Solar PV is changing the dynamics of electricity systems globally, and Ontario is no exception. A new report by the Independent Electricity System Operator (IESO) shows that solar PV, particularly distributed solar, is impacting Ontarios grid in multiple ways.
Ontario currently has only 280 MW of solar PV connected to the transmission grid, with another 100 MW planned to come online over the next 18 months. Over the same period IESO predicts that behind-the-meter or embedded PV will rise to over 2 GW, and behind-the-meter wind to around 700 MW.
This is a particularly large volume of distributed generation for the size of Ontarios grid, and during the spring behind-the-meter wind and PV met from 4.7%-6.6% of monthly demand.
IESOs 18 Month Outlook to December 2017 finds that the level of peak demand over this period will remain flat, as behind-the-meter solar and wind and conservation programs offset increasing demand from population growth and economic expansion.
This is particularly true for solar, which IESO finds produces at high levels during the periods of summer peak demand, which are higher than winter peak demand. Growth in embedded solar and wind generation capacity and on-going conservation initiatives reduce the need for energy from the bulk power system, while also putting downward pressure on the peak electricity demands, finds the report.
IESO also notes that increasingly solar is also changing the profile of net demand. Embedded solar is not only reducing the level of the summer peaks, but is also pushing the peaks later in the day, states IESO.
As the resulting net demand to be met is later in the day, solar is less able to supply capacity value. This has occurred in other grids, most famously in California, where the duck curve effect is driving the need for fast-ramping generation and energy storage.
Additionally, with an electricity mix dominated by inflexible nuclear power plants and a high portion of wind and solar IESO is having to take technical measures to balance these incompatible resources. The agency reports increasing curtailment of both wind and nuclear power.
Such issues may get more intense the future. A week ago, Ontarios minister of Energy increased the target for the second phase of the Large Renewable Procurement to 980 MW, by re-allocating 50 MW of capacity from prior procurement targets that had not been met.
ISEO has identified the need for more frequency regulation, resource flexibility to manage supply and demand, and voltage control. It is unclear how much of this is related to the provinces generation mix, however some of these services can be supplied by PV plants equipped with advanced inverters, and others with battery storage.
These findings reinforce the need for a robust portfolio of resources that contributes to the continued reliability of the grid, notes IESO in a press statement. The IESO is taking steps to meet these needs.
Ontario has intermediate and peaking generation needs met by gas, oil and hydro plants with storage, and additionally provided 10-year contracts to nine energy storage projects totaling 17 MW at the end of 2015.