how to count exported pv home electricity

andy_ross

website team CRAGger Glasgow Leamington

Is a (potential) CRAGger actually doing this? If so tell us more!

Andy

If you were being generous to yourself, use UK Fossil electricity at ~-636g/kWh [1]

You should also maybe count lifecycle PV costs: +60g/kWh from all your electricity [2]

So a (slightly generous-to-yourself³) figure would be -636+60 =-576g/kWh.
[4]

NOTES
[1] http://www.zerocarbonnow.org/UK_Calculator.xls
Overall UK electricity is ~472g/kWh but you won’t be shutting down any hydro/nuclear plants

[2] http://www.parliament.uk/documents/upload/postpn268.pdf

[3] But electricity can be wasted if not used and can be somewhat inconvenient to grid-demand planners! This problem would be solved if we all had electric car batteries!!

[4] I’ve had the same issue with potential national exports of electricity
But it’s unclear what figure for an offset to use.
For national electricity exports I used an offset of -150g/kWh (France is much lower, Germany much higher)

[5] CO2 Per kWh of Electricity
France 83
Sweden 87
Canada 220
Austria 250
Belgium 335
EU 353
Finland 399
Spain 408
Japan 483
Portugal525
UK 580
Lux 590
Germany 601
USA 613
Nether 652
Italy 667
Ireland 784
Greece 864
Denmark*881
Source: PriceWaterHouse, EDF, www.manicore.com 2001
(*I have a few concerns about CHP not being accounted for here, but the general message is sound)

john ackers

website team CRAGger Islington

That’s a really interesting question. My initial reaction was yes. But I think it should be zero rated. If you buy electricity through the grid from a decent green supplier e.g. good energy, it would normally be zero rated. However some CRAGS have put a penalty on it (reflecting the fact that there is unsufficient renewable energy in the UK).

I appreciate that the argument is that you are displacing fossil fuel generated electricity. But commercial wind farms don’t get special payments above the market price of the renewable energy they are selling to the grid. Whether CRAGs should offer to pay individuals to promote microgeneration is another thing.

Let’s look at the situation if personal carbon allowances were to be introduced. Assuming it were technically possible, you could sell electricity to your neighbours. But as this is a carbon free source, you and your neighbours would just settle up, as usual, in cash, sheckels or goats; there would be no exchange of carbon units.

angelaraffle

CRAGger Redland Bristol

Thats brilliantly helpful, thanks. The combination of a note of encouragement, some valuable technical info, and the exploration of the principle. The fact that an allowance is an allowance is key. Selling microgeneration is not the same as trading part of your carbon share that you are not going to use. So contraction and convergence principles would dictate that if you export you just get the price (small compared to if you live in Germany) that the national grid pays you for it, but it doisnt alter youre crag carbon accounting.
cheers

Angela Raffle
Bristol
www.sustainableredland.org.uk