As the OECD Competition Committee highlights, this intermittent generation therefore raises the challenge of how to maintain the balance of supply and demand when renewable supply varies (OECD Competition Committee, 2010). A more flexible allocation of power production can enhance the ability of the electric system to accommodate high shares of renewable energy. This is an advantage of wholesale markets over power purchasing agreements, which -despite their convenience - reduce the flexibility of the power park to adjust rapidly to sudden increases in renewable energy production. Many factors enter in the choice of which technology will be used to match supply with demand (e.g. cost of production, ability to ramp up or down the power supply, etc.).