8.8 Ancillary services to cater for solar intermittency

When industry experts discussed ancillary services, they asked how much spinning reserve would be needed to support intermittent generation. Some experts believe solar intermittency can be compensated in the same way as for wind. Others believe an evolution of ancillary services is required, which include demand response and management, control of power flows, dynamic voltage/Var control, integration of energy storage, aggregation, etc. Accurate forecasts feeding into dispatch will assist in managing regulation plant and ancillary services market.

Industry experts were asked whether intermittency has an influence on the financial position of solar generators, and most of them believe it does. Information investors would need in order to provide better solar generation certainty includes:

  • methods of mitigating power quality impacts from the connection of solar generation
  • data on solar resource/measure of solar irradiance at site of solar generation which would be an assessment of energy production across a period of time, e.g. a year. A view of firm energy output would be required for contract purposes
  • orientation of solar power plant
  • knowledge about the capability of the network to sustain the solar generation during its intended hours of operation
  • energy storage information. Some storage would be strongly recommended for the investment to compensate for intermittency.

Many people believe that existing mechanisms cannot adequately handle short-term fast fluctuations caused by variable solar resource and other environmental factors. There could be a need to investigate the possible rates of change of power and the performance of the network due to solar intermittency in order to determine the type of ancillary services required and to determine whether existing mechanisms are sufficient for intermittency compensation purposes.