Ian McLean Spokesperson for the Green Party

Here are a few simple facts on solar electricity generation. Depending on where you live, a typical solar electricity generator on your house will deliver $1000-$1200 worth of electricity every year at today's prices.

Ignoring interest costs on borrowing, it will pay for itself in eight to 10 years.

Your house offers most of the infrastructure needed to build that generator. The only additional equipment is the generator itself, which you can buy for the same price as a small three-year-old car.

During 10 years, that car will decline in value to almost nothing and deliver increasing running costs.

In contrast, the solar generator pays for itself, costs almost nothing to run, does not wear out, and will supply electricity for at least 25 years.

At today's prices, the solar system represents an investment with a tax-free annual return of about 10 per cent.

If electricity prices go up (and they always do), the return increases. While interest rates remain below 10 per cent, solar even makes economic sense on borrowed money.