Can photovoltaics really provide a significant proportion of the UK’s mains power?

Barny Evans

I attended a Rushlight seminar last week on photovoltaics, or solar power. As might be expected the general tone was very upbeat. There was talk of the declining cost of PVs, greater efficiency, building integrated PVs and bold claims that by 2100, (the year, not the time), that solar power would be the predominant and cheapest source of power in the world. It was impossible not to be enthused.

From the academic world it was indicated that of the alternative technologies Cadmium Telluride has the most promising immediate future but that the crystalline PVs were likely to be the main source of PV power for the foreseeable future.

We have worked with clients on PV projects and they are indeed offering significant power to some, reducing carbon emissions and providing a very attractive financial return.  However I have always been sceptical of the idea that PVs can play a significant role in the UK energy mix on a national scale.

To date we have installed approximately 2GW of PV and it is proposed we increase that ten-fold in seven years.

Greg Barker, the energy minister, has called for an installation of 20GW of solar PV by 2020 which would equate to about 18TWH per annum or four percent of supply. It is important to bear in mind that to date we have installed approximately 2GW of PV and it is proposed we increase that ten-fold in seven years.

There are some significant issues in meeting this challenge. The biggest by far is the grid both in terms of the way it works and its capacity. On capacity, a lot of the best sites in the UK, Devon, Cornwall, South Wales have significant local grid capacity issues and need reinforcement. This kind of cost is of course often a show-stopper for a PV project, where the cost of local grid reinforcement can be as much as the installation itself. Of course you can move north and east but then the returns start to decline. But these local grid issues may be small beer compared to the issue of how the national grid as a whole manages tens of GigaWatts of solar generation that may be very peaky.

If this is widely distributed then it may be very hard to manage compared to the existing situation with wind where at least they are normally controlled by one party. The National Grid have stated they can take about 10GW on the grid without significant disruption and do have some suggestions to increase demand in the day to match PV supply, but that is unlikely to make a significant difference before 2020.

There is also public perception. As one of the speakers noted 82% of people are in favour of PVs, however I imagine their mind thinks of small rooftop installations helping people reduce their bills, not 20MW farms over tens of hectares of farmland. Local opposition is increasing in some areas and this along with controversy over how we are paying for renewables could serve to make the prospect of a 1,000% increase in current installations difficult.

Having listened to a lot of these views, I am more convinced that PVs can play a significant role in our energy mix but there are a lot of major hurdles that whilst being given lip service, aren’t really being addressed head-on.

Barny Evans is principal consultant, renenwables and energy efficiency, at WSP