Nuts and Volts

Element - - Finance -

Each PV or BIPV (built-in PV) com­po­nent or ‘mod­ule’ is rated on its peak elec­tri­cal out­put un­der stan­dard test con­di­tions, called the Watt Peak, or Wp. Mod­ules are avail­able in sizes from 5 – 300 Wp, with a typ­i­cal com­plete do­mes­tic sys­tem rated at about 1,000 – 3,000Wp. Ac­cord­ing to The En­ergy Ef­fi­ciency and Con­ser­va­tion Author­ity, a 1kWp so­lar sys­tem costs some­where be­tween $6,000 and $9,000 to in­stall. Ac­cord­ing to SEANZ, which sur­veys NZ in­stall­ers, the av­er­age price in 2011 was around $4,000. Ac­cord­ing to Kiwi PV in­stall­ers Pow­erS­mart So­lar the av­er­age home us­ing 8,500 kwh of power a year could save some­thing like $500 a year if they make the switch, and even more on larger sys­tems. This sug­gests that a PV sys­tem could pay for it­self in some­thing like seven years, if grid elec­tric­ity prices re­main con­stant – and power com­pa­nies continue to pur­chase power from small gen­er­a­tors at the same price. Given the av­er­age power price in­crease of around 6.5% over the last five years, this time could be short­ened. PV sys­tems have an expected life­span of 25 to 30 years, but they do de­grade over time. The best sys­tems are reck­oned to only lose about 0.5% ef­fi­ciency a year, which would mean they should still be 80% ef­fi­cient if the sys­tem it­self is still work­ing 40 years from in­stal­la­tion.

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