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
Injective module group Q/Z and the circle group are also injective Z-modules. The factor group Z/"nZ for "n" > 1 is injective as a Z/"nZ-module, but "not" injective as an abelian group. More generally, for any integral domain "R" with field of fractions "K", the "R"-module "K" is an injective "R"-module, and indeed the smallest injective "R"-module containing "R". For any Dedekind domain, the quotient module "K"/"R" is also injective, and its indecomposable summands are the localizations formula_1 for the nonzero prime ideals formula_2. The zero ideal is also prime and corresponds to the injective "K". In this way there is a