I bought an additional Efergy E2 Wireless Electricity Monitor recently, after the end of the 60 cent feed-in-tariff in NSW and the change from "gross metering" to "nett metering" for solar production. I bought this one to monitor my instantaneous Solar Production (from my solar panels) from inside my home, since I already had one to monitor my instantaneous electricity use from the grid, also from inside my home. This first Efergy had performed well during the 6 years that I have had it. With these two monitors in place inside my home (with terrific phone advice from Efergy's technical people), I can now decide to use electrical appliances when my solar production is at a maximum, to reduce how much of my solar electricity production goes to the grid. The electricity company pays me 6 cents per kilowatt hour for the solar energy I produce, but charges customers (including me!) over 45 cents per kilowatt hour (in peak week-day afternoon times) i.e. they make over 700% profit. Now, the tech nerds will tell you that these monitors are not absolutely accurate but, for me, the numbers are accurate enough for me to easily adjust my appliance use to maximise the benefit I get from my solar panels and limit the solar energy I give away to the electricity company/grid. It's a terrific little product.