Photovoltaic system and is typically less useful than a calculation of return on investment. While it is typically calculated to be between 10 and 20 years, the financial payback period can be far shorter with incentives. Due to the low voltage of an individual solar cell (typically ca. 0.5V), several cells are wired "(also see copper used in PV systems)" in series in the manufacture of a "laminate". The laminate is assembled into a protective weatherproof enclosure, thus making a photovoltaic module or solar panel. Modules may then be strung together into a photovoltaic array. In 2012, solar panels available for consumers
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