Solar Savings Calculator
How we calculated the savings
To keep things simple in the examples, we assume that an average household uses around 200 litres/day of 60°C hot water with an average annual cold water inlet temperature of 17.7°C. This average household with a fairly modern energy-efficient heater will consume around 4600 kWh per year of electricity for heating that amount of water.
We have assumed that a typical two-panel solar hot water installation will supply 75% of an average household's hot water needs from the sun. We believe this figure of 75% is realistic based on various systems' performance under federal government approved TRNSYS modelling.
So after going solar, this average household would save 3450 kWh per year of electricity. That's 75% of 4600 kWh.
Our base price for electricity in Year 1 is set at $0.16 per kWh. We have escalated this price over the 10 year comparison period at a rate of 6% per annum, which is conservatively in line with various government and industry forecasts.
If Australia moves to an emissions trading regime to combat global warming, then there may be a fairly steep jump in retail power prices well above the forecasts used in the above example. If that happens, your solar savings will increase in value.
The pricing of our quarterly lease payments will depend on movements in interest rates, just like your variable rate home mortgage. We have based our 7 year lease payments on an effective interest rate of 7.25%. If interest rates go up, you will pay a bit more, but this should be offset because you will most likely be paying more for electricity due to the increase in power prices. If interest rates go down you will pay less, but power prices probably won't go down.
We believe our forecasts of $0.16/kWh as a starting price for electricity, followed by a 6% annual increase and 7.25% for interest rates over the 7 year lease term are conservative. These conservative assumptions tend to underestimate the advantages of going solar.
Changing the assumptions
Our comparisons are based on Year 1 electricity price of $0.16/kWh with a 6% annual price increase thereafter and an average annual interest rate of 7.25%. You can change any of these assumptions to see how they affect the overall saving and the look of the Graph.
Anything we do now is based on our best estimate as to what might happen in the future. So why not satisfy yourself, by testing different assumptions to see just how valuable the Sunglow offer is.
To change any of the assumptions, just input the number you want, then click the CALCULATE button. You will then see how the Total Savings (i.e. total energy savings minus total lease payments) will change and how the Graph will change shape to show how your Lease Payments or Electricity Payments change over time.
Our comparisons are based on Year 1 electricity price of $0.16/kWh with a 6% annual price increase thereafter and an average annual interest rate of 7.25%. You can change any of these assumptions to see how they affect the overall saving and the look of the Graph.
Anything we do now is based on our best estimate as to what might happen in the future. So why not satisfy yourself, by testing different assumptions to see just how valuable the Sunglow offer is.
To change any of the assumptions, just input the number you want, then click the CALCULATE button. You will then see how the Total Savings (i.e. total energy savings minus total lease payments) will change and how the Graph will change shape to show how your Lease Payments or Electricity Payments change over time.
