Sunday, December 1, 2013

In Praise of PV Solar

While still backing nuclear (although not the current type!), the Guardian’s George Monbiot had a go at PV: ‘If every square metre of roof and suitable wall in the UK were covered with solar panels, they would produce 9% of the energy currently provided by fossil fuels’.

No one suggests that PV could meet all our energy needs. But UK PV trade lobbyist Solar Portal has suggested that PV on only 1% of total UK land area could meet all the UK’s electricity needs: 

That may be oversimplified, and it does mean building a lot of solar farms, but the general point is clear- PV could supply a lot of electricity. But so could wind, on and offshore. And wave and tidal. Which means that, since we could at times have a lot of surplus green electricity,  some of the PV output could perhaps  also be used supply some heat, thus saving gas.  You could for example run the spare PV electricity into storage heater system or an immersion heater. See for example There are also some interesting PV-thermal hybrid systems emerging which absorb heat as well as light. The technical point is that PV cell efficiency falls of with rising temperatures so it is helpful to cool them. Adding a solar heat absorber does just that, increasing the units overall energy efficiency dramatically. Naked Energy’s ‘Virtu’ hybrid PV/solar thermal panel is claimed  to be able  to supply ~ 3 times as  much energy (as heat and electricity ) as a normal PV panel of the same power rating.

Surplus PV electricity can also be used to charge battery Electric Vehicles. So it would be offsetting petrol use too. It is also possible to used PV electricity make  hydrogen by electrolysis and from there you can produce synfuels for vehicles. So there are technologies that would allow PV to meet heat, power and transport needs. Not all of them, but some.

How much can we expect? Last summer the UK’s then 2.3 GW of PV briefly supplied  about 2% of UK electricity. By 2020 DECC say PV might expand to 10GW or even  20GW in the UK, in which case, on these figures, at times it might supply up to around 23% of UK electricity, although by then demand may have risen slightly, so say just 20%.  For comparison, Germany has 32GW of PV at present, which sometimes supplies nearly 50% of its electricity needs.

Globally there is over 100GW of PV in use, and its adoption in accelerating, as costs fall.  The World Energy Council notes that in one its new scenarios ‘by 2050, globally, almost as much electricity is produced from solar PV as from coal,’ and Shells recent Oceans scenario envisaged solar as being the largest single energy source globally by 2060. Large and small, PV looks good.

That said there are some drawbacks. PV cells don't work at night and light intensity varies a lot during the day and over the year. That means that there will be a need for costly backup and grid balancing if there is a large PV contribution, much more than is needed for wind, which is often strong at night and certainly during the winter when energy demand is high. But PV does match well to some energy loads- daytime offices and their summer air-conditioning especially. And as cost continue to fall, and grid balancing and energy storage systems spread, PV can make a significant contribution.

Interestingly, the Solar Trade Association (STA) claims that the cost of PV will fall below the £92.5/MWh CfD strike price set for the proposed new Hinkley nuclear plant by 2018- 5 years before its expected to start up (in 2023) if it get EC permission.

DECC seem to have backed a looser there. And that is assuming all goes well with getting the finance for Hinkley agreed with the EU and then getting the plant built without delays. It could be a lot later and the price could escalate, as has happened with the EPRs being built in France and Finland.  For the UK, the tragedy is that under the CfD 35 year contracts, consumers will be locked into paying (EDF) for it until 2058, assuming a 2023 startup! The STA may be optimistic in its forecast for PV cost reductions, but by 2023, PV and on-land wind do look like beating the Hinkley CfD price and offshore wind shouldn’t be far behind, followed a bit later by wave and tidal. And by 2058, if it goes ahead, Hinkley is going to look decidedly out of place- with supposedly 25 years more then still to run! Maybe it will go bust and be shut early, and the large site will be converted in to solar farm or wind farm…We could of course do that now and avoid paying £1bn a year to EDF for it!  Amusingly, that's just what UK PV company Lightsource has suggested. It wrote to David Cameron claiming that PV could match the output of Hinkley within two years at comparable cost.

That may be overstating the case, but it does look like PV is going to be big, even in the  cloudy UK. And maybe bigger than nuclear, with, as in Germany, much of the running being made by individuals and groups buying into it. Half a million UK consumers who had enough disposable income have already invested in PV systems- bringing the total to around 2.7 GW so far. It’s cold just now in wintery Britain, but sunny. Good PV weather. And PV can only get better.


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