Science Questions

Can we sell solar power we generate back to the Grid?

Sun, 7th Mar 2010

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Second Life Listeners asked:

Can we sell the solar power we generate back to the Grid? In countries like Germany and Australia do you get paid decent rates for the power you generate?


We posed this question to Niraj Lal from the University of Cambridge...

I think the economics of it comes down to which country you're in.  I think in Germany a while ago they had a feed-in tarrif, so that means for every bit of energy that you make, that you're not using, you can sell back to the grid at a really high price, a lot higher than what you buy it back at.  So in Germany and in certain places in Australia, it becomes cost-effective to have solar cells in your roof.

I think if you just buy a solar cell off the shelf and put it on your roof in Australia, the payback time is maybe about 10 to 15 years.  But with government subsidies and government programs and you can reduce that to about 8 to 4 years when it starts to become not a bad investment for a household.

A lot of cells are also made from silicon and thatís a pretty energy intensive thing to make.  I think for a standard silicon solar cell panel, itís about 4 years that it takes of making energy in a really nice sunny place to just pay back all the energy that it took to make the solar panel in the first place.  But after 4 years, it starts giving you back in carbon terms and the life of the silicon solar panel is about 25 years plus more.  And so, I think it does start to make sense in certain areas in the world with government help to start off this role.


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Yes, I think the newer ones will only run forwards, but the old ones actually ran backwards. Not only that, but the sockets they plug into do not prevent the meter from being plugged in upside down, which was a method attempted by some people to reduce their electricity bills.

I worked for a company that made RF readers for meters, and our transmitter had reverse detection for the older meters. Geezer, Fri, 12th Mar 2010

On the 1st of April,(I think) People in the UK will be able to feed back into the grid.  A premium will be paid for every kW generated and an additional payment made for every kW exported.  Nearly every household has the capacity to export although most will need an export meter Mazurka, Mon, 15th Mar 2010

Do you know how much they are going to pay in the UK? - in Germany the return is very handsome; in many places it is equivalent priced to the purchase cost when you net use some power.

chris, Fri, 19th Mar 2010

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