Whether to use solar panels or not was another choice we had to make. It is very difficult making this choice because there are so many variables. The Clean Energy Council of Australia has a very good website that talks about solar panels which is here http://www.cleanenergycouncil.org.au/cec/resourcecentre/Consumer-Info/solarPV-guide .
For us the equation was whether our mortgage plus our electricity bill would be smaller or larger if we chose to use solar panels. If we were to use solar panels, on a house we intended to stay in for a while, then it seemed that it was more efficient to choose a more powerful system over a smaller system.The size of the system is limited in many cases by how many solar panels can be placed on the roof. Using a panel size of 1600mm x 800mm I guestimated that a 4 or 5 kWh system would fit. With this information I went to a website called Solar Choice http://www.solarchoice.net.au/ who are brokers for solar power installers – probably one of many. I entered my location details and what size of system I was looking for and I quickly received quotes from a number of companies giving costs for different sized systems. The quotes were detailed giving warranties, brands and options.
I followed up on the quote of the company that had a competitive quote and that also offered good warranties. I rang them and given the size of our roof we would be able to use a 4kWh system. The quote for this system on this roof was $8105 (with an REC/ solar credit of $2765 – see clean energy council PDF) . I then tried to assess what a 4kW system would achieve.
It is hard to assess what our energy use will be, we know what it was but that was in an old house with electric heating. Trawling the web I get a figure of around 18kW/day as an average use for this size of house with this many people in it but we hope that it will be less because it is a better insulated building, with hydronic heating and LEDs throughout. A typical bill for a year, based on this assumption would be between $1200 and $2000. The saving we would expect to achieve with a 4kW system would be around $1200. This system would therefore cover most of our energy and would reduce the combined cost of our mortgage plus electricity. As a payback option (without using a loan with interest) the panels would take approximately 10yrs to payback assuming set-up costs are included – with a 30yr loan at 6% this increases to about 22years.
These figures are approximate because there are government incentives and changing rates at which you sell electricty – we sell back at a measly 8 cents per KW in Victoria currently. It is also hard to calculate because different power companies sell power at different prices at different times.
So to summarise it does seem to be a clear advantage to incorporate solar panels on our house.