Photovoltaic mounting system at the same angle as the latitude of array's location to maximize the annual energy yield of module. For example, rooftop PV module at the tropics provides highest annual energy yield when inclination of panel surface is close to horizontal direction. A study in the tropics showed that the orientation of low-slope rooftop PV has negligible impact on annual energy yield, but in the case of PV external sunshade applications, east façade and panel slope of 30–40° are the most suitable location and inclination. Photovoltaic mounting system Photovoltaic mounting systems (also called solar module racking) are used to fix solar
Injective module proved a useful result, usually known as Baer's Criterion, for checking whether a module is injective: a left "R"-module "Q" is injective if and only if any homomorphism "g" : "I" → "Q" defined on a left ideal "I" of "R" can be extended to all of "R". Using this criterion, one can show that Q is an injective abelian group (i.e. an injective module over Z). More generally, an abelian group is injective if and only if it is divisible. More generally still: a module over a principal ideal domain is injective if and only if it is divisible