Working out the income and savings as a percentage of the cost of installation, that is about 8 percent return on the installation. That sure beats leaving it in the bank at half a percent. And if in the future, electricity prices rise, that shortens the payback with every rise. If electricity is 13p/ kWhr now, any guesses for what it will be in 10 years time?
Costs are based on our present annual consumption of 8500 kwhr/annum.
We have also done a calculation with the idea that the Solar earth charging might reduce the annual electricity consumption by 10%. Optimistic? but this is what we shall find out over the next two years.