The basic parameters associated with a typical solar panel installation for a residential application in 2018 included an average cost of $3,000 and an average installation size of 5 kW of power. According to a basic price demand curve in 2018 a typical installation of 300 units would cost approximately $15,000 per complete installation whereas $540 units would cost $12, 000 per complete installation.

What is the price elasticity of demand for a change in price from $15,000 to $13,500, and from $13,500 to $12,500 for a typical solar panel installation?