The differences between countries are due to differences in load factors and the cost of back-up capacity. The system costs of the three key technologies increase from onshore wind to offshore wind and solar PV. These system-level costs come over and above the higher plant-level costs of renewables. Including the latter, based on the figures contained in the 2010 IEA/NEA study on the Projected Costs 0/ Generating Electricity as well as more recent figures for solar power, increases total generating costs by up to 30% for onshore wind, up to 50% for offshore wind and up to 200% for solar energy.