The analysis of energy bills shows that the common area energy usage is 402kWh per annum, with a cost of $458 p.a. This is mainly due to the eight external garden lights which operate on a timer. Given the energy usage for the common areas is extremely low, the study focuses on the feasibility of solar for offsetting individual townhouse electricity consumption.
With the assistance of strata committee members, energy bills for 11 of the 18 townhouses (anonymised) have been collected. The analysis shows the average daily energy usage for the sample of townhouses to be 10.8 kWh, with a weighted average usage rate of 26.99c/kWh including any discounts,and excluding fixed charges (eg daily supply charges). With the addition of fixed charges the average energy cost is 35.25c/kWh. Residents continue to face an increase in energy costs and several bills show a 26% increase in energy rates since July 2017.
In considering any solar energy system it is important to consider the energy usage profile across the hours of the day and seasons of the year. Solar energy systems should be sized based on the day time energy consumption of residents, which is mainly for fridges, air-conditioning and other household appliances.
The electricity prices have more than doubled in Australia over the past 10 years. Since July 2017, Australian households have been paying the highest energy prices in the world, which is two to three times more than American households. In the financial analysis, Wattblock assumes the electricity price will continue to increase at 3% per annum. This is conservative gives recent increases.