Works very well. Efficient enough to work in winter – I've had my Envirosun thermo-siphon with E25 panels through a Sydney winter and am able to run our household of 4 off 100% solar for many, maybe most days. Way more productive/ efficient than my previous solarhart L. The E25 panels are I think about 20% bigger, but the quality of the tank insulation and installation (pipes, valves etc) insulation probably also helps. My electricity consumption is down consistently throughout the year, on many winter days down by 40%/ 10kWh consistently (excluding overcast days). To be fair the SolarHart's performance had no doubt deteriorated with age (about 15 years old). But the difference is huge. It's a big call, expensive kit, but it looks like the extra cost will payoff within about 4-5 winters