The Western Wind and Solar Integration Study (WWSIS) examines the costs and operating impacts due to the variability and uncertainty of wind, PV, and CSP on the grid on the power system operated by the WestConnect group of utilities in Arizona, Colorado, Nevada, New Mexico, and Wyoming. It is an operations study, (rather than a transmission study), although different scenarios model different transmission build-outs to deliver power. Using a detailed power system production simulation model, the study identifies operational impacts and challenges of wind energy penetration up to 30% of annual electricity consumption.

This study was set up to answer questions that utilities, public utilities commissions, developers, and regional planning organizations had about renewable energy use in the west:

• Does geographic diversity of renewable energy resource help mitigate variability?
• How do local resources compare to out-of-state resources?
• Can balancing area cooperation help mitigate variability?
• What is the role and value of energy storage?
• Should reserve requirements be modified?
• What is the benefit of forecasting?
• How can hydropower help with integration of renewables?