I thought I would do some simple math on whether is it now worth it to put solar PV on a building in NZ (in particular Auckland).

So using the stats from my house: Simon & Kristina Cope’s house www.SolarEnergyHouse.co.nz

Feb, 2012

• 70 modules @ 65 W each. ~ 4.55kW, made up of 4 separate arrays feeding into 2 separate SMA inverters with MPP modules.

• Based on 25c/kWh unit and average peak sunshine hours of 3.37 per day throughout the year, this produces ~$1400/year of electricity.

• 8 years ago same system cost $70,000, giving a payback of 50+ years with no interest.

• Today (2012) to purchase modules of equivalent output (but different technology), would cost ~$21,000, with a 15+ year payback.

• If you had $21,000 cash to invest, you have a couple of choices - put money in the bank, or purchase solar PV modules.

- BANK: you would get ~4% ROI from ASB bank – i.e. ~$900 per annum…

- SOLAR PV: you would get a ROI of ~ 6% (excluding tax etc). i.e. $1400 per annum...

You could argue this is better than having the money in the bank…

• If you have to borrow the money, then you pay 6.9% on that money, so although this will cost you slightly more than what you are borrowing, you have two advantages… 1/ price of electricity is going UP (so ROI can only improve), and 2/ It will pay for itself within ~15 years – which is not bad.

Interested in learning more? Contact Simon and come on a tour of the Solar Energy House in Meadowbank, Auckland