Further to my earlier post about Annual Energy Consumption, I want to ask the forum for advice on behalf of the friends who own the house that uses 15,000KWh a year for all energy requirements. I've since found out they do run a smallish woodburner in winter which heats their living room and two small upstairs radiators, so they aren't as low as 15,000KWh year after all!

Anyway they want to generate their own energy as much as possible, and have had a visit from someone from the Energy Saving Trust, who recommended a GSHP and a PV array. My feeling is this is going to cost them a fortune and cause much disruption. They also had a visit from a GSHP installer, who reckons he can install underfloor heating from below the house (it's built on brick piers), but he said it would be a very costly install.

My feeling is they're over egging the pudding and making things way too complicated, and given the fact they are all electric, and have low energy requirements, they should just install a largish PV array, sell the electricity when the new FIT kicks in, and buy their energy back from Good Energy or another green supplier.

If the feed in tarriff for export is say three times the import cost, I was thinking they'd only need an array that could produce a third of their annual requirements, i.e. 5,000KWh. what size of array could produce that in Southern Scotland?

Is my thinking bonkers?

although not too bad as energy users, if it assumed they want to go carbon neutral, it will be far more cost effective to reduce energy usage even further and then go with a green energy tarriff.

Thanks Ted, great info. They don't want to put it on the roof, but in the field above their house, so they can face it directly south. The property is pretty remote. Tell me, does your rough installed figure of 30+K include any grants?

I also thought a wind turbine along the lines of your Proven would be a good option, The field is very open and at 800ft elevation. nPower are trying to build a windfarm a mile away, so I would have thought they could generate plenty of power, but the woman who visited from the energy saving trust said they only had 5.2m per second average wind speed in that kilometre square. I've told then they should get an anemometer on a pole and measure it properly before dismissing the turbine route. Any thoughts on that? What's your annual output from the Proven, and what's your average wind speed?

I'd have a look at interseasonal heat storage if I had enough to buy a 7kW PV system. cover the roof in evac tubes, dig some boreholes and bury heat ready for the winter. (After I'd super insulated my house first!)

Simon

If an existing PV array doesn't currently export to the grid, will it be eligible for these tariffs if it was then decided to get a grid tie inverter and start exporting once the FITs come in, or is this subject to obtaining ROCs, and subsequently, a lower tariff?