical use and production profiles do not match.

This brings us on to the FiT. We installed before July 2009 and so get the ROC equivalent, of 9p/kWh generated, with just 3p/kWh for our exports (down from 5p). This is derisory, but that is what has been decided and there does not seem to be any sign of change with the new government. As a result, we really need to use as much of the power that we produce right here, to avoid exporting it, as it is more valuable to us than 3p/kWh! How do I do this?

After a lot of investigation, it seems that the best way to do this is to invest in an EMMA from Coolpower in Ireland. This device monitors the export of power from the inverters and switches in resistive loads (I believe uses sophisticated thyristor control) as necessary, almost eliminating exports. I am therefore thinking of a storage heater in one room and the immersion element in our 850l thermal store. The latter is heated by a wood fired range cooker and an oil fired boiler and has a cooling function so that if it gets too hot, the CH powers up to dissipate the excess heat.

The thermal store is designed for solar and we have put a hold on purchasing solar panels because the house is listed. In view of the way the Fit has gone, I feel that we should use the EMMA to make the best use of the 4000kWh that we would otherwise export and I believe that it will be cheaper than the solar panels we wanted. It will save us on oil too, and as it is windier in the winter than the summer, the energy production profile should also better match our demand profile.

Any comments?

Hi Evan,

Interested to know how you worked out when you are exporting? Some sort of clip on current sensor on the supply to the house or does the inverter have an output?

The EMMA works out when the export is going on and powers the loads accordingly to take up what would have been exported - or so I understand. no idea how it does it! Haven't got one yet, hence getting other views! It does seem like a good solution, and for folks with PV too, not just wind

Why are immersions bad? do you mean generally when used in a normal home, importing grid lecky? or is there some hidden evil I don't know about which means they shouldn't be used with renewables?

You could put your freezer on a timer and set the temperature so it is as cold as possible. That was when you are using the least it can be set to turn on, helping to balance your load. Same with hot water and the storage heater. Think of everything that you can run when you are not in or at least not using power and set them to turn on then. What is your mean wind speed according to NOABL as it does seem a bit low, though there are many other factors involved. Maybe a separate thread for everyone that self generates to post their numbers on is a good idea.

Posted By: MartinHGenerating hydrogen would be a nice idea though, or charging a battery bank and getting a smooth output from inverters.

I thought you still got huge losses from these systems. I recall hearing that you only get half the power out that you put in. So, your lost opportunity export is twice as expensive (if you follow my drift). Financially it still makes sense, but cut's the "margin" especially when having to pay for the kit and replace batteries.

How about getting some PV installed under the FITs and then feeding your wind power into it. Slightly dodgy but may get away with it.

Mark

As for fridges/freezers not having enough storage to last long enough, same timer could also be used to come on every hour for 10 minutes or something similar. Though the energy used by a freezer is not that great. An all electric Power Shower could use a fair bit and could be used when the wind is blowing enough to fully supply it.

Seems it is all about timing your choices rather than financial outlay.

Posted By: SteamyTeaAs for fridges/freezers not having enough storage to last long enough, same timer could also be used to come on every hour for 10 minutes or something similar. Though the energy used by a freezer is not that great.

Does the EMMA support this kind of functionality? I.e. have something on full time when the renewable energy is surplus, but pulse it when it isn't.

Posted By: SteamyTeaAn all electric Power Shower could use a fair bit and could be used when the wind is blowing enough to fully supply it.

True, but most people want to have a shower when it is convenient, not have to wait until the sun is up and shining strongly enough or the wind is blowing. If you were so motivated then it is easy to time your shower manually. I for one wouldn't want to be halfway through a shower, all soaped up and find the shower cut out because it started raining. The neighbours might get a bit of a shock when I went outside to wash the suds off....

Posted By: SteamyTeaSeems it is all about timing your choices rather than financial outlay.

Precisely.

I don't know how much that costs, Martin?

Also: yes, buy an electric vehicle. I have a van and a car and a bike, can soak up plenty of energy. Unfortunately I can't have any renewables on my rented house..

I agree entirely with Mark B's view that the FIT is not well set up - I would prefer to be paid a bit more for export so that others on the grid can benefit rather than me using it all. That said, I would be offsetting oil use, and the UK is having to import an increasing amount of oil is N Sea oil stocks decline. How we pay for that imported oil with a trade deficit like ours I do not know. As for the future....

A 6 kW EMMA is about £1700 (depends on the value of the Euro!), so the payback is of the order of 7 years at current electricity prices. I would say that that is pretty reasonable. There is a smaller 3.6kW version which could be used but you would end up exporting more when it reaches its limit.

wrt to running large loads when its windy - we do this to a limited extent, as we can see the turbine twirling away as it in view of the house. Timers are only OK for PV.

If the objective is to maximise your own use of the renewable energy you generate, and minimise your utility bills regardless of whether it is the best option for the environment or not, then the EMMA technology looks good. In this case, I would think that immersions in the thermal store are probably the easiest way to go and then to use this to provide space heating and DHW.

If more energy is available then an electric shower, or in-line electric heater might be worth considering. This way you don't get the storage losses from a large, hot thermal store, but you are limited on flow rate and getting hot water when the sun isn't shining and the wind isn't blowing.

You could also consider one of those fancy vacuum flask/kettle/hot tap Qooker thingies to make sure your piping hot water for your tea/cooking is heated from renewable energy.

I don't think it's the way I would go, but each to their own.

As far as I can see, whether you are on RoC or FIT makes absolutely no difference to this discussion. I appreciate that for RoC you get less for generation, but that is the contract, you were aware of the rate you would get at the time you signed up and I don't see it changing any time soon. Feel hard done by, fine, but don't let that affect your decisions over what to do with your excess renewable energy. The export rate for both RoC and FIT is 3p/kWh, so the incentive/disincentive is the same and the decision should be the same for both.