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
G-module G-module In mathematics, given a group "G", a "G"-module is an abelian group "M" on which "G" acts compatibly with the abelian group structure on "M". This widely applicable notion generalizes that of a representation of "G". Group (co)homology provides an important set of tools for studying general "G"-modules. The term "G"-module is also used for the more general notion of an "R"-module on which "G" acts linearly (i.e. as a group of "R"-module automorphisms). Let "G" be a group. A left "G"-module consists of an abelian group "M" together with a left group action ρ : "G"×"M" → "M"