Photovoltaic system in northern climes to 5.61 kWh/m²/day in the sunniest regions. For large systems, the energy gained by using tracking systems can outweigh the added complexity (trackers can increase efficiency by 30% or more). For very large systems, the added maintenance of tracking is a substantial detriment. Tracking is not required for flat panel and low-concentration photovoltaic systems. For high-concentration photovoltaic systems, dual axis tracking is a necessity. Pricing trends affect the balance between adding more stationary solar panels versus having fewer panels that track. When solar panel prices drop, trackers become a less attractive option. Systems designed to deliver alternating
What Is a Nation? What Is a Nation? "What is a Nation?" ("Qu'est-ce qu'une nation?") is an 1882 lecture by French historian Ernest Renan (1823–1892), known for the statements that a nation is "a daily referendum", and that nations are based as much on what the people jointly forget, as what they remember. It is frequently quoted or anthologized in works of history or political science pertaining to nationalism and national identity. Renan wrote "What is a Nation" in order to symbolize the nationalism which was born in France as a result of the French Revolution of 1789. Renan begins his essay by noting