Solar Energy UK examines adequacy of British grid

Solar PV in the U.K. has by far exceeded all expectations and the government has been left trying to catch up with the market developments, said Ray Noble, an advisor to the U.K.’s Department of Energy and Climate Change (DECC) and National Solar Centre (NSC).

What is even more outstanding, Noble added, is that photovoltaic farms are outperforming, making solar in the U.K. a worthy investment.

The DECC expects about 8 GW of PV installations by 2016 and 12 GW of installed capacity by 2020. This will come through various schemes such as the feed-in tariff (FIT) — FITS will be reviewed in 2015 — the Renewables Obligation Certificates (ROC) and the new Contracts for Difference (CfD) program starting in April next year. Household, commercial rooftop projects and ground mounted farms are all on the rise, with councils also starting to enter the market to develop community projects.

But is the U.K.’s electricity grid ready to cope with PV’s stellar success and how transmission and distribution grid operator practices affect their assets’ performance and generating income? A few Solar Energy UK sessions touched on the subject.

Unfortunately, solar PV power curtailments are necessary at the moment, said Steven Gough, innovation and low carbon networks engineer at Western Power Distribution, a distribution network operator (DNO) in Southwest England.

The main objective of DNOs is to maintain the smooth operation of the electricity grid and they do so by applying active power control. Of course, the best option is to reinforce the grid, but this is a costly option and developers cannot always pay for it.

Should a developer pay for a grid upgrade, for instance buying the transformer for a substation, this would be owned by the DNO. However, some developers tend to invest in grid reinforcement aiming to maximise their asset maximum power output.

Grid reinforcement also needs to satisfy certain criteria set by Ofgem, the U.K.’s energy regulator. Ofgem does not want grid reinforcement expenses to affect the consumers electricity bills, said Tamar Bourne, who worked to develop the Renewable Energy Grid Collaboration Service in collaboration with large scale developers and the Western Power DNO.

DNOs will agree to electrify solar PV plants without grid reinforcement, but they should always advise their customers that their asset power output will often need to be curtailed in order to maintain the security of the grid, Gough pointed out. An additional solution to this problem could be utilising energy storage, but although the energy storage technology exists, this is not currently happening due to a series of regulatory barriers. The DECC needs to set out the energy storage legislation for this solution to power curtailments to be utilised, Gough added.

An additional concern raised recently by various market stakeholders regards the quality of grid connections. Developers are rushing to finish their projects before the CfD mechanism enters into force in April 2015. There are therefore concerns that the engineering work connecting projects to the grid is happening very hurriedly and, as a result, clumsily. Gough, however, told pv magazine that his experience does not confirm such concerns.

Renewable Energy Grid Collaboration Service

Bourne said grid limitations in Southwest England have led to the creation of the Renewable Energy Grid Collaboration Service, which she now manages on a day-to-day basis.

The service brings together developers sharing information and eventually helping them to set up consortiums, thus enabling them to apply for grid connection as a group. That way, Bourne said, developers can share the costs of connecting to the grid and/or reinforcing it. Establishing such groups is a complicated process because not all developers share the same needs or project time framework. But the signals so far have been very good and the service is ready to expand, aiming to unlock capacity that otherwise would need to be curtailed due to lack of grid infrastructure, she said.