In 2016 the Energy Efficiency and Conservation Authority (EECA) will launch a new calculator on its energywise™ web site, the PV Solar Calculator. The calculator has a dual purpose; the first is to allow any householder in New Zealand to evaluate the economic value of PV solar power at their own home, and the second is to educate householders regarding the characteristics of solar power, the importance of how the power is used, and some basic financial principles. The calculator establishes the sun-path for their location, the PV generation profile over days of a typical year, and an energy use profile based on a few simple questions. A report is generated showing energy generation and usage, and various financial measures. The calculator was developed by the authors (originally called the PV Web Tool) with assistance from the GREEN Grid research programme, with the aim of informing the New Zealand public about PV solar power in an unbiased way. This paper details how the calculator works, the assumptions it is based on, and the information required for it to work.