Solar power growth impacting UK electricity sector

Q2 of 2015 saw a large increase in the generation of electricity from solar PV in the UK, with the growth having a significant impact on electricity market prices and other supply factors.

Figures included in the second quarter GB Electricity Market Summary from energy data specialist EnAppSys showed that solar PV recorded a 153 per cent increase in electricity generation compared to the same period in 2014.

Paul Verrill, Director of EnAppSys, told Power Engineering International, “Renewables are playing an increasingly important role in meeting Britain’s energy needs and as the contribution increases, it must be assumed that its impact on pricing and supply issues will continue to grow.
Paul Verrill
Although at 1.37 GW solar PV represented only around 4 per cent of Britain’s 33 GW total power generation during the April-June period, it was noticeable that this was the first quarter in which solar has made a significant contribution to national output.

Overall levels of electricity demand remained largely unchanged during the period, but changes in supply saw seasonal falls in levels of wind and hydro generation, with output from coal declining as a result of a combination of increases in the carbon price support mechanism and the start of summer maintenance outages.

Overall, during Q2 2015, CCGT produced 27 per cent of overall electricity generation, with coal-fired power plants providing 23 per cent, nuclear 22 per cent, wind 9 per cent, interconnectors 8 per cent, biomass 5 per cent, solar PV 4 per cent and hydro 2 per cent.

However, with overall solar capacity now put at around 7 GW, other power generators are having to adapt to rapidly changing market prices at different times of the day and facing the need to adjust operations to avoid oversupply inefficiencies and related cost penalties.

One market impact of this during the second quarter were periods of negative prices, particularly overnight, but with the system also being oversupplied during some daytime hours when levels of solar output were high.

“The recent instances of negative prices have shown that the system can be slow to react to demand and the wider mix of generation sources is something that traditional power generators and the National Grid will have to react better to,” says Verrill. “For example, we have recently seen the surprising instance of six different combined cycle gas-turbine power plants (CCGT) and six coal stations remaining online overnight despite lower prices.”

“It is unlikely that the overnight price loss from oversupply will be compensated by increased daytime demand, which suggests some price insensitivity in the market and the likelihood of further negative power prices in the near future.”

“If the capacity and output of solar PV and other renewables continues to grow, conventional power generators such as CCGT and coal will have to be more flexible to avoid oversupplying the network and paying the penalty of negative power prices.”


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